Volume 19, Issue 1

A novel chemical-consolidation method based foam amino resin system of sand control systems in the oilfield is reported. This sand control technique is more superior to the conventional method owing to its advantages such as the outstanding resistance and lower density as well as simple process preparation. The apparent density of the foam resin system ranges from 0.528 g/cm 3 to 0.634 g/cm 3 at room temperature. Moreover, the system has excellent foaming properties and excellent compatibility with the formation fluids. In addition, the foam amino resin sand consolidation system was optimized and investigated. Simultaneously, the sand-fixing performance of the foam resin system was comprehensively assessed. The optimized conditions are as follows: curing temperature, 60°C; curing time, 12 h; consolidated core compressive strength, 6.28 MPa. Furthermore, the consolidated core showed remarkable resistance to the formation fluids. In summary, the foam resin system effectively met the requirements of the sand control and the horizontal wells in the oilfield. Graphical Abstract

In this paper, the bottom fire behaviour of 25 cm × 25 cm × 5 cm natural rubber (NR) latex foam with uniformly distributed 6 mm diameter holes was investigated experimentally in a small-scale experimental platform under bottom ventilation. The bottom fire behaviour was analysed. The results show that the burning process of the thermally thick NR latex foam under bottom ventilation conditions can be divided into three stages: initial growing, full development, and decay. A deflagration covered the entire rear surface was observed at 308 s. The burning balls moving at a speed of 0.15 m/s were observed after the bottom ignition and they moved from the center to the sides along with the expansion. The mass loss rate of the sample was accelerated dramatically from 0.2 g/s to 0.5 g/s when the bottom surface was ignited at 308 s.

In this study, the salicylaldehyde hydrazone was bonded onto the side chains of poly (styrene-co-butyl acrylate), firstly obtaining a series of novel Schiff base-functionalized polymers. and using the base-containing polymers as macromolecular ligands through further reaction with EuCl 3 /YbCl 3 ·6H 2 O, a series of polymer-rare earth complexes based on Eu(III)/Yb(III) ion were successfully prepared. The structures of the schiff base-containing polymers and their corresponding complexes were characterized by means of infrared spectra and UV spectra. The thermal properties of the functionalized polymers and complexes were investigated by TGA, and the fluorescence properties of the complexes were also researched by fluorescence spectrum. The experimental results show that the complexes have fine thermal stability likely because of the bidentate chelate effect of base-containing polymer and the conjugative effect of salicylaldehyde hydrazone group on the side chain of poly (styrene-co-butyl acrylate). More important, the salicylaldehyde hydrazone group on the side chains of poly(styrene-co-butyl acrylate) can efficaciously sensitize the fluorescence emission of the center ion due to effective intramolecular energy transfer. All the Eu(III)/Yb(III) complexes exhibit characteristic photoluminescence peaks in the visible region. The fluorescence excitation spectra of the complexes were obtained by monitoring the emission of Eu 3+ /Yb 3+ ion at 497 nm, and the peak at 433 nm was found to be the optimal excitation peak. The concentration of salicylaldehyde hydrazone group was changed gradually with the variation of the molar ratio between the butyl acrylate and styrene (1:0.5; 1:1; 1:1.5; 1:2; 1:2.5), and the differences in their fluorescent intensity were followed, and the fluorescence intensity was very weak when the molar ratio of the butyl acrylate to styrene is equal to 1:2.5, while the fluorescence intensity reached a maximum value in the molar ratio of 1:1.

In this paper, the unsaturated hydrogen bonds (H-bonds) of the bio-based polyamide 56 (PA56) with an odd-even unit structure were analyzed by infrared spectroscopy. It was proved that the bio-based PA56 had less saturated H-bonds, which became attenuated and blue-shifted at the temperature exceeding 260°C. Besides, as H-bond was decayed and broken, new unsaturated H-bonds readily formed. Moreover, the experimental results obtained strongly indicate that the unsaturated H-bonds of bio-based polyamide 56 could react with polar metal oxides. Besides, the intercalation of montmorillonite was found to have a significant influence on the hydrogen bond between polymer chains.

