Volume 21, Issue 1

The rheological properties of PAN/DMSO solution and the size and distribution of PAN coils were studied by rheology and dynamic light scattering (DLS) measurements. It was found that water could be used as a gel accelerator and increase the gel transition temperature T gel and the storage modulus G ′ as well as decrease the damping factor tan  δ through rheological measurements. DLS test shows that the average size of PAN coils increases significantly with the increase in gel accelerator content. In addition, the gel accelerator can change the mobility of PAN chains during the cooling process. The results show that the gel accelerator can enhance the entanglement of PAN macromolecular chains and improve the formation of three-dimensional network gel structure, so that PAN solution is more prone to gel transition during the cooling process.

Gellan is an anionic bacterial polysaccharide, which in aqueous solution dissociates into a charged gellan polymer molecule containing carboxyl ions and counter ions and forms thermoreversible gel under appropriate conditions. In this study, we investigated the effect of polymer concentration, the concentration of added monovalent metallic ion, and temperature on the DC electrical conductivity of the gellan. Results suggest that the DC conductivity decreases with the increasing polymer concentrations and the added monovalent metallic ions. Such a decrease in DC conductivity can be attributed to the reduction of the mobility of counter ions due to the increase in the crosslinking density of the gellan network. DC conductivity of gellan gels was increased with temperature, which is interpreted as the dissolution of physically cross-linked networks, thus increasing the mobility of counter ions. The behavior of temperature variation of DC electrical conductivity reveals an abrupt change at a specific temperature, which can be considered a way to determine the gel point or sol–gel transition temperature T c of this thermoreversible biopolymer gel. This result agrees with that of rheological measurements where the viscosity showed a similar trend with temperature and diverges to infinity at the temperature close to T c .

Polylactic acid (PLA) is one of the main components of biodegradable and biocompatible composites. Bacterial cellulose from kombucha membranes is an excellent candidate to be used as a natural filler of eco-composites because it is renewable, has low cost, low density, and acceptable specific strength properties, and is biodegradable. The study aimed to prepare composites of PLA and bacterial cellulose to produce a biodegradable and compostable material. The bacterial microcellulose was obtained from kombucha membranes and blended with PLA by extrusion. The composites contained a PLA with 1%, 3%, and 5% of cellulose. We characterized the PLA, bacterial microcellulose, and composites to ascertain their size and aspect, degree of crystallinity, distribution of the cellulose into PLA, and their mechanical properties. We observed an increase in crystallinity proportional to the cellulose content for the blends and found that the 3% cellulose blend withstands the stress of up to 40 MPa and temperatures up to 120°C before distortion.

Solvent-free and highly branched water-soluble polyester (WPET) is prepared through self-emulsification methodology, using dimethyl terephthalate (DMT), sodium dimethyl isophthalate-5-sulfonate (SIPM), trimethylolpropane (TMP), and ethylene glycol (EG) by the transesterification and polycondensation. The WPET were first utilized as surface-sizing agents for cellulose fiber paper. The structure, average molecular weights, and physical properties of the water-soluble polyester were characterized by FTIR, 1 H NMR, gel permeation chromatography (GPC), dynamic light scattering (DLS), X-ray diffraction (XRD), and dynamic rheometer. The effects of polymer structure and properties, as well as the surface sizing of the paper, were investigated. WPET displayed better surface sizing properties when it was prepared under the following conditions: –COO/–OH molar ratio of 1:2, the SIPM content of 17.98%, and TMP content of 11.10%. The relationships between the WPET structure and sized paper were clearly illustrated. The mechanical properties and water resistance of sized paper did not only depend on multi-branched hydroxyl groups of the WPET chains but also relied on the interactions among polymers and fibers, as well as the high toughness of surface sizing agent. The sizing paper possesses excellent mechanical properties as well as water resistance.

In this study, a poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) modified with nano-montmorillonite biocomposite (MMT/PHBH) was fabricated by solution-casting method. The results showed that the addition of MMT increased the crystallinity and the number of spherulites, which indicated that MMT was an effective nucleating agent for PHBH. The maximum decomposition peak of the biocomposites moved to a high temperature and residue presented an increasing trend. The biocomposites showed the best thermal stability at 1 wt% MMT. Compared with PHBH, 182.5% and 111.2% improvement in elastic modulus and tensile strength were obtained, respectively. Moreover, the oxygen permeability coefficient and the water vapor permeability of MMT/PHBH biocomposites decreased by 43.9% and 6.9%, respectively. It was also found that the simultaneous enhancements on the crystallizing, thermal stability, mechanical, and barrier properties of biocomposites were mainly caused by the formation of intercalated structure between PHBH and MMT.

An N- halamine precursor, namely, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-one (AHM), was used as a chain extender in the preparation of a series of N- halamine polyurethane (PU) films, in order to also instill antibacterial properties. The mechanical properties, thermodynamic performance, and antimicrobial performance of the functionalized PU films were systematically studied. The results showed that the addition of AHM could improve the thermodynamic and mechanical properties of the developed PU films. Conducting tests in the presence of Escherichia coli and Staphylococcus aureus as the model microorganisms revealed that prior to chlorination the antibacterial properties of the chlorinated PU-AHM-Cl films improved significantly relative to the analogous films. The excellent antibacterial properties and the overall superior performance of the PU-AHM-Cl films allow their potential application in microbiological protection materials and related fields. Graphical abstract The synthesis and activity of a series of polyurethane (PU) films functionalized with an antibacterial N- halamine precursor (AHM) are reported. The PU-AHM films exhibit excellent thermodynamic and mechanical properties. The chlorinated variants demonstrate superior storage, stability, and antibacterial effects.

Gastroretentive bilayer tablets of calcium carbonate (CC) were developed using D-optimal mixture design. The effect of formulation factors such as levels of HPMC K100 M (X1), sodium bicarbonate (X2), and HPMC E15 LV (X3) on responses like floating lag time (R1) and release of CC at 1 h (R2) and 6 h (R3) was elucidated. The optimized formulations developed by numerical optimization technique were found to have short floating lag time (2.85 ± 0.98 min), minimum burst release (27.02 ± 1.18%), and controlled yet near complete release (88.98 ± 2.75%) at 6 h. In vivo radiographic studies in rabbits indicated that optimized batch displayed a mean gastric retention time (GRT) of 5.5 ± 1 h which was significantly prolonged ( P < 0.05) compared to the conventional tablets that displayed a GRT of less than 1 h. The studies proved that the gastroretentive tablets can be a promising platform to improve bioavailability of nutrients having absorption window in upper gastrointestinal tract.

Sustainable nanocomposites with transparent, biodegradable, and enhanced mechanical and barrier properties were prepared by the incorporation of SiO 2 into poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBH) films and subsequent solvent casting. The crystallinity of composites could be increased by 67% with appropriate contents of SiO 2 , which proved that SiO 2 were effective nucleating agents for PHBH. And it was worth mentioning that the contributions of SiO 2 to the crystallization and thermal stability of composites are proved effectively by Avrami relationship and Horowitz and Metzger method. More importantly, compared with PHBH, it had not only an enhancement about 40% and 60% on the tensile strength and elastic modulus, respectively, but also half the reduction of the moisture and oxygen permeability which were much higher than the values of conventional plastics. The above, in conjunction with the low migration rate measured in food substitutes, illustrated unambiguously that the nanocomposites might be suitable for potential application in food packaging. Graphical abstract SiO 2 /PHBH nanocomposites with fine crystallization and improved mechanical and barrier properties.

The indiscriminate use of films as synthetic primary packaging, for the conservation and transport of fruit and vegetable products in postharvest, causes disposal problems. In the present work, films based on sodium alginate were synthesized and characterized, with alginate as a biopolymer matrix, glycerol (plasticizer), oleic acid (control of hydrophilicity), and calcium chloride (cross-linking agent). The dynamic mechanical, thermal, structural, and hydrophobicity properties were studied. In the case of dynamic mechanical properties, they were analyzed at a temperature of −50°C, because food packaging goes through storage during its cold chain, showing biofilm stability under these conditions. On the other hand, infrared spectroscopy analysis showed that the carboxylate and carboxy functional groups serve as a link for all the components, and oleic acid is also serving as a plasticizer and, to a lesser degree, as a hydrophilicity controller.

In spite of the high electrical conductivity of carbon nanotube (CNT), its tendency to aggregate and expensive cost in fabricating aerogel, foams, and porous materials remains a problem. Therefore, we described a simple and feasible way to design light-weight, high electrically conductive, and cost-efficient polylactic acid (PLA)/CNT foams. The branched PLA (BPLA) resin with excellent melt elasticity and foamability was induced by nucleophilic ring-opening reaction of epoxy-based acrylic/styrene copolymer and PLA. After that, BPLA/CNT composites and foams were prepared by melt-mixing and supercritical carbon dioxide foaming technology, respectively. The thermal, electrical, and foaming properties were studied. The resultant BPLA/CNT foam possessed a low density of 0.174 g/cm 3 and high crystallinity of 3.03%. An improvement of the oriented structure of CNT induced by cell growth in BPLA matrix increased the conductivity of the foam up to 3.51 × 10 4  Ω/m. The proposed foaming materials provided a way for designing and preparing high performance CNT products.

The term “structuring” used in silicone rubber describes a phenomenon of the increase in the viscosity of polydimethylsiloxane filled with silica during storage, which limits the applications of the room temperature vulcanized (RTV) silicone rubber in the field of aerospace and military. In this pursuit, the present study was envisaged to solve the problem of structuring of the RTV. A solvent-free method was used to hydrophobize the hydrophilic silica with hexamethyldisilazane. An RTV composition prepared using eight parts of hydrophobic silica with 2.91% C content exhibited a viscosity of less than 100 Pa s, with no significant change in 21 days. In contrast, eight parts of the hydrophilic fumed silica showed an initial viscosity of RTV to be greater than 2,000 Pa s. Silica samples with different adsorbed water content were used to prepare the RTV compositions. It was found that the viscosity of the RTV prepared using the sufficiently dried silica was 5.6 times lower than that of the wet silica. The “dissolution” model of the silica–silica hydrogen bonds in water was proposed. Furthermore, the change in the viscosity of the RTV compositions at different temperatures in the range of −15°C to 30°C was studied. The viscosity of RTV stored at –15°C for 34 days did not change significantly, whereas that stored at room temperature increased from 100 to 1,710 Pa s within 21 days.