The effects of phosphate nucleating agent (NA), carboxylate nucleating agent (MD), rosin type nucleating agent (WA) and sorbitol nucleating agent (NX) on crystallization behavior of isotactic polypropylene were investigated by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The results showed that different structure nucleating agents significantly affected the crystallization kinetics, rate and temperature of polypropylene. Among them, half crystallization time of NX nucleating agent was the shortest, which was 53.4 seconds, and the crystallization temperature was the highest, reaching 129.8°C.

In this study, ultrahigh-molecular-weight polyethylene (UHMWPE) fibres, modified by acetic acid, sulfuric acid and water at a ratio of 20:25:2 for different time periods and modified UHMWPE/EP composites were prepared. The micromorphology, chemical composition, contact angle, H sample extraction, tensile properties and bending performance of the composite material of the UHMWPE fibres before and after modification were tested and analysed. The results show that, after the UHMWPE fibres were treated with the modified liquid, the surface roughness of the fibre increased, the contact angle decreased, and the surface chemical composition and species significantly changed; the mechanical properties of the composites are best when the fibres were treated for 9 min. For the same fibre content, the specific strength, specific modulus and bending load of UHMWPE composites treated for 9 min were increased by 16.7%, 82.9% and 55.3%, respectively, compared with untreated samples.

In the field of polymer processing, disperse phase exhibited better dispersion and distribution performance in elongational field rather than shearing field. This property commonly brought a better functional feature for polymer composites. It could also be applied to Nano-ZnO/IFR synergetic flame retarded polypropylene/ ethylene-propylene-diene monomer composites. An experiment was designed to study the mechanism of improving flame retardant properties. In the experiment, the same formulas of composites were extruded by vane extruder (represents elongational field) and three-screw extruder (represents shearing field). Then Kissinger method and Flynn-Wall-Ozawa method were used to mutually proved that Nano-ZnO with better dispersion condition catalysed a more intense esterification of IFR in the whole thermal degradation process.

A new conductive composite composed of nanoscale carbon black (CB) and poly(3,4-ethylenedioxythiophene) (PEDOT) was prepared by a simple in-situ polymerization. The morphology of the composite was characterized by scanning electron microscopy and transmission electron microscopy. The structure and thermal stability were examined by Fourier transform infrared spectroscopy and thermal gravimetric analysis, respectively. The results indicated that the addition of CB improved the agglomerated state of PEDOT. On the one hand, CB effectively hindered the agglomeration of PEDOT during the polymerization. Thus, the obtained CB-PEDOT composite dispersed well in solution, which can facilitate the reprocessing of CB-PEDOT. On the other hand, CB covered most of the surface of PEDOT, which enhanced the electrical conductivity of CB-PEDOT. Furthermore, the interfacial interaction between CB and PEDOT improved the thermal stability of CB-PEDOT. The findings of this research suggest that CB can replace polyelectrolyte poly(styrenesulfonic acid) (PSS) to achieve reprocessable materials for certain applications.

Boron nitride (BN) coated with sulfonated poly-arylene ether nitrile (SPEN) (BN@SPEN) was used as additive to enhance the thermal conductivity of polyarylene ether nitrile. BN@SPEN was prepared by coating BN micro-platelets with SPEN through ultrasonic technology combined with the post-treatment bonding process. The prepared BN@SPEN was characterized by FTIR, TGA, SEM and TEM, which confirmed the successful coating of BN micro-platelets. The obtained BN@SPEN was introduced into the PEN matrix to prepare composite films by a solution casting method. The compatibility between BN and PEN matrix was studied by using SEM observation and rheology measurement. Furthermore, thermal conductivity of BN@SPEN/PEN films were carefully characterized. Thermal conductivity of BN@SPEN/PEN films was increased to 0.69 W/(m⋅K) at 20 wt% content of BN@SPEN, having 138% increment comparing with pure PEN.

The surface modification of polyacrylonitrile (PAN) fibers with boric acid was utilized to modulate the homogeneity of the radial structure of the PAN fibers during thermal stabilization. Exothermic peaks of the fibers were put off by boric acid, and unreacted nitrile groups of the oxidized PAN fibers increased with the boron content, indicating that boric acid on the fiber surface had an retardant effect on the thermal stabilization of PAN fibers. The relative skin thicknesses of the oxidized PAN fibers were quantitatively measured by sulfuric acid etching and SEM observation. The value increased obviously with the boron content, which could be further elevated by increasing stabilization time or decreasing stabilization temperature. Oxidized PAN fibers with more homogeneous radial structure can thus be obtained with the modification of boric acid, which might be beneficial for the preparation of high performance carbon fibers. Graphical Abstract

In the past few decades, stem cell transplantation has been generally accepted as an effective method on the treatment of tissue and organ injury. However, the insufficient number of transplanted stem cells and low survival rate that caused by series of negative conditions limit the therapeutic effect. In this contribution, we developed an injectable hydrogel composed of sodium alginate (SA) and Type I collagen (ColI), as the tissue scaffold to create better growth microenvironment for the stem cells. Compared the traditional SA scaffold, the ColI/SA hydrogel inherits its biomimetic properties, and simultaneously has shorter gelation time which means less loss of the transplanted stem cells. The mesenchyma stem cell (MSC) culture experiments indicated that the ColI/SA hydrogel could prevent the MSC apoptosis and contributed to faster MSC proliferation. It is highlighted that this ColI/SA hydrogel may have potential application for tissue regeneration and organ repair as the stem cell scaffold. Graphical Abstract

To exploit the application of calcium montmorillonite (CaMt) and improve the flame resistance of polystyrene (PS), two kinds of long carbon chain quaternary ammonium bromides with different spatial effect (i.e., cetyltrimethyl ammonium bromide (CTAB) and didodecyl dimethyl ammonium bromide (DDAB)) were used to intercalate CaMt for yielding corresponding organic calcium montmorillonite (CaOMt). The PS nanocomposites containing CaOMt (PS/CaOMt) were prepared by melt blending method. The effects of CaOMt on flame resistance, thermal stability, tensile properties and interfacial adhesion of PS/CaOMt were investigated. The results showed that both CTAB and DDAB were intercalated into CaMt to get CaOMt with an exfoliated/intercalated structure, which could endue good interfacial adhesion and thermal stability for PS/CaOMt. All peak values of flame resistance parameters of PS/CaOMt decreased and corresponding combustion times were postponed obviously. Moreover, Young’s modulus of DDAB-intercalated PS/CaOMt was improved by 49.1% while its tensile strength kept at the same level as PS. Graphical Abstract

Recently, great attention has been paid to nano-composites of cellulose, due to their unique structure as a most abundant natural polymer with having exceptional properties such as renewable, biodegradable and high specific tensile strength, aspect ratio, and Young’s modulus. Prominent cellulose is naturally present in plant lignocellulosic biomass as a biocomposite made of cellulose, hemi-celluloses, lignin, etc. In addition, it can be extracted from other natural sources including bacteria, algae, and sea animals. Microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), and nanofibrillated cellulose (NFC) is an emerging renewable nanomaterial that has various applications, such as food, paper production, industrial and pharmaceutical biomaterials. The surface modification on NCC can improves its disperse ability in different solvents and its utilization in protein immobilization, tissue engineering, drug delivery, and inorganic reaction template. Therefore, based on recent studies, this review illustrated considerable progresses with addressing medicinal properties involving antimicrobial and biocompatibility of nano-cellulose (NC) in the case of wound healing.