Metallic nanoparticles are widely used due to their superior electrical, antimicrobial, and electromagnetic shielding characteristics. In this work, the surface functionalization of polypropylene (PP) fibers using magnetron sputtering with pure Cu and Ag targets in the presence of Ar gas was systematically investigated, in detail, in terms of surface morphology, tensile, abrasion resistance, moisture regain, antibacterial, and electrostatic properties. The results indicated that the nanocomposite films deposited on the PP surface were even and dense under proper treatment conditions. Compared with pristine fiber, breaking tenacity, abrasion resistance, and antibacterial properties of the Cu/Ag-deposited PP fibers were significantly improved, whereas the extension at break and moisture regain decreased in different degrees. Also, the electrostatic property of treated PP fabrics was studied. This work reveals that surface functionalization of Cu/Ag-deposited PP fiber is versatile, and the surface treatment that uses metallic nanoparticles by magnetron sputtering is a promising approach for achieving multifunctional textiles. Graphical abstract The Cu/Ag nanostructured film that follows Volmer–Weber growth pattern was successfully deposited onto PP fiber surface using the magnetron sputtering technique.

By introducing functional fillers into the ethylene propylene diene monomer matrix, the anti-ablation, thermal insulation, and adhesive layer were prepared, respectively. We have studied the mechanical properties, ablation properties, thermal insulation properties, and bonding properties of different composite structures after design and analyzed the ceramic mechanism. The results showed that the content of ceramic fillers improved the thermal stability and ablation properties of anti-ablation layer composites. The formation of liquid structure can fill the hole defects and ablation pit. The foaming agent improved thermal insulation properties of the thermal insulation layer, and the strength of the bonding layer has been greatly improved. The design of the composite structure can not only reduce the density but also have an excellent thermal insulation effect. And as the thickness of the heat insulation layer increases, the heat blocking effect becomes more excellent.

Nanomaterials have been treated as effective dopants for enhancing mechanical and ion-conductive properties of polymer membranes. Among various nanomaterials, metal–organic frameworks are attracting enormous attention from researchers because of their intriguing structural and functional properties. Here we report a gentle and simple synthesis method of ZIF-8 nanomaterials, which are applied as dopants for polyvinyl alcohol composite membranes. This nanomaterials display uniform size distribution and high purity through various structural investigations. The as-prepared polymer composite membranes present enhanced mechanical and ion-conductive properties compared to pristine samples. This work provides a novel ideal on the design of nanomaterial dopants for high-performance polymer membranes.

Carbon nanotubes (CNTs) were non-covalently modified by two categories of ionic liquids (ILs), including 1-vinyl-3-ethylimidazole bromide (VEIMBr) and 1-vinyl-3-hexylimidazole bromide (VHIMBr) in the ratio of 1:1 and 1:4, respectively. The surface interaction between CNTs and ILs was well-characterized by FTIR, Raman spectra, XPS, etc. Thermoplastic polyurethane (TPU) containing different amounts of CNTs/ILs was fabricated by melting blending method. TPU-CNTs/ILs composites exhibited simultaneously enhanced electromechanical properties with improved dielectric constant and lowered elastic modulus. The electromechanical sensitivity of sample TPU-3CNT/12VHIMBr increased by approximately 45 times in comparison with that of pure TPU at 200 Hz. Besides, improved dispersion of CNTs/ILs in the TPU matrix was also exhibited. Graphical abstract The cationic-π/π–π interaction existing between the surface of CNTs and the imidazole ring of ILs benefited the dispersion of CNTs in the TPU.

Low strength has always been one of the main factors limiting the application of foams. We acquire a natural rubber latex/MXene foam composite with high strength and versatility by adding MXene to the natural rubber latex. It is shown that natural rubber latex foam (NRF) with 2 and 3 phr of MXene shows obviously enhanced tensile strength by 171% and 157% separately as compared to that of neat NRF. Furthermore, the composite also has better electrical conductivity and electromagnetic shielding than NRF, which can be used in the automotive industry, aviation industry, and many other aspects.

With high polymer added into suspension, the use of abrasive slurry jet (ASJ) has significant advantages in energy management. The quality and efficiency of ASJ are affected distinctly by its structure and the flow field feature, both of which depend on the rheological properties of the abrasive slurry. Therefore, this paper carries out a series of experiments to study the rheological properties of abrasive slurry with polyacrylamide (PAM) and carboxy methyl cellulose (CMC) commonly used in ASJ. The paper also explores the effect of temperature and abrasive on the apparent viscosity of the abrasive slurry. Experimental results show that PAM and CMC solutions behave as a pseudoplastic non-Newtonian fluid in the selected concentration range, whose apparent viscosity increases with the concentration. In addition, specific non-Newtonian fluid constitutive equations of the power-law model for PAM and CMC solution were obtained by nonlinear fitting calculation. The apparent viscosity decreases with the growth of temperature because it leads to the increase in spacing between molecules, making the attraction between molecules smaller and smaller. However, the abrasive has no influence on the apparent viscosity of abrasive slurry for these molecular bonds, and their mechanical entanglements are not destroyed by abrasive particles in the suspension. Graphical abstract The results and conclusion of this paper can be used to study the formulation optimization and fluid field properties of abrasive slurry jet (ASJ), which also can provide guidance for the engineering application of ASJ.

A two-step polyaniline (PANI) loading procedure has been developed to produce polyelectrolyte complex composite membranes (CPECs) to be used as supercapacitor electrodes. In the first step, CPECs were prepared by co-precipitation of poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) mixed with various amounts of PANI as a filler. CPECs were formed by compression molding into 100 micron membranes using NaCl as a plasticizer and characterized for their electrochemical properties. In the second step, the highest capacitance CPEC membranes with 60% PANI loading were further modified and doped by crossflow polymerization of aniline through the composite membranes. By using a two-compartment crossflow reactor containing aniline and ammonium persulfate on each side, the PANI content of the composite membrane was further increased. Cyclic voltammetry showed a doubling in the capacitance of the membranes after the crossflow polymerization. The resulting electrodes were flexible with high capacitance and could be used to improve pseudocapacitor performance.

A fast, simple, and energy-saving microwave-assisted approach was successfully developed to prepare carbon microspheres. The carbon microspheres with a uniform particle size and good dispersity were prepared using glucose as the raw material and HCl as the dehydrating agent at low temperature (90°C) in an open system with the assistance of microwave heating. The carbon microspheres were characterized by elemental analysis, XRD, SEM, FTIR, TG, and Raman. The results showed that the carbon microspheres prepared under the condition of 18.5% (v/v) HCl and heating for 30 min by microwave had a narrow size distribution. The core–shell structure of the carbon core and TiO 2 shell was prepared with (NH 4 ) 2 TiF 6 , H 3 BO 3 using the microwave-assisted method. The hollow TiO 2 microspheres with good crystallinity and high photocatalytic properties were successfully prepared by sacrificing the carbon microspheres.

Dental implant treatment requires an available bone volume in the implantation site to ensure the implant’s mechanical stability. When the bone volume is insufficient, one must resort to surgical means such as guided bone regeneration (GBR). In GBR surgery, bone grafts and membranes are used. The objective of this work is to manufacture and characterize the in vitro and in vivo properties of resorbable collagen type I membranes (Green Membrane ® ) for GBR. Membrane surface morphology was characterized by SEM and roughness was measured using an interferometric noncontact 3D system. In vivo skin sensitization and toxicity tests have been performed on Wistar rats. Bone defects were prepared in 24 adult male rats, filled with biomaterials (Blue Bone ® and Bio Oss ® ) and covered with collagen membranes to maintain the mechanical stability of the site for bone regeneration. The incisions were closed with simple stitches; and 60 days after the surgery, the animals were euthanized. Results showed that the analyzed membrane was homogeneous, with collagen fiber webs and open pores. It had no sign of cytotoxicity and the cells at the insertion site showed no bone morphological changes. There was no tissue reaction and no statistical difference between Blue Bone ® and Bio Oss ® groups. The proposed membrane has no cytotoxicity and displays a biocompatibility profile that makes it suitable for GBR.

Processing capacity and product yield of three-dimensional (3D) smart responsive carriers are markedly superior to those of two-dimensional substrates with the same compositions due to the special structure; therefore, more attempts have been made to develop the 3D intelligent systems in recent decades. A novel preparation strategy of thermoresponsive glass sphere-based composite carriers was reported in this study. First, PNIPAAm copolymers were synthesized by free-radical polymerization of N -isopropylacrylamide (NIPAAm), hydroxypropyl methacrylate (HPM), and 3-trimethoxysilypropyl methacrylate (TMSPM). Then, the copolymer solution was sprayed on the surfaces of glass spheres using a self-made bottom-spray fluidized bed reactor, and the bonding between copolymers and glass spheres was fabricated by thermal annealing to form PNIPAAm copolymer/glass sphere composite carriers. The coating effects of PNIPAAm copolymers on sphere surfaces were investigated, including characteristic functional groups, surface microstructure, grafting density, equilibrium swelling, as well as biocompatibility and potential application for cell culture. The results show that the temperature-responsive PNIPAAm copolymers can be linked to the surfaces of glass spheres by bottom-spray coating technology, and the copolymer layers can be formed on the sphere surfaces. The composite carriers have excellent thermosensitivity and favorable biocompatibility, and they are available for effective cell adhesion and spontaneous cell detachment by the use of smart responsiveness. Graphical abstract Preparation of thermoresponsive glass sphere-based composite carriers via bottom-spray coating technology.

Biodegradable nanocomposites were prepared by melt blending biodegradable poly(lactic acid) (PLA) and poly(butylene adipate- co -butylene terephthalate) (PBAT) (70/30, w/w) with diatomite or talc (1–7%). From the SEM test, the particles were transported to the interface of two phases, which acted as an interface modifier to strengthen the interfacial adhesion between PLA and PBAT. Talc and diatomite acted as nucleating agents to improve the crystallization of PBAT in the blends by DSC analysis. Moreover, adding the particles improved the tensile and impact toughness of the blends. The elongation at break with 5% talc was 78% (vs ∼21%) and the impact strength was 15 kJ/m 2 (vs ∼6.5 kJ/m 2 ). The rheological measurement revealed that the talc and diatomite reduced the viscosity of the blends. The results showed a good possibility of using talc- and diatomite-filled PLA/PBAT blends with high toughness for green-packaging and bio-membranes application.

To curtail flammability risks and improve material properties, flame retardants (FRs) and fillers are mixed into rubbers. High loadings of aluminum trihydroxide (ATH) and carbon black (CB) are the most used FRs and reinforcing additive, respectively, in rubbers. To reduce loading without losing mechanical properties, partial substitution of ATH as well as CB by low amounts of multilayer graphene (MLG) nanoparticles is investigated. The high aspect ratio MLG is made of ten graphene sheets. In polybutadiene/chloroprene (BR/CR) nanocomposites 3 phr MLG replaced 15 phr CB and/or 3 phr ATH. Material and mechanical properties as well as fire behavior of the nanocomposites are compared to BR/CR with 20 phr CB both with and without 50 phr ATH. MLG appears as a promising nanofiller to improve the functional properties: replacement of CB improved rheological, curing, and mechanical properties; substitution of ATH improved nanocomposite properties without affecting flame retardancy.