The effect of high salt concentration and pH on the binding of globular protein to polycation at different molar masses has been investigated by dynamic light scattering (DLS), turbidimetry and electrostatic modeling for the protein. In dilute concentration regime, DLS and pH titrations showed three remarkable pH transitions: pH c , the pH where soluble complexes of bovine serum albumin (BSA) and linear synthetic Polyethylenemine (PEI) are formed, pH c ’ presents the end of primary soluble complex and pH φ presents the first appearance of microcoacervate droplets. All pH transitions increase with increasing NaCl concentration. The Adaptive Poisson-Boltzmann Solver (APBS) identify with precision the functional sites at the surface of BSA and shows that the strength of electrostatic interactions depends hugely on the variation of pH and ionic strength. At a very high concentration of salt, no remarkable effect on a mixture formed of a long chain of polycation and globular protein. Graphical Abstract

Nowadays, reducing the hazards of bayer red mud (BRM) is an important research direction in the fields of environmental and safety. In this article, Mg/Al/Fe ternary layered double hydroxides (Mg/Al/Fe-LDHs) were synthesized successfully by a co-precipitation method based on introducing Mg 2+ into the BRM suspension. The thermogravimetric analysis (TGA) results showed that the decomposition rate of LDHs is higher than that of BRM, which indicates that LDHs can absorb more heat than BRM during the decomposition process. Subsequently, BRM and LDHs were added into the ethylene vinyl acetate (EVA) to investigate its effects on reducing flammability of the composites. The cone calorimeter test (CCT) results demonstrated that 50 wt% LDH-B can make the peak value of HRR (PHRR) decrease from 1694.8 kW/m 2 (EVA) to 199.2 kW/m 2 (ELDH2). The smoke density test (SDT) results showed that the luminous flux of ELDH2 is nearly 95% at the end of test with a pilot flame, which is much higher than that of EVA and EBRM. The thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) results confirmed that LDHs can improve the thermal stability of composites and reduce the production of some toxic gases. Compared with BRM, the improved flame retardancy of Mg/Al/Fe-LDHs is ascribed to the introduction of Mg 2+ , which offering an enhanced catalytic carbonization capability, as well as the physical barrier effect of char residue layer catalyzed by the lamellar LDHs

Developing more organic nucleating agent with different molecular structure is very instructive to improve the crystallization of poly(L-lactic acid) (PLLA) and explore the crystallization mechanism. In this study, N, N’ -sebacic bis(hydrocinnamic acid) dihydrazide (HAD) was synthesized to serve as a nucleating agent for PLLA. The effects of HAD on the non-isothermal crystallization, melting behavior, thermal stability and optical performance of PLLA were investigated by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and light transmittance meter. The melt crystallization behavior showed that HAD was able to promote the crystallization of PLLA via heterogenous nucleation in cooling, and it was found that, upon the cooling of 1°C/min, the incorporation of 1 wt% HAD made the crystallization temperature and non-isothermal crystallization enthalpy increase from 94.5°C and 0.1 J/g to 131.6°C and 48.5 J/g comparing with the pure PLLA. Additionally, the melt crystallization significantly depended on the cooling rate and the final melting temperature. For the cold crystallization, when the nucleation density from HAD and PLLA itself was saturated, the influence of the HAD concentration on the cold crystallization process of the PLLA/HAD samples is negligible. The melting behavior after isothermal or non-isothermal crystallization further confirmed the crystallization accelerating effect of HAD for PLLA, and the appearance of the double melting peaks was attributed to the melting-recrystallization. Unfortunately, the addition of HAD decreased the thermal stability and light transmittance of PLLA.

Casein, a natural protein, has been used as a biopolymer-based resource for producing fiber. This fiber provides high comfort properties with a pH close to human skin. This study focused on evaluating the production feasibility of casein nanofiber twisted yarn with the highest protein content in the hybrid yarn, obtaining suitable spinning conditions and desirable properties of the produced yarn. The desirable yarn achieved by composing 90% casein and 10% polyethylene oxide. The yarn strengthened using several types of cross-linking methods and the best technique was obtained to spin an optimized engineered yarn. Consequently, the biodegrading test conducted on the optimized yarn (90% casein and 10% polyethylene oxide blend) in the presence of 40% di-isocyanate as strengthener additive. Observations showed that after ten days, the sample mostly degraded in the solvent and its strength massively reduced so it could be considered as an environmentally friendly, biodegradable fiber.