The strain-dependent vertical and horizontal wicking of as-prepared cotton/lycra elastic woven fabric was systematically studied. The experimental results revealed that the fabric exhibited a strain strengthening effect. A higher tensile strain results in a higher equilibrium wicking height, and vice versa . Moreover, the results indicated that the proposed Laughlin–Davies model is capable of tracking well the experimental data and replicating the wicking characteristics of fabric under different levels of stretch. In addition, the wetting time and wicking area of fabric under different strains and height regimes were examined during horizontal wicking. It was found that the wetting time decreased with an increase of strain and/or water drop height. The strain-enhanced and height-weakened effects of wicking area were revealed. The spreading mechanism of water drop in elastic fabric was also proposed. Such fundamental work provides a basic support for the in-depth investigation of wicking behavior of complex stretchable textile structures.

In this work, strontium titanate (STO) was coated on the surface of carbon nanotubes (MWCNTs) through a sol–gel method to form a core–shell structure hybrid powder (STO@MWCNTs). This powder was then added to polydimethylsiloxane to prepare a flexible high-K composite. As coating, STO effectively prevents the overlap and agglomeration of MWCNTs, thereby passivating the percolation threshold of the composite. STO increases the dielectric properties of the composite as a high dielectric ceramic. Under a low filler loading amount of 11 wt%, the dielectric constant and dielectric loss of the composite are 53 and 0.1, respectively. In addition, the composite can still maintain superior breakdown strength and mechanical properties, given the relatively low filler concentration. The enhanced dielectric properties, breakdown strength, and tensile strength make the composite suitable for application as dielectric material in flexible and stretchable energy storage equipment.

Silica and carbon black (CB) co-filled rubber composite was widely used for tire tread and other rubber products because of combined advantages of binary fillers, such as low hysteresis, good abrasion resistance, and reinforcement. Numerous studies have been focused on the filler–rubber interaction with the aim of obtaining optimum performances. To investigate the effect of modification on properties of rubber composite, modified silica and CB co-filled rubber composite was prepared with a multi-functional silane coupling agent, 2-aminoethyl-2-(3-triethoxysilylpropyl)aminoethyl disulfide (ATD). Such modification significantly enhanced the filler–rubber interaction and improved the filler dispersion. For the modified composites, the state of cure, hardness, tensile strength before and after aging, stress at 300% elongation, tear strength, abrasion resistance, rebound resilience, compression set, temperature rise, and the value of dynamic loss coefficient ranging from −20°C to 80°C were significantly improved, especially with low ATD dosage (3.0 phr). This modification provides an effective route to prepare silica and CB co-filled rubber composites with improved mechanical properties and dynamic mechanical properties. Graphical abstract Silica and carbon black co-filled rubber composite was modified by multi-functional silane coupling agent. Such modification significantly enhanced the filler–rubber interaction and improved mechanical properties and dynamic mechanical properties.

An azido-terminated polyhedral oligomeric silsesquioxane (POSS) compound, octakis(azidopropyl-3-oxycarbonyl-1-decyl-10-thiopropyl-3-)POSS (OADTP), is synthesized and characterized. POSS-polytriazole (PTA) resins are prepared from an azide, an alkyne monomer, and OADTP. The toughening effect of OADTP on PTA resins is analyzed by impact performance test and electronic microscope characterization, and the thermal performance of resins is measured by thermogravimetric analysis and dynamic mechanical analysis. The results show that the addition of the POSS can improve the mechanical properties of PTA resins. The impact strength of POSS-PTA resins first increases and then decreases with the increase in the POSS compound, and the maximum one arrives at 54.8 kJ m −2 which increases by 44.2% as compared to 38 kJ m −2 of the PTA resin. A good thermal stability remains in POSS-PTA resins.

In this work, a phosphorous-containing flame retardant, phenylphosphonate-based compound (EHPP), is synthesized by alcoholysis and hydrazinolysis of phenylphosphonic dichloride, which is subsequently introduced to ethylene-vinyl-acetate (EVA) copolymer to improve its flame retardant performance. The resultant compound was characterized by Fourier transform infrared (FTIR), 1 H NMR, 13 C NMR, and 31 P NMR. The influence of the EHPP on the combustion behaviors of EVA is studied by limiting oxygen index (LOI), UL-94, and cone calorimeter test. The results show that 1 wt% EHPP can reduce peak heat release rate (PHRR) by 40%. Moreover, 2 wt% EHPP can increase LOI from 20.5% to 25.5%. Thermogravimetric analysis/infrared spectrometry (TGA-FTIR) was used to detect the gaseous products of EVA/EHPP to study the gaseous-phase flame retardant mechanism. The EHPP released phosphorus-containing radicals to capture highly active free radicals to improve the flame retardancy of EVA.

In this study, bentonite/epoxy sheet molding compound composites (BS/ESMC) were prepared with different bentonite contents (0.5, 1, 1.5, 2, 2.5, 5, and 10 wt%) by hot compression molding. The effects of BS content on the mechanical properties, thermal stability, and fire-retardant properties of samples were investigated. When the BS addition amount is 1.5%, the tensile strength, flexural strength, and impact strength reach the maximum, increasing by 24.15%, 26.56%, and 51.33%, respectively. The measurement of mechanical properties showed that the fracture toughness of BS/ESMC composite has been greatly improved from 71.41 to 108.07 MPa. As the content of the bentonite increases, the heat resistance of the sample increases, and the residual carbon content of the system increases by 61.54% when the amount of the bentonite added is 10%. In addition, the value of LOI increased from 25.6 to 27.9 with the addition of the bentonite.

In this work, octamercapto polyhedral oligomeric silsesquioxane (POSS-8SH) and octaphenol polyhedral oligomeric silsesquioxane (POSS-8Phenol) were successfully synthetized. POSS-8Phenol was added into the synthesis process of liquid thermoset phenolic resin (PR) to obtain POSS-modified phenolic resin (POSS-PR). Chemical structures of POSS-8SH, POSS-8Phenol, and POSS-PR were confirmed by FTIR and 1 H-NMR. TG and DTG analysis under different atmosphere showed that char yield of POSS-PR at 1,000°C increased from 58.6% to 65.2% in N 2 , which in air increased from 2.3% to 26.9% at 700°C. The maximum pyrolysis temperature in air increased from 543°C to 680°C, which meant better anti-oxidation properties. XRD results confirmed both POSS-8Phenol and POSS-PR-generated crystalline SiO 2 in air, which could explain the improvement of anti-oxidation properties. SEM showed that the POSS-PR had phase separation during curing process. Finally, carbon fiber fabric-reinforced POSS-PR (C-POSS-PR) was prepared to verify the anti-oxidation properties of POSS-PR.

To improve the level dyeing property and colorfastness of natural pigment-dyed cellulose fiber, a study on the structure and properties of natural indigo spun-dyed viscose fiber was carried out systematically. Herein, the natural pigment-dyed cellulose fiber was prepared by wet-spinning technique, and the microstructure of the colored fiber was comprehensively studied. Fabrics with different color depths were obtained by adjusting the color value and the content of indigo pigment. The natural indigo was evenly embedded in the viscose fiber, and the results indicated the existence of a direct ratio relationship between the performance of natural indigo and the color depth of the fiber. The level dyeing property and colorfastness of the fabric were tested. The fabric exhibited excellent dyeing uniformity, as indicated by the relative standard deviation of the surface color depth value on the fabric, which was no more than 2.39%. The colorfastness of natural indigo spun-dyed fiber was outstanding even when mordant was not used in the production process. The colorfastness to artificial light could reach grade 5, the fastness to washing with detergent reached grade 3–4, the fastness to rubbing reached grade 4–5, and that to high temperature reached grade 4–5. These results can possibly promote the future use of natural dyes in the fiber produced by a spun-dyeing technique. Graphical abstract The natural indigo was embedded evenly in the fiber by a wet-spinning process. The fabric showed good dyeing uniformity. Although no mordant was used, good colorfastness was acquired.

A series of novel biodegradable copolyesters named poly(butylene 3-methyl adipate co -terephthalate) (PBA m T) were synthesized from the monomers of 3-methyl adipic acid (AA m ), 1,4-butanediol (BDO), and terephthalic acid (TPA) through a process of esterification and polycondensation. 1 H NMR analysis shows that they are random copolymers whose composition can be well controlled by the feed ratio of monomers. From the results of DSC and XRD, the introduction of methyl group successfully destroys the crystallizability of the PBA m chains, thus making it become a relative soft segment compared to PBA, while these random PBA m T copolymers constructed by soft segment PBA m and rigid segment PBT change from semi-crystalline polymers to nearly amorphous polymers as the feed ratio of A m increases. Especially, mechanical tests reveal that the copolymers show outstanding elasticity and rebound resilience with excellent strength. These thermoplastic copolyester elastomers with good performance by simply introduction of branched methyl group on polybutylene adipate terephthalate (PBAT) copolymer chains may well explore the potential application of biodegradable PBAT-based material. Graphical abstract Methyl branched PBA m T possesses excellent elasticity and shows certain degradation performance.

The chapter deals with the performance evaluation of the polyethylene of raised temperature resistance (PE-RT) and polyethylene (PE) using autoclave test under sour oil and gas medium conditions. The analyses of performance changes showed that PE-RT has good media resistance at 60°C. As the temperature increases, its mechanical properties decrease, accompanied by an increase in weight. Comparative analyses showed that no matter what temperature conditions are, PE-RT media resistance is better than PE80. The better media resistance of PE-RT depends on its higher degree of branching. Short branches are distributed between the crystals to form a connection between the crystals, thereby improving its heat resistance and stress under high-temperature conditions. PE-RT forms an excellent three-dimensional network structure through copolymerization, ensuring that it has better media resistance than PE80. However, the mechanical performance will be attenuated due to the high service temperature.

Polydimethylsiloxane (PDMS) is widely used from biomedical to industrial applications due to its nontoxic, hydrophobic, and transparent characteristics. PDMS has good thermal and adhesion properties; however, its mechanical properties are comparatively weak. Therefore, PDMS is blended with various polymers to effectively improve its mechanical properties. In this study, polyurethane (PU)–polydimethylsiloxane (PDMS) blended coatings of different concentrations were applied on the AISI 316L stainless steel surface. Their effects on corrosion and tribocorrosion properties were investigated in Ringer’s solutions. The blended polymer coatings were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The thermal properties of samples were examined by TGA and DSC. The surface images and cross-sectional were investigated using scanning electron microscopy (SEM). Tribocorrosion tests were carried out at open circuit potential (OCP). It was determined that hydrophobicity and thermal stability of polymer coating increased, while corrosion resistance slightly decreased with the increasing PDMS concentration in the polymer blended. The friction coefficient of blends decreased as the PU concentration increased. As a result, it was determined that the polymer-coated samples containing up to 50% PDMS prevented corrosive wear under the OCP wear test in Ringer’s solutions.

As a potential physical blowing agent, sodium bicarbonate (SB) is environmentally friendly and low in cost, but its low decomposition temperature cannot meet the requirements of polyolefin foam materials. Herein, for enhancing the thermal properties of SB, a modified way was offered to fabricate various SB-based capsules via suspension polymerization. As the modified SB-based capsules, epoxy resin (EP) accompanied with several organic acids was successfully coated on the surface of SB, serving as heat-insulation layer of SB. Various physicochemical characterizations provided reliable evidences for the good coating effect, and the thermal performance of the modified SB was improved. Further, the composite SB capsules were applied for the foaming of polypropylene (PP), and the foaming behavior of the SB-based capsules in PP was significantly improved, with more uniform distribution, smaller cell diameter, and higher cell density. In all, this work fully proved that the coated shells enhanced the thermal properties of SB, and the modified SB capsules significantly improved the foaming quality of foamed PP.

The effect of the olive pomace flour (OPF) addition on the mechanical, water uptake, morphological, and thermal properties of polypropylene (PP) with and without the use of two coupling agents was investigated. A higher percentage of a coupling agent yielded a greater impact strength of 141 J/m. Tensile and flexural properties of the OPF/PP composite were improved with the two coupling agents. The addition of OPF to pure PP had reduced these properties, thus proving the utility of the coupling agents. While the addition of the OPF to PP increased the water uptake property by 1.36%, the subsequent addition of a coupling agent decreased it to 0.78%. For the neat PP, the enthalpy of melting (∆ H m = 123 J/g), the enthalpy of crystallization (∆ H c = 133 J/g), and the percent of crystallinity ( X c = 59%) values showed a declining trend down to 91, 103 J/g, and 44%, respectively, when the filler and coupling agents added to the composite. The results of this study demonstrated that the OPF could be used as a viable reinforcement for the PP, providing good mechanical and morphological properties, as long as an appropriate coupling agent proportion is added to the composite. Graphical abstract While a higher percentage of a coupling agent consistently yielded a greater impact, tensile and flexural strength, it reduced melting enthalpy, percent crystallinity, and water absorption for the OPF/PP composite.

Highly stretched and conductive hydrogels, especially synthetized from natural polymers, are beneficial for highly stretched electronic equipment which is applied in extreme environment. We designed and prepared robust and tough alginate hydrogels (GMA-SA-PAM) using the ingenious strategy of fully interpenetrating cross-linking, in which the glycidyl methacrylate (GMA) was used to modify sodium alginate (SA) and then copolymerized with acrylamide (AM) and methylenebisacrylamide (BIS) as cross-linkers. The complete cross-linked structures can averagely dissipate energy and the polymer structures can maintain hydrogels that are three-dimensional to greatly improve the mechanical performance of hydrogels. The GMA-SA-PAM hydrogels display ultra-stretchable (strain up to ∼407% of tensile strain) and highly compressible (∼57% of compression strain) properties. In addition, soaking the GMA-SA-PAM hydrogel in 5 wt% NaCl solution also endows the conductivity of the hydrogel (this hydrogel was named as GSP-Na) with excellent conductive properties (5.26 S m −1 ). The GSP-Na hydrogel with high stability, durability, as well as wide range extent sensor is also demonstrated by researching the electrochemical signals and showing the potential for applications in wearable and quickly responded electronics.

The polyacrylonitrile (PAN) nanofiber membrane prepared by the electrospinning technology was used as the matrix, and β-cyclodextrin (β-CD) was introduced into it to synthesize the composite nanofiber membrane. Taking methylene blue as the object, the adsorption performance of nanofiber membranes for dyes in the aqueous solution was studied. The structure, morphology, and specific surface area of the nanofiber membrane were characterized using FTIR, SEM, BET, XRD, and EDS. Meantime, the adsorption equilibrium was also explored. After being modified by cyclodextrin, a large number of cavity structures and hydrophobic binding sites were provided for the nanofiber membrane, and the adsorption performance was significantly improved. The results showed that the maximum adsorption capacity of the PAN/β-CD blend nanofiber membrane (at 25℃) for methylene blue was 108.66 mg g −1 . The effects of pH, adsorption time, ion concentration, and adsorbent dosage on the adsorption capacity were also investigated. In addition, by fitting with the adsorption model, the adsorption process was more complex with the quasi-secondary adsorption kinetics and Langmuir isotherm adsorption model. Graphical abstract Preparation and adsorption process of PAN/β-CD nanofiber membranes.

Cylindrical-electrode-assisted solution blowing spinning (CSBS) is a novel technique of fabricating nanofibers. In this paper, a combination of numerical simulation, theoretical analysis, and experiment is used to study the influences of CSBS airflow field and electric field on the fabrication of CSBS nanofibers for the first time. The effects of air pressure and injection speed on the morphology of CSBS fiber are studied. The research results show that the increase in air pressure will increase the centerline velocity and the centerline turbulence intensity within the effective stretching distance of the airflow. The increase in centerline velocity will result in a decrease in the diameter of CSBS fibers. There is a negative correlation between jet diameter and surface charge density of CSBS jet. The increase in air pressure will increase the stretching of the jet by the air flow, which will make the jet more likely to become thinner again because of the charge repulsion. Increasing air pressure will reduce the porosity of the nonwoven. As the injection speed increases, the diameter of CSBS fiber increases, and the porosity of the nonwoven decreases first and then increases. This work provides theoretical and experimental bases for the controllable preparation of CSBS nanofibers.

Nonrubber components (NRCs) play an important role in the outstanding mechanical property of natural rubber (NR). The main inositol component of NRCs in natural rubber latex (NRL) is l -quebrachitol. In this study, the influence of l -quebrachitol on the properties of centrifuged natural rubber (CNR) was investigated. The NRL was centrifuged twice to remove most of the NRCs. After that, l -quebrachitol was added in the latex with per hundreds of rubber (phr) vary from 0% to 0.8%, and the vulcanized CNR were prepared. It is shown that the properties of vulcanized CNR were greatly changed, with T 90 reduced from 19 to 15 min, the tensile strength increased from 5 to 9 MPa, T g reduced by about 2°C, and the ability for strain-induced crystallization was enhanced. It was proved by FTIR results that l -quebrachitol was linked to the CNR crosslinking network with ester bond.

A novel biodegradable protein-based material (UMSPIE) that consists of natural polymer soy protein isolate (SPI), ultrasonic-modified montmorillonite (UMMT), and ethylene glycol diglycidyl ether (EGDE) was produced by solution casting. Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) were used to characterize the chemical structure and micro-morphologies of as-synthesized protein-based composite films. The results showed that the interlayer structure of MMT was destroyed by ultrasonic treatment, and the hydrogen bonding between SPI chains and the ultrasound-treated MMT plates was enhanced. The synergistic effect of UMMT and EGDE on SPI molecules made the network structure of the UMSPIE film denser. In addition, the mechanical and barrier properties of the as-synthesized films were explored. Compared with pure soy protein film, the tensile strength of the UMSPIE film has an increase of 266.82% (increasing from 4.4 to 16.14 MPa). From the above, the modified strategy of layered silicates filling combining crosslinking agents is considered as an effective method to improve the functional properties of bio-based polymer composites.

In the continuous molding of microporous plastics, the polymer/CO 2 homogeneous body needs to be formed in a very short time, which affects the subsequent bubble nucleation, bubble pore distribution, and growth, and is the key to the molding. It is known that the formation time of homogeneous body is shortened during the continuous molding of microporous plastics because of the agitator’s effect. However, different agitators have different effects on the dissolution rate. So, it is necessary to study not only the dissolution of gas in polymer melt under static condition but also the dissolution under the action of the agitator. In this article, the solubility and dissolution rate of supercritical CO 2 in polymer melt PS at different temperatures and pressures were experimentally investigated under conical and screw agitators, and the numerical solution was also carried out.

The thermal-reflective coating technology can effectively realize the active cooling of asphalt pavement, thus delaying the occurrence of pavement rutting. Although solid fillers are usually used to absorb light and weaken light dazzle in traditional thermal-reflective coatings, this method makes the filler component complicated and the coatings more viscous and increases the difficulty of painting the coating material on the pavement surface. On account of all the aforementioned factors, this experimental study aims to effectively improve the performance of the thermal-reflective coating with liquid silicone rubber addition in which epoxy resin is the base material and rutile titanium dioxide is the pigment filler for the coating film. Through lab experiments, the effects of the proper liquid silicone rubber dosage on the glossiness, cooling performance, and hardness of the thermal-reflective coating are studied and analyzed. The experimental results show that the liquid silicone is very effective for coating toughness improvement. The thermal-reflective coating, when the liquid silicone rubber dosage changes from 10 to 14 wt%, exhibits a matt state, and its glossiness can be controlled below 30 GU, which meets the safety and antiglare requirements of traffic vehicles. It demonstrates that liquid silicone rubber can influence the viscosity of the thermal-reflective coatings, and when the liquid silicone dosage reaches 16 wt%, the viscosity of the coating increases by 7.26 wt% less than that of the solid matting filler. Liquid silicone rubber can also influence the cooling effect of the thermal-reflective coatings, with the liquid silicone rubber dosage of 16 wt%, the asphalt pavement temperature can reduce 0.5°C. Besides, liquid silicone rubber reduces the hardness of the coatings, the coating hardness is 6H when the liquid silicone rubber dosage is 0–10 wt%, and the hardness of the coating reduces to 5H when liquid silicone dosage is from 12 to 16 wt%, which meets the actual requirements. Therefore, this article recommends a 12 wt% dosage of the liquid silicone rubber to be used as a matting filler for the thermal-reflective coatings.

Snus is one of the types of smokeless tobaccos, which is popular in many countries and regions. The nicotine level in the plasma samples obtained from snus users is similar to the nicotine level obtained from cigarette smokers; hence, the snus users find it difficult to quit. The aim of this study is to develop new semi-interpenetrating polymer (SIPN) membranes that control the stable release of nicotine from snus, achieving the purpose of quitting smoking. Here, the SIPN comprising a polyacrylate network and PEG chains was synthesized through in situ radical polymerization. The SIPN was characterized by Fourier transform infrared spectroscopy, contact angle, differential scanning calorimetry, scanning electron microscopy, cytotoxicity, and in vitro release experiments. Furthermore, this SIPN was used to evaluate the release properties of nicotine in different snus samples varying in moisture, pH, and the tobacco’s particle size. The results indicated that the new SIPN could control release of nicotine at a specific rate, and the release rate could be adjusted according to the customer requirements. Thus, the new SIPN was contributed to build a new nicotine replacement therapy that served the snus users.