Ketoconazole (KTZ) was incorporated in waterborne poly(urethane-urea)s dispersions (WPUU), aiming at the production of films for drug sustained release. Dispersions based on poly(ethylene glycol- block -propylene glycol) (PEG- b -PPG) (four monomers with different contents of PEG hydrophilic segments), poly(propylene glycol), isophorone diisocyanate, dime-thylolpropionic acid and hydrazine were produced and characterized by apparent viscosity and average particle size (APS). Cast films-drug interaction was investigated by Fourier-Transform infrared spectrometry (FTIR). In vitro dissolution assays were performed in simulated gastrointestinal juices, followed by application of kinetic models. Stable pseudoplastic dispersions, with APS between 27 to 320 nm were obtained. FTIR from KTZ-loaded films indicated interactions between polymer and drug. In vitro release of KTZ was achieved above 80%, notably influenced by PEG-based segments content up to 2 h, followed by sustained release for 8 h. Higuchi’s and first-order equations described the drug kinetic profile, as diffusion of the drug and erosion of the swollen polymer, respectively. Graphical Abstract

Polyimide (PI)/mica hybrid films were successfully prepared by in situ condensation polymerization method, in which the mica particles were modified by coupling agent γ-aminopropyltriethoxy silane (APTS) to strengthen the interaction between the mica particles and PI matrix. The morphology, structure, thermal and mechanical properties as well as dielectric properties of PI films were systematically studied via Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR spectrometer), Thermal gravimetric analysis (TGA), tensile experiments, Thermal mechanical analyzer (TMA), impedance analyzer, etc. The results indicated that the mica particles were dispersed homogeneously in PI matrix, leading to an improvement of the mechanical property, thermal stability and hydrophobicity. It was novel to notice that hybrid films exhibited low coefficient of thermal expansion (CTE) and low dielectric constant simultaneously. The CTE and dielectric constant of hybrid film dropped to 25.36 ppm/k and 2.42 respectively, in the presence of 10 wt% mica into polyimide matrix.

Cylindrical-electrode-assisted solution blowing spinning (CSBS) is a novel method for preparing polymer nanofibers by using air-stretch and electrostatic simultaneously, which can fabricate thinner and more uniform nanofibers than the traditional solution blowing spinning (SBS). In this work, the effects of processing parameters including length of cylinder (LC), needle to cylinder distance (NCD) and left face of cylinder to collector distance (CCD) on the CSBS nanofiber diameter were investigated. The results are as follows: when the NCD decreased, the fiber diameter decreased; when the LC increased, the fiber diameter decreased; the CCD didn’t significantly affect the fiber diameter. Moreover, an orthogonal experimental design was utilized to investigate the effect of injection rate, air pressure, NCD, LC, diameter of cylinder (DC), voltage and CCD on the fiber diameter and porosity of various surface layers of nanofiber web (P1, P2, and P3). The results showed that the varied range of each properties (average diameter, standard deviation of the diameter, P1, P2, and P3) was 539.121-904.149 nm, 127.903-303.253, 71.464-85.1415%, 60.32725-75.46625%, 48.23925-70.08875%, respectively. We also found the order of the influence of the above-mentioned seven process parameters on each above properties of the nanofiber web, and the corresponding optimal spinning process parameters were listed. It is well known that the fiber diameter affects the mechanical properties of nanofibers, and porosity of nano-fiber webs is an important parameter in tissue engineering, bioengineering, and filtration. The effects of CSBS process parameters on nanofiber morphology and microstructure were investigated for the first time. The conclusion of the paper can help researchers to produce high quality CSBS nanofiber and promote the wider application of this novel technology.

Cross-linked poly(acrylic acid) nanoparticles were synthesized via distillation precipitation polymerization of acrylic acid and ethylene glycol dimethacrylate withdifferent molar ratios. Spherical nanoparticles with diameters between 75 and 122 nm were synthesized and exhibited temperature and pH-responsive behaviors. However, this behavior was less pronounced for samples with higher cross-linking degrees. The potential of all nanoparticles as carriers for controlled release of doxorubicin (DOX) anti-cancer drug was examined at pH values of 1.2, 5.3 and 7.4. An obvious alleviation in burst release behavior and the amount of cumulative drug release was seen for all nanoparticles as the pH of the medium and the cross-linking degree of nanoparticle increased. Also kinetics of drug release was studied using mathematical models of zero-order, first-order, Higuchi, Korsmeyer-Peppas and Hixson-Crowell, where Higuchi and Korsmeyer-Peppas models best defined the kinetics of drug release.