Polymeric-based composites can contribute to enhancing the detection, stability, and performance of enzymatic biosensors, due to their high structural stability, conductivity, and biocompatibility. This work presents the fabrication of a nanocomposite of polyaniline (PAni)/gold nanoparticles (AuNP)/carboxylated multiwalled carbon nanotubes (cMWCNT) as functional support for covalently linked catalase (CAT) enzyme. PAni was electropolymerized on a screen-printed carbon electrode (SPCE) and decorated with AuNP to improve charge transfer properties. CAT was bonded through amide formation using the carboxylic groups of cMWCNT, resulting in PAni/AuNP/cMWCNT/CAT biosensor. The structural and electroactive characteristics of the nanocomposite were studied by SEM, FT-IR, and cyclic voltammetry. The optimal performance was achieved after CAT immobilization over PAni/AuNP/cMWCNT/nanocomposite, showing improved analytical features such as a fast amperometric response of 1.28 s, a wide detection range from 0.01 to 6.8 mM, a correlation coefficient ( R 2 ) of 0.9921, a low detection limit of 2.34 µM, and an average recovery rate of 99.6% when evaluated in milk samples. Additionally, the bioelectrode showed excellent selectivity and retained bioactivity after 30 days of storage. Such remarkable performance proved the synergistic effects of both the high surface area of the cMWCNT and AuNP and the inherent PAni electroactivity, yielding direct electron transfer from CAT.

In this article, five kinds of soybean oil-based polyols (polyol-E, polyol-P, polyol-I, polyol-B, and polyol-M) were prepared by ring-opening the epoxy groups in epoxidized soybean oil (ESO) with ethyl alcohol, 1-pentanol, isoamyl alcohol, p -tert-butylphenol, and 4-methoxyphenol in the presence of tetrafluoroboric acid as the catalyst. The SOPs were characterized by FTIR, 1 H NMR, GPC, viscosity, and hydroxyl numbers. Compared with ESO, the retention time of SOPs is shortened, indicating that the molecular weight of SOPs is increased. The structure of different monomers can significantly affect the hydroxyl numbers of SOPs. Due to the large steric hindrance of isoamyl alcohol, p -hydroxyanisole, and p -tert-butylphenol, SOPs prepared by these three monomers often undergo further dehydration to ether reactions, which consumes the hydroxyl of polyols, thus forming dimers and multimers; therefore, the hydroxyl numbers are much lower than polyol-E and polyol-P. The viscosity of polyol-E and polyol-P is much lower than that of polyol-I, polyol-B, and polyol-M. A longer distance between the molecules and the smaller intermolecular force makes the SOPs dehydrate to ether again. This generates dimer or polymers and makes the viscosity of these SOPs larger, and the molecular weight greatly increases.

An imprinted electrospun fiber membrane was developed for the detection of volatile organic acids, which are key components of human body odor. In this study, hexanoic acid (HA) was selected as the target, polymethyl methacrylate (PMMA) was used as the substrate, and colorimetric detection of HA was achieved by a bromocresol purple (BCP) chromogenic agent. The results showed that the morphology of the fiber membrane was uniform and continuous, and it showed excellent selectivity and specificity to HA. Photographs of the color changes before and after fiber membrane adsorption were recorded by a camera and quantified by ImageJ software by the difference in gray value (ΔGray). This method is simple, intuitive, and low cost and has great potential for application in human odor analysis.

Poly(propylene carbonate) (PPC) is an emerging low-cost biodegradable plastic with potential application in many fields. However, compared with polyolefin plastics, the major limitations of PPC are its poor mechanical and thermal properties. Herein, a thermoplastic PPC containing cross-linked networks, one-pot synthesized by the copolymerization of carbon dioxide, propylene oxide, and 4,4ʹ-(hexafluoroisopropylidene) diphthalic anhydride, had excellent thermal and mechanical properties and dimensional stability. The weight-average molecular weight and the polymer yield of the PPC5 were up to 212 kg mol −1 and 104 g polym  g cat −1 , respectively. The 5% thermal weight loss temperature reached 320°C, and it could withstand a tensile force of 52 MPa. This cross-linked PPC has excellent properties and is expected to be used under extreme conditions, as the material can withstand strong tension and will not deform.

The research on facile, low-cost, and green process for the uniform dispersion of graphene nanoplatelets (GNPs) into polymer matrix has always been a considerable challenge in practical applications. The Van der Waals interaction between graphene layers can easily cause aggregation of the nanofillers. Here, we propose a new method to solve this problem by involving solid-state shear mixing to obtain a well-dispersed nanocomposite. The comprehensive properties of nanocomposite, including antistatic properties, mechanical properties, and thermal stability, can be significantly enhanced by this method. The surface resistivity of the nanocomposite can be up to 2.4 × 10 7  Ω sq −1 under 1 wt% content of GNPs, which is significantly better than the value obtained by conventional melting compounding and meets the required standard of less than 3 × 10 8  Ω sq −1 for actual application antistatic materials. The impact strength of the nanocomposite increased by 120.8% when compared with neat PP. At the same time, the heat distortion temperature and initial decomposition temperature of the nanocomposite with only 0.5 wt% content of GNPs are improved by 11.7°C and 110°C, respectively. In addition, GNPs is a heterogeneous nucleating agent that leads PP to emerge β crystal form. This study provides an effective and practical reference for the broad-scale industrial preparation of polymer-based graphene nanocomposites. Graphical abstract Polypropylene/GNP nanocomposites with enhanced antistatic performance, impact strength, and thermostability via solid-state shear mixing processed.

Polymer fiber reinforcement can elevate the pavement performance indicators of asphalt concrete, including low temperature crack resistance, high temperature stability, and water stability. Fiber-reinforced asphalt concrete (FRAC) is a suitable solution to improve the road performance of asphalt concrete. However, the mechanism of the fiber parameters in asphalt concrete has still not been introduced. Herein we studied the influence of fiber geometry characteristics on improving the mechanical properties of asphalt concrete through numerical simulation. The finite element method (FEM) was used to establish an elastoplastic mesoscopic model for indirect tensile test of the asphalt mixtures via ABAQUS. The best fiber length, volume ratio, diameter, and modulus were confirmed based on the simulated results. Furthermore, the indirect tensile tests were undertaken to prove the influence of polyacrylonitrile (PAN) and polyvinyl alcohol (PVA) fiber parameters on the FRAC’s splitting stability. This study fills the gap between theoretical simulations and laboratory experiments, and it is a promising solution to improve engineered FRAC road performance. Graphical abstract The research objectives, modeling, and tensile test strategy of fiber-reinforced asphalt concrete.

Design of experiments is used to optimize ratios between deproteinized natural rubber latex, Eudragit ® NM 30 D, and pectin for nicotine buccal film with dependent variables as moisture content, moisture uptake, and swelling index in simulated saliva 3 and 5 h. Mathematical models were linear for moisture content and moisture uptake, while swelling index in simulated saliva 3 and 5 h was a quadratic model. Optimized polymer ratio was 0.319:0.362:0.319, respectively. Experimental values were 13.17 ± 0.92%, 3.96 ± 0.84%, 112.58 ± 22.63%, and 124.69 ± 8.01% for dependent variables, respectively. The buccal film showed high swelling at pH 7 and swelling–deswelling behaviors in a water/ethanol environment. The surface pH, weight, and thickness were 8.11, 63.28 ± 6.18 mg, and 219.87 ± 44.28 µm, respectively. Nicotine content was found as 10.22 ± 0.46 mg/4 cm 2 . Maximum cumulative nicotine release was 9.82 ± 0.94 mg/4 cm 2 . Kinetic model fitted to the Korsmeyer-Peppas model and release exponent was 0.36, representing that release mechanism was controlled by Fickian diffusion release.

The mangosteen peel extract (MPE) was used to obtain soy protein isolate (SPI) films. The results show that MPE exhibited a high content of total phenolics and antioxidant activity. Moreover, the MPE can enhance the antibacterial–antioxidant properties, UV-visible light barrier properties, and water-resistant properties of the SPI films. The presence of MPE resulted in an increase in water vapor permeability and hydrophobicity. The extract addition also reduced the film’s crystallinity along with a decrease in the mechanical property and lowering of the maximum degradation temperature. Attenuated total reflectance Fourier transform infrared spectroscopy revealed that the polyphenols in MPE could interact with SPI through hydrogen bonds and hydrophobic interactions, and the addition of MPE changed the secondary structure of SPI with a decrease in β-sheets and an increase in β-turns and random coils. Scanning electron microscopy showed that all the films exhibited smooth and homogenous morphology on the surface and on some layers through cross-sectional images. Our results suggested that the MPE would be a promising ingredient to make SPI films used as an active packaging material.

In this study, a novel functional monomer N -(1-(2,4-difluorophenyl)-2-(1 H -1,2,4-triazol-1-yl)ethyl)acrylamide (NDTEA) was designed and synthesized, and was used to prepare Ni( ii ) ion-imprinted polymers (Ni( ii )-IIPs). Sixteen kinds of Ni( ii )-IIP (Ni( ii )-IIP 1–16 ) and corresponding non-imprinted polymers (NIP 1–16 ) were prepared by precipitation polymerization method. After optimized condition experiment, Ni( ii )-IIP 5 possessed maximum adsorption capacity and better imprinting factor under optimal experimental conditions which indicated by equilibrium adsorption experiments. The morphology and structural characteristics of Ni( ii )-IIP 5 were characterized by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET). The adsorption selectivity of Ni( ii )-IIP 5 was analyzed by ICP-OES, and the results showed that Ni( ii )-IIP 5 had favorable selectivity recognition ability for Ni( ii ) when Cu( ii ), Co( ii ), and Cd( ii ) are used as competitive ions. The kinetic experiment indicated that the performance of Ni( ii ) adsorption on the surface of Ni( ii )-IIP 5 obeyed the pseudo-first-order model, and adsorption equilibrium was attained after 15 min. Isothermal adsorption process fitted to Langmuir and Freundlich isothermal adsorption models, simultaneously. The results showed that Ni( ii )-IIP 5 prepared by using a new functional monomer had better permeation selectivity and higher affinity for Ni( ii ), which also verified the rationality of the functional monomer design. At the same time, it also provided a broad application prospect for removal of Ni( ii ) in complex samples.

Cancer prevention and treatment are currently the focus of most research. Dose verification is an important step for reducing the improper dose deposition during radiotherapy. To mend the traditional gel dosimeters for 3D dose verification, a novel rare-earth nanoparticle-based composite gel was prepared, which has good radioluminescence property and reusability. It is a promising phantom material for the new 3D gel dosimeter. TEM, DLS, FT-IR, TGA, and spectrofluorometer were used to determine the chemical structure, micromorphology, and optical performance. Compared to the traditional gel dosimeters, the composite gel has a good linear relationship between the light intensity excited by X-ray and the tube current. Furthermore, it may measure the dose distribution immediately in situ , which reduces errors and saves time. This work provides a new idea for the research of 3D gel dosimeters and promotes the safe and effective use of radiotherapy.