Hydrogel microfibers with inhomogenous structure can achieve some complex motions such as bending, folding and twisting. So it can be applied to soft actuators, soft robots and micropumps. In this paper, continuous bilayer hydrogel fibers in which one layer is calcium alginate hydrogel and the other is linear poly(N-isopropylacrylamide) (PNIPAM)/calcium alginate/graphene oxide (GO) semi-interpenetrating hydrogel were prepared based on microfluidic spinning method. The results show that the bilayer hydrogel fibers have particular porous internal structures of semi-IPN hydrogels and the pore size becomes smaller with the increase of GO content. Besides, the bilayer hydrogel fibers can bend response to the temperature and near-infrared (NIR) light. The diameter of the hydrogel fibers can be tuned by changing the flow rate of spinning fluid and the take-up velocity of winding device. Graphical Abstract

This study facilitates the synthesis process of a novel graft copolymer (flocculant) using carboxymethyl cellulose, acrylonitrile and N-vinyl formamide as raw materials. The carboxymethyl cellulose graft polyamidine (CMC-g-PAMD) can be used as new flocculant to replace the traditional polyacrylamide flocculant, which manifested its excellent flocculation and degradation efficiency. A five-membered cyclic copolymer was prepared by the graft copolymerization, and the synthesized flocculants were characterized by EA, TG-DTG, FT-IR, SEM and NMR, confirming the successful synthesis of the desired copolymers. The operation conditions for copolymerization were experimentally investigated, and the results indicated that the optimal initiator dosage, copolymerization temperature, amidinization temperature, acidification time and flocculant dosage were 4 g/L, 50°C, 90°C, 3 h and 60 mg/L, respectively. Compared with the traditional polyacrylamide flocculant, the CMC-g-PAMD presented an outstanding flocculation ability of 96.1% under its optimal operation conditions, which showed an enormous potential in the application of coalmine waste-water treatment. Graphical Abstract

A DOPO (9,10-dihydro-9-oxa-10-phosphaphen-anthrene-10-oxide)-based halogen-free flame retardant (ODOPM-CYC) was synthesized and incorporated in rigid polyurethane foam (RPUF). The structure of ODOPM-CYC was characterized by Fourier transform infrared spectra (FTIR), 1 H NMR and 31 P NMR. The effects of ODOPM-CYC on the flame resistance, mechanical performances, thermal properties and cell structure of RPUF were also investigated. The results showed that the incorporation of ODOPM-CYC strikingly enhanced flame retardant properties of RPUF. The flame retarded RPUF acquired a limiting oxygen index (LOI) value of 26% and achieved UL-94 V-0 rating with the phosphorus content of 3 wt%. The smoke production rate (SPR) also showed an obvious decrease and total smoke release (TSR) was 39.8% lower than that of neat RPUF. Besides, the results demonstrated that the incorporation of ODOPM-CYC provided RPUF better thermal stability but did not show any obvious influence on its thermal conductivity. Graphical Abstract

A series of chitosan and Laponite based nano-composite adsorbents, which showed an excellent performance for fast and efficient removal of Cd(II), methylene blue (MB) and Congo red (CR) from aqueous solution, were prepared. In the adsorbent, with the increase of Laponite component, the surface area increased from 44.69 m 2 g -1 to 64.58 m 2 g -1 . As a result, the adsorption rates were enhanced by increasing Laponite component. The adsorption capacities for Cd(II) and MB increased with increasing Laponite component due the cationic characteristic of two pollutants, and the opposite result was found for the removal of CR. The impacts of some factors, e.g. solution pH, temperature, pollutant concentration and salt, on the adsorption capacity were investigated. Additionally, this adsorbent could be effectively regenerated by dilute HCl solution after the adsorption of Cd(II), and the mixture of methanol and acetic acid was a suitable eluent after the adsorption of two dyes. Graphical Abstract