Although natural fibre-based thermoplastic composites (NFCs) have the advantages of environmental compatibility and low cost, their mechanical properties are still relatively poor. Hybridization with basalt fibres (BFs) can broaden the industrial applications of NFCs. Hybrid composites were manufactured by means of interlayer hybrid reinforcement; that is, the hybrid composites were prepared by the lamination moulding of BF prepregs and hemp/polylactide fibre (HF/PLA) felts. The effects of cryogenic treatment and interfacial modification in BF hybridization on the mechanical properties of HF/PLA composites were investigated. The study revealed that the hybridization of BFs with hemp fibres (HFs) significantly increased the mechanical properties of composites, and the cryogenic treatment and interface modification of BFs also improved the performance of hybrid composites. Compared with those of untreated BF-reinforced composites (UBF/HF/PLA), the tensile strength, flexural strength, and impact strength were increased by approximately 28.5% (120.82 MPa), 44.6% (90.29 MPa), and 192.1% (61.0 kJ/m 2 ), respectively. Graphical abstract Preparation process of hybrid fibre-reinforced composites.

Super-hydrophobic fabrics have shown great potential during the last decade owing to their novel functions and enormous potential for diver’s applications. Surface textures and low surface energy coatings are the keys to high water repellency. However, the toxicity of nanomaterials, long perfluorinated side-chain polymers, and the fragile of micro/nano-texture lead to the super-hydrophobic surfaces are confined to small-scale uses. Thus, in this article, a stable polydimethylsiloxane (PDMS)-coated super-hydrophobic poly(ethylene terephthalate) (PET) fabric (PDMS- g -PET) is manufactured via dip-plasma crosslinking without changing the wearing comfort. Benefiting from the special wrinkled structure of PDMS film, the coating is durable enough against physical abrasion and repeated washing damage, which is suffered from 100 cycles of washing or 500 abrasion cycles, and the water contact angle is still above 150°. This study promotes the way for the development of environmentally friendly, safe, and cost-efficient for designing durable superhydrophobic coatings for various practical applications.

A series of natural rubber/butyl rubber NR/IIR blend loaded with N660 carbon black (CB) and triethoxy vinyl silane treated clay nanoparticles (TCNPs) were prepared using gamma irradiation in the presence of a polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). The effect of incorporating different contents of N660 CB and five parts per hundred of rubber (phr) of treated clay on the mechanical properties of the prepared nanocomposites has been investigated. The addition of TCNP to CB/rubber composites markedly increase their tensile strength due to the increase of the cross-link density. These results indicated that the TCNP may be enclosed or trapped in the occluded structure of CB. The effect of CB and the TCNP content on the tensile strength ( σ ), elongation at break ( ε b , %), and modulus of elasticity ( E , MPa) of natural rubber/butyl rubber NR/IIR blend have been investigated. The incorporation of 5 phr of TCNP into 30 phr CB-loaded NR/IIR composites results in the increased tensile strength value by about 60%. Finally, theoretical models were used to interpret the experimental results.

Natural silk fiber (SF) was introduced into the chitosan/nano-hydroxyapatite (CS/n-HA) system to fabricate a novel guided bone tissue regeneration (GBR) membrane. The effect of different treatment methods (degummed, un-degummed, or dissolved SF) and different contents of SF on the properties of the CS/n-HA composite membrane was investigated. Results demonstrated that the degummed SF/CS/n-HA composite membrane with a weight ratio of 2:6:2 possessed the highest mechanical strength, where SF supported the composite membrane as a skeleton frame in the form of primeval state, while the un-degummed SF and dissolved SF had weaker reinforce effect due to the poor interface or poor interaction between SF and CS, and the dissolved SF/CS/n-HA composite membrane displayed the fastest degradation. However, the three SF could all improve the cell biocompatibility of the CS/n-HA composite membrane. Conclusively, the study revealed that degummed SF could in situ reinforce the CS/n-HA composite membrane with a simple and green processing method, which would provide an important guidance significant to develop a novel GBR membrane.

To study the effect of doping hexagonal boron nitride (h-BN) on the thermal properties and insulation resistance of epoxy resin (EP) and the mechanism of this effect, h-BN/epoxy composites with h-BN content of 0, 10, 20, 30, and 40 phr were prepared. Meanwhile, the corresponding molecular dynamics model of h-BN/epoxy composites was established, and the thermal conductivity, volume resistivity, glass transition temperature, and microstructure parameters of h-BN/epoxy composites were obtained. When the h-BN content is 40 phr, the thermal conductivity of h-BN/epoxy composite is increased by 138% compared to pure EP, and the glass transition temperature is increased by 76 K. At the same time, doping h-BN will reduce the insulation performance of EP. However, the lowest volume resistivity of h-BN/epoxy composite is still 1.43 × 10 15  Ω·cm, and the EP composite still has good insulation performance. The fraction free volume and mean square displacement of EP decrease with the doping of h-BN, which indicates that h-BN can hinder the movement of molecular segments of EP, which is the reason for the increase in glass transition temperature.

After polymer flooding, a low-resistant dominant seepage channel forms at the bottom of the high-permeability reservoir, which is extremely disadvantageous for further enhanced oil recovery. In this study, we proposed a new method to plug the dominant seepage channel after polymer flooding, through fracturing–seepage–plugging using a solid-free plugging agent, which can achieve deeper and further regional plugging. This method involved dissolving the crosslinking agent and stabilizer in the water-based fracturing fluid (hereinafter referred to as the fracturing plugging agent) and transporting it to the target reservoir through hydraulic fractures. The fracturing plugging agent percolated into the deep part of the reservoir under the action of fracture closure pressure and gelled with the residual polymer in the formation to achieve deep regional plugging of the advantageous channel. To study the percolation law of fracturing plugging agent in the dominant channel, high-pressure displacement experiments were conducted using natural cores under different permeability and concentration conditions of the fracturing plugging agent. The results showed that the percolation rate of the fracturing plugging agent was almost linearly related to reservoir permeability. Due to the formation of micro-fractures and crosslinking reactions, the percolation rate first increased and then decreased to a stable state. After a certain period, the pores were blocked, resulting in a sharp decrease in the percolation rate and then decayed. In addition, the higher the concentration of fracturing plugging agent, the better the core plugging performance. Moreover, when the concentration of fracturing plugging agent injected into the core exceeded 3,000 mg/L, the core permeability increased, and the breakthrough pressure evidently increased three to four times. On the basis of this, rheometer tests, scanning electron microscopy (SEM) observations, and mercury intrusion tests were performed to evaluate gelation performance, shear effect, and pore retention morphology of the crosslinking system made by mixing the injected plugging agent and residual polymer in the reservoir. The results showed that the shear action could reduce the gelling property, and the concentration of fracturing plugging agent should be >3,000 mg/L to meet the requirements of gelling. Furthermore, the viscosity of the crosslinking system reached the peak value at approximately 72 h, forming a network space structure of layered superposition, thereby increasing viscosity by 40–50 times. Finally, SEM images revealed that after the fracture plugging agent was injected into the core, the micelles were mostly concentrated in the front and middle sections. The average pore radius of the core decreased by 8.620 μm, and the average porosity decreased by 54.85%.

The aim of this study was to determine the rheological property and crystallization behavior of polylactic acid (PLA) with improved heat resistance (Ingeo™ Biopolymer 4032D) through investigation of the melt viscosity and crystallization kinetics of PLA at different process temperatures. The viscosity was measured using a rotational rheometer under conditions of shear rates of 0.01, 0.1, and 1/s. The obtained rheological data show that the viscosity tended to decrease slightly as the shear rate increases and decrease sharply as the temperature increases from 180°C to 210°C. To investigate the effect of the process temperature on the crystallization kinetics and final crystallinity of PLA, thermal analysis using isothermal differential scanning calorimetry (DSC) were also performed. The Avrami equation was successfully applied for the isothermal crystallization kinetics model. From crystallization temperature of 85°C to 120°C, we found that the Ingeo™ Biopolymer 4032D PLA had the fastest crystallization rate ( t 1/2 : 26.0 min) and the largest crystallinity (47.4%) at 100°C.

In this study, the morphological and mechanical performances of hybrid green organic and inorganic filler composites were investigated. Various hybrid reinforcements using natural waste fillers including lemon leaves and eggshells were utilized for the study. The tensile strength, tensile modulus, elongation to break, flexural strength, and flexural modulus were investigated for the composites with polypropylene matrix. The results revealed that eggshells composites had the best values for both tensile and flexural tests while lemon leaves composites had the lowest values. However, the hybrid filler (lemon leaves-eggshells) had intermediate values. The poor properties of lemon leaves were attributed to the agglomeration and weak bonding presented by the morphological analysis of the hybrid composites.

In this report, PEDOT composite films were prepared by in situ electrochemical polymerization. 1-Ethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide (EMI-TFSI) was used as an ionic liquid dopant for PEDOT:PSS films. Subsequently, these PEDOT:PSS/EMI-TFSI films were compared with PEDOT:PSS films based on their morphology, structure, electrochromic properties, and optical properties at different deposition voltages and deposition times. It was observed that the addition of EMI-TFSI enhanced all the aforementioned properties of the films. PEDOT:PSS/EMI-TFSI films were seen to have a larger ion diffusion coefficient (1.38 × 10 −20  cm 2 ·s −1 ), a wider color change range (43.48%), a shorter response time (coloring response time = 1.2 s; fade response time = 2 s), and a higher coloring efficiency (189.86 cm 2 ·C −1 ) when compared with normal PEDOT:PSS films. The introduction of EMI-TFSI in the films ultimately resulted in superior electrochemical and optical properties along with higher stability.

The quartz fiber-reinforced epoxy resin-based composites (QFRECs) were fabricated by resin transfer molding (RTM), and then the effect of laser ablation on the structure and dielectric properties of the prepared composite was investigated. The FTIR, XRD, and SEM analyses show that the thermal decomposition, pyrolysis, carbonization, graphitization, and ablation occurred on the surface of the epoxy resin under laser irradiation. The in situ produced carbon endows the QFREC with an improved dielectric constant, which increases maximally from 3.3 to 4.5 in the range of 7–17 GHz under the energy intensity of 226 W·cm −2 . Compared with short-time irradiation (5 s), long-time irradiation (10 s) exhibits a greater impact on the dielectric constant due to the formation of crystal graphite at prolonged high temperature. Meanwhile, the rough and deep pits are inclined to form onthe surface of the long-time irradiative composite. These findings provide guidance for the practical application of QFREC as wave-transmitting materials.

The influence of alumina (Al 2 O 3 ) content and diameter on the viscosity characteristics of the alumina/linear low-density polyethylene (Al 2 O 3 /LLDPE) composites was discussed. The composites were fabricated by melt mixing with the two-rotor continuous mixer. The equivalent surface average particle diameter ( d ¯ A {\bar{d}}_{\text{A}} ) of Al 2 O 3 was calculated by the scanning electron microscopic (SEM) images of samples. The steady-state and dynamic rheological measurements were used to study the evolution of viscosity parameters. With the Carreau model fitting to the steady-rate rheological data, zero-shear viscosity η 0 , time constant λ , and power law index n of composites were obtained. On this basis, an optimized Carreau model was established by studying the changes of these parameter values. The rheological result presented that the parameter values ( η 0 , λ , and n ) were linearly proportional to the filling content of Al 2 O 3 particles for nano-Al 2 O 3 /LLDPE composites. However, these parameters were, respectively, related to d ¯ A {\bar{d}}_{\text{A}} , d ¯ A 2 {\bar{d}}_{\text{A}}^{2} , and d ¯ A 3 {\bar{d}}_{\text{A}}^{3} for micron-Al 2 O 3 /LLDPE composites.

Climate change makes it imperative to use materials with minimum global warming potential. The fourth-generation blowing agent HCFO-1233zd-E is one of them. The use of HCFO allows the production of polyurethane foam with low thermal conductivity. Thermal conductivity, like other foam properties, depends not only on the density but also on the cellular structure of the foam. The cellular structure, in turn, depends on the technological parameters of foam production. A comparison of pouring and spray foams of the same low density has shown that the cellular structure of spray foam consists of cells with much less sizes than pouring foam. Due to the small size of cells, spray foam has a lower radiative constituent in the foam conductivity and, as a result, a lower overall thermal conductivity than pouring foam. The water absorption of spray foam, due to the fine cellular structure, also is lower than that of pouring foam. Pouring foam with bigger cells has higher compressive strength and modulus of elasticity in the foam rise direction. On the contrary, spray foam with a fine cellular structure has higher strength and modulus in the perpendicular direction. The effect of foam aging on thermal conductivity was also studied. Graphical abstract Polyurethane foams obtained with low global warming potential and low ozone depletion potential blowing agent.

This study aims to improve the hydrophobic properties and corrosion resistance of fluorinated acrylate coatings. The surface of nano-SiO 2 was modified by the silicone coupling reagent (KH-570), and the reactive functional groups were introduced to modify fluorinated acrylates. The functionalized SiO 2 -modified waterborne fluorinated acrylate emulsion was prepared by free polymerization with dual initiators. The structure of the polymer was analyzed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectro-meter ( 1 H-NMR), X-ray photoelectron spectroscopy (XPS) and Waters gel chromatography (GPC). The properties of the films and coatings were analyzed by contact angle, atomic force microscopy, scanning electron microscopy, and electrochemical analysis. The results showed that the contact angle reached 120° when the SiO 2 content was 3%, the electrochemical impedance value reached 1.49 × 10 7  Ω·cm 2 , and the pencil hardness was 3H. Graphical abstract In this study, KH-570 was used to modify the surface of nano-SiO 2 to obtain functionalized nano-SiO 2 , and then fluorine-containing acrylic monomer was grafted onto the surface of nanomaterials. This study effectively improved the surface roughness of the coating, and SiO 2 particles can fully fill the gaps of the coating, thereby improving the hydrophobicity and anticorrosion ability of the coating.

In this study, different processes are performed for the preparation of natural rubber latex (NRL)/silica composites. A novel approach is to use spray sputtering technology combined with in situ method to improve the dispersion of silica in rubber latex matrix and further improve the properties of vulcanizates. Results show that in situ silica in rubber matrix prepared from NH 4 Cl and Na 2 SiO 3 has better Payen effect than other processes. Meanwhile, when the in situ silica reached 10 phr in the rubber matrix, the dosage can suitably match the dispersion capacity of the spray sputtering process with superior comprehensive mechanical properties. Compared with the traditional precipitation method, the tensile strength and tear strength of the silica/NR composites prepared by spray sputtering technology combined with in situ method were increased by 34.7% and 19.7%.

Popularly, the application of biodegradable polymer film can resolve polyethylene (PE) film residual “white pollution” but it is unclear when the degradable film begins to degrade in different regions. To solve these issues, a total of 32 papers on the subject of the relative film coverage durability (RFCD) on positive covering effect from papers published before July 2019 were selected and analyzed by meta-analysis. The results showed that the tobacco relative yield (RY), relative profit (RP), and relative fine and medium (RFM) ratio improved by 11.2%, 12.9%, and 12%, respectively, under fully covered compared with the uncovered tobacco in the whole growth period. The RY 0.33<RFCD<0.66 and RP 0.33<RFCD<0.66 of removed PE treatments significantly improved by 4.3% and 4.0%, respectively, compared with the fully covered treatments. The RFM did not show significance with the fully covered treatments. The RY 0.33<RFCD<0.66 was the highest in the low altitude (less than 1,000 m) region; however, the RY under the fully covered treatments was the greatest in the high altitude (more than 1,000 m) region. Random effect analysis showed that the model between RFCD and RY was RY = 1 + 0.275 × (1 − RFCD) – 0.357 × (1 − RFCD) 2 , and the RY max (1.053) was reached with RFCD = 0.62 (removed PE after covering for 80 days) in the high-altitude region. In the low altitude region, RFM = 1 + 0.205 × (1 − RFCD) − 0.246 × (1 − RFCD) 2 , and the RFM max (1.043) was obtained under the treatments with RFCD = 0.58 (removed PE after covering for 75 days). The findings determined the optimum film (PE) covering period of tobacco and provided a crucial theoretical basis for the degradable polymer film material design, synthesis, and manufacturing in different regions.

Parylene C (PC) films have been widely used in many fields, such as metal anti-corrosion, electronic packaging, etc. However, the relatively poor mechanical properties and the deteriorated water barrier performance due to the easy fracture under external stress have restricted their application. It is a relatively simple and good method to maintain the water vapor barrier and enhance the mechanical properties of PC film by covering a flexible coating on its surface. In this work, a new polyurethane acrylate (PUA) coating was prepared and coated on the PC film by ultraviolet curing technology to form the PC/PUA composite film. The results showed that the PUA coatings could improve the water vapor barrier and mechanical properties of the PC film simultaneously. The water vapor transmittance rate was reduced from 1.1791 g·(m −2 ·day −1 ) of the original PC film to 0.5636 g·(m −2 ·day −1 ) of the PC/PUA composite film. The elongation at break and the impact energy were increased to 48.36% and 41.67%, respectively, which would widen the application of PC films in the fields of flexible electronics or smart wear.

In this paper, porous alumina continuum (PAC) was prepared with alumina powders (APs) by the gel-casting method and was applied to obtain silicone elastomer (SR) composites (PAC/SR) by the impregnating process. The structure was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of PAC on thermal conductivity and dielectric permittivity of PAC/SR composites were studied in comparison with AP/SR composites. When the alumina content was 14 vol%, the thermal conductivity of the PAC/SR composites reached 0.84 W·(m·K) −1 , which was 3.1 times higher than that of the AP/SR composites. The thermal conductivity of PAC/SR and AP/SR was simulated by theoretical models, and the interfacial thermal resistance was calculated by effective medium theory, which indicated the advantages of PAC in enhancing the thermal conductivity of SR-based composites and the reduced interfacial thermal resistance between PAC and SR. Graphical abstract PAC provided numerous interpenetrated channels for the access of SR and prompted the formation of interconnected three-dimensional networks for remarkable improvement on the thermal conductivity of PAC/SR composites.

In this study, a high-activity Zn–Co double metal cyanide complex was synthesized and used to catalyze the ternary polymerization of carbon dioxide, propylene oxide, and itaconic anhydride to produce a new class of polypropylene carbonates characterized by excellent performance and low ether content. The number average molecular weight of the terpolymer was as high as 2.14 × 10 5  g·mol −1 , and the polydispersity index was as high as 1.58. In the case of PPCIAn 3 , the 5% weight loss temperature increased by 70°C, the total weight loss temperature increased by 100°C, the tensile strength increased by 6.6 MPa, and the elongation at break decreased to 14.5% with respect to traditional polypropylene carbonate. The apparent efficiency of the catalyst was as high as 45.79 g polymer /g catalyst , indicating its high catalytic activity. 1 H-NMR spectrometry, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, and in situ Fourier-transform infrared spectroscopy were used to characterize the polymerization process and the structural properties of the obtained terpolymers.

Fumed silica-filled polypropylene (PP)-based nanodielectrics were studied in this work. To not only improve the dispersion of the silica but also introduce deep charge traps into the polymeric matrix, five types of modified silicas were manufactured with different surface modifications. The modified silica surfaces comprise an inner and a surface layer. The inner layer contains a polar urethane group for tailoring the charge trap properties of the PP/propylene–ethylene copolymer nanocomposites, whereas the surface layer consists of hydrocarbons (ethyl-, tert -butyl-, cyclopentyl-, phenyl-, or naphthalenyl moieties) in order to gain a good dispersion of the silica in the unpolar polymer blend. Scanning electron microscopic pictures proved that these tailored silicas show a much better dispersion than the unmodified one. Thermally stimulated depolarization current measurements revealed the ability of the silica to introduce deep charge traps with low trap density. The trap depth distribution depends on the type of the unpolar surface layer consisting of the different hydrocarbons. Among these five differently modified silicas, the introduction of the one with a surface layer consisting of tert -butyl moieties resulted in the lowest charge injection and the lowest charge current in the nanocomposite, proving good dielectric performance. Additionally, this silica exhibits good dispersion in the polymeric matrix, indicating a promising performance for nanodielectric application.

Methotrexate (MTX) is widely used for the treatment of various types of cancer; however, it has drawbacks such as low solubility, lack of selectivity, premature degradation, and side effects. To solve these weaknesses, a hydrogel with the ability to contain and release MTX under physiological conditions without burst release was synthesized. The hydrogel was fabricated with a poly( ɛ -caprolactone)- b -poly(ethylene glycol)- b -poly( ɛ -caprolactone) (PCL–PEG–PCL) triblock copolymer, synthesized by ring-opening polymerization. The characterizations by proton nuclear magnetic resonance spectroscopy and Fourier-transform infrared spectrometry confirmed the copolymer assembly, whereas the molecular weight analysis validated the PCL 2000 –PEG 1000 –PCL 2000 structure. The copolymer aqueous solution exhibited sol–gel phase transition at 37°C and injection capacity. The hydrogel supported a load of 1,000 μg MTX·mL −1 , showing a gradual and sustained release profile of the drug for 14 days, with a delivery up to 92% at pH 6.7. The cytotoxicity of the MTX-loaded hydrogel was performed by the methyl thiazole tetrazolium assay, showing a mean inhibitory concentration of 50% of MCF-7 cells (IC 50 ) at 43 µg MTX·mL −1 . Graphical abstract MTX is loaded and released in a controlled manner over 14 h, under physiological conditions, from an amphiphilic triblock copolymer with a sol–gel phase change at 36.5°C.

This paper studies the aging mechanism of elastomeric gaskets made from silicone rubbers in simulated proton exchange membrane fuel cells (PEMFCs) in humid, acidic, and high-temperature environments. The changes in the surface morphology are observed using optical microscopy. Attenuated total reflection Fourier transform infrared spectroscopy (AFT-FTIR) and X-ray photoelectron spectroscopy (XPS) are used to investigate the changes in the chemical molecular structure. The stress relaxation test is conducted to characterize the decay process of the mechanical properties. The results indicate that cracks appear on the surface and that the aging mechanism is mainly due to decomposition in the backbone and hydrolysis of the crosslinking. The stress relaxation modulus decreases as the acid concentration increases, which suggests a decrease in elasticity and an increase in brittleness. A master curve that relates time and concentration is constructed. Based on this inference, the experimental time can be shortened by about four times.

To study the effect of the melt-draw ratios (MDRs) on the structure and properties of the poly(4-methyl-1-pentene) (PMP) film, the crystal structure evolution and mechanical properties of the PMP film with an MDR of 40–160 were characterized using scanning electron microscopy, differential scanning calorimetry, wide-angle X-ray scattering, and mechanical test. The results show that with the increase of MDR, the spherulite to platelet transition occurs in the PMP. When the MDR exceeds 100, a parallel platelet structure appears. Due to the side chains, with the increase of MDR, the distribution density of tie chains in PMP decreases and the entanglement density of amorphous chains increases. This leads to a decrease in the yield strength and the strain hardening becomes noticeable. Although the crystalline network becomes loose due to the decrease in tie chain density, the elastic recovery (ER) value still increases with the increase of MDR. This result indicates that the entanglement density of the amorphous region greatly contributes to the ER.

Polymer membrane-based gas separation is a superior economical and energy-efficient separation technique over other conventional separation methods. Over the years, different classes of polymers are investigated for their membrane-based applications. The need to search for new polymers for membrane-based applications has been a continuous research challenge. Aromatic polyamides (PAs), a type of high-performance materials, are known for their high thermal and mechanical stability and excellent film-forming ability. However, their insolubility and processing difficulty impede their growth in membrane-based applications. In this review, we will focus on the PAs that are investigated for membrane-based gas separations applications. We will also address the polymer design principal and its effects on the polymer solubility and its gas separation properties. Accordingly, some of the aromatic PAs developed in the authors’ laboratory that showed significant improvement in the gas separation efficiency and placed them in the 2008 Robeson upper bound are also included in this review. This review will serve as a guide to the future design of PA membranes for gas separations.

3D printing belongs to the emerging technologies of our time. Describing diverse specific techniques, 3D printing enables rapid production of individual objects and creating shapes that would not be produced with other techniques. One of the drawbacks of typical 3D printing processes, however, is the layered structure of the created parts. This is especially problematic in the production of optical elements, which in most cases necessitate highly even surfaces. To meet this challenge, advanced 3D printing techniques as well as other sophisticated solutions can be applied. Here, we give an overview of 3D printed optical elements, such as lenses, mirrors, and waveguides, with a focus on freeform optics and other elements for which 3D printing is especially well suited.

Recently, bicomponent fibers have been attracting much attention due to their unique structural characteristics and properties. A common concern was how to characterize a bicomponent fiber. In this review, we generally summarized the classification, structural characteristics, preparation methods of the bicomponent fibers, and focused on the experimental evidence for the identification of bicomponent fibers. Finally, the main challenges and future perspectives of bicomponent fibers and their characterization are provided. We hope that this review will provide readers with a comprehensive understanding of the design and characterization of bicomponent fibers.

A bibliometric approach allowed us to study the global research trend on the impact of ionizing irradiations on polymers from 1975 to 2019. The investigation revealed 1,015 publications with growing interest since 1990. The research is split into three main categories: polymer science, nuclear science technology, and chemistry physical. The three main ionizing irradiations studied in this research are gamma, electron beam, and X-ray irradiations. The impact of ionizing irradiations on polymers under gamma irradiation is the most commonly studied field with 578 publications among the 1,015 publications. Electron beam irradiation is the second most studied field followed by X-ray irradiation. Whatever the irradiation modalities, publications focus on material degradation and material improvement studies.

Poly(butylene succinate) (PBS) has good impact strength and high elongation at break. It is used to toughen biodegradable poly(lactic acid) (PLA) materials because it can considerably improve the toughness of PLA without changing the biodegradability of the materials. Therefore, this approach has become a hotspot in the field of biodegradable materials. A review of the physical and chemical modification methods that are applied to improve the performance of PLA/PBS blends based on recent studies is presented in this article. The improvement effect of PLA/PBS blends and the addition of some common fillers on the physical properties and crystallization properties of blends in the physical modification method are summarized briefly. The compatibilizing effects of nanofillers and compatibilizing agents necessary to improve the compatibility and toughness of PLA/PBS blends are described in detail. The chemical modification method involving the addition of reactive polymers and low-molecular-weight compounds to form cross-linked/branched structures at the phase interface during in situ reactions was introduced clearly. The addition of reactive compatibilizing components is an effective strategy to improve the compatibility between PLA and PBS components and further improve the mechanical properties and processing properties of the materials. It has high research value and wide application prospects in the modification of PLA. In addition, the degradation performance of PLA/PBS blends and the methods to improve the degradation performance were briefly summarized, and the development direction of PLA/PBS blends biodegradation performance research was prospected.

Overuse of polymer products has led to severe environmental problems, which are threatening survival of creatures on earth. It is urgent to tackle enormous polymer wastes with proper cycling methods. Pyrolysis of polymers into high-value chemicals and fuels is displaying great potential to address the white pollution issue. In this study, we focus on chemical recycling of polystyrene, an important polymer in our everyday life, into valuable chemicals through simple pyrolysis strategy under nitrogen protection. It is found that yield of liquid product from polystyrene pyrolysis achieves as high as 76.24%, and there exists single component in the liquid product, which has been identified as styrene through hydrogen nuclear magnetic resonance spectra. Moreover, we propose monomer dissociation mechanism to explain the pyrolysis process of polystyrene based on the structure of polystyrene and experimental results.

Uncontrollable bleeding is still the main cause of post-traumatic deaths due to the blood loss. Moreover, infectious complication of wound is also still a challenging problem for wound healing. Nevertheless, the currently available hemostasis drugs or materials cannot stanch bleeding well due to single function, slow in effectiveness, adhere to wounds easily, poor gas permeability, etc. Therefore, it is of a great significance to utilize a biomedical hemostatic material that can stop bleeding quickly, preventing from bacterial infections, and with good biocompatibility properties. Herein chitosan (CS) was modified with gallic acid (GA) and thrombin (TB) to prepare an antibacterial hemostatic composite dressing. The CS-based composite hydrogel dressing was obtained by acylation modification, ultraviolet curing crosslinking method and physical mixing. The in vitro results showed that our prepared CS-based composite hydrogel has obvious burst release and good degradation property. Moreover, the in vivo results showed that it has a strong antibacterial property that is much better than single CS, and it can stop bleeding in 1 min which can promote wound healing. Therefore, the findings of this study is expected to contribute to the future designing of biomedical hemostatic materials with improved properties.

In this study, a novel CT contrast agent used by rectal administration is developed for targeting intestinal imaging. Iopamidol, an iodinated contrast agent, is loaded in chitosan (CS) nanospheres modified by Anti-5-HT3R (AH) antibody. The obtained AH-CS-I nanospheres (AH-CS-I Ns) would combine to 5-HT3 receptors highly expressed on the gastrointestinal mucosal, enhancing the intestinal-targeting ability of the contrast agent. The AH-CS-I Ns were administered by the rectal route for intestinal CT imaging, and FITC-labeled AH-CS-I Ns were prepared for investigating the in vivo distribution of the contrast agent. As a result, obvious contrast enhancement could still be observed at 6 h post administration because of the poorly absorption of enteral AH-CS-I Ns. Unlike the intravascularly administered agents, AH-CS-I Ns would not accumulate in the kidney and induce adverse reactions. Therefore, this technology has potential applications in the examination of intestinal diseases and could reduce the side effect of commercial iopamidol.

An improvement of ecological conscience currently has increased the consciousness of researchers in reducing the processing time and cost of solvent for the dissolution of cellulose. Latterly, ionic liquids have been employed to process cellulose as they are recyclable and nonvolatile. Besides that, biopolymers such as chitosan, chitin, starch, protein, and cellulose acetate can also be processed by using ionic liquids for diverse applications. In this short review, examples of imidazolium-based ionic liquids that are commonly used for the dissolution of cellulose are implied. Furthermore, examples of organic liquids that are utilized as co-solvents for ionic liquids were revealed. In addition, examples of imidazolium-based ionic liquid/co-solvent mixtures utilized in the dissolution of cellulose and other biopolymers are also demonstrated. The properties and applications of cellulose and its blends regenerated from different types of cellulose/imidazolium-based ionic liquid/co-solvent solutions are also shortly reviewed. The information acquired from this review gives a better understanding of the changes in the properties of regenerated cellulose and regenerated cellulose blends. In addition, this short review serves as a model basis for the creation of novel applications of regenerated cellulose and regenerated cellulose blends by utilizing imidazolium-based ionic liquid/co-solvent mixtures.

In this study, the impact of particle form of the Cannabis indica plant biofibers and the fiber’s surface tailoring on the physical, thermal, dielectric, and mechanical properties of unsaturated polyester composite specimens manufactured utilizing nonconventional materials were investigated. The mechanical properties such as compressive, flexural, and tensile strengths of the composite specimens were noticed to increase after functionalization of biofiber with acrylic acid and maximum enhancement was found at 20% of biofiber sacking. The physical characterization was concentrated on the assurance of the dielectric constant, dielectric strength, dielectric loss, moisture absorption, chemical resistance, percentage of swelling, limiting oxygen index, and biodegradation of polymer composites under red soil. An increase in dielectric strength from 28 to 29 kV, limiting oxygen index values from 19% to 23%, and moisture/water absorption behavior was noted for resulted bio-composites after surface tailoring of biofiber. To assess the deterioration of the polymeric materials with the temperature, differential scanning calorimetric and the thermogravimetric tests were carried out and enhancement in thermal stability was noted after fortification of polyester composites with functionalized biofiber. Graphical abstract Cellulosic biofibers’ surface modification and its utilization for the development of polyester matrix-based biocomposites.