Cerium (Ce)-ferric (Fe) complex oxides were prepared via a citric acid sol-gel process, and used as thermal oxidative stabilizers for silicone rubber (SR). The oxides were characterized by X-ray diffraction and Raman spectroscopy. The Ce/Fe molar ratio in Ce-Fe complex oxides significantly influenced the thermal oxidative stability of SR. After aging at 300°C for 24 h, SR filled with 4 phr Ce-Fe complex oxide with a Ce/(Ce+Fe) molar ratio of 0.8 (CeFeO-0.8) exhibited excellent thermal oxidative stability, retaining 56.8% and 54.3% of its original tensile strength and elongation at break, respectively. Some Ce 3+ and Fe 2+ ions were detected in aged SR composites. Ce 3+ /Ce 4+ and Fe 2+ /Fe 3+ molar ratios in SR/CeFeO-0.8 were less than that in SR/CeO 2 and SR/Fe 2 O 3 composites, respectively, as detected by X-ray photoelectron spectroscopy. It implies rapid re-oxidations of Fe 2+ and Ce 3+ occurred in SR/CeFeO-0.8, enhancing the capacity of CeFeO-0.8 to capture radicals during thermal aging. Graphical Abstract

Wound infection is a significant burden on public health. Most present antibacterial agents are typically toxic and devoid of long-term durability. We reported an antimicrobial microcapsule with Chinese nutgall (CN) encapsulated, which was a plant-derived extraction. It is biocompatible and has been used in traditional medicine systems. Sodium alginate (SA) and chitosan worked as shells. The promise of the design is to adopt biocompatible natural polymers and electrostatic attractive chitosan and SA form stable shells to keep long-term release of CN. The results exhibited microcapsules with integrated performance of biocompatibility, long-term durability (inhibition rate of 98.99% against S. aureus after 12 h and 100% after 12 h, 99.61% against E. coli after 6 h and 100% after 12 h), high antibacterial efficacy (with S. aureus inhibition zones of 7.67 mm and E. coli inhibition zones of 5.27 mm) and ease of storage (-20°C for more than 60 h). Their successful fabrication may provide new insights into application of traditional cotton gauze in a sustainable and multifunctional form.

Fully water-blown polyisocyanurate-polyurethane (PIR-PUR) foams with improved mechanical properties have been prepared using aqueous solutions of metal-ammonia complex, Cu(Am) or Zn(Am), as gelling/blowing catalysts and potassium octoate (KOct) solution in diethylene glycol as a trimerization catalyst. Two catalyst mixtures, Cu(Am)+KOct and Zn(Am)+KOct, were obtained as homogeneous aqueous solutions. In comparison to commercial catalyst system, DMCHA+KOct (DMCHA = N,N-dimethylcyclohexylamine), Cu(Am) and Zn(Am) could be miscible with KOct solution and water easier than DMCHA. This miscibility improvement led Cu(Am)+KOct and Zn(Am)+KOct to show faster catalytic reactivity in PIR-PUR foam reactions than DMCHA+KOct. All obtained PIR-PUR foams showed self-extinguishing properties and achieved HF1 materials. However, PIR-PUR foams prepared from Cu(Am)+KOct and Zn(Am)+KOct at NCO:OH ratio of 2:1 had suitable density for industrial applications and showed higher compressive strength than that prepared from DMCHA+KOct. These foams have high potential to apply as insulations for constructions, core laminates in wall panel or storage tanks.

Acrylpimaric acid ethylene glycol acrylate was used as the cross-linking agent to prepare rosin-based polymer microspheres through membrane emulsification–microsuspension polymerization. The prepared microspheres were used as the stationary phase in high-performance liquid chromatography for the separation of polycyclic aromatic hydrocarbons (PAHs) and two analogues of alkaloids. Five PAHs (benzene, naphthalene, fluorene, pyrene, and benzo(e)pyrene) were well separated in the rosin-based polymer column with the resolution (Rs) of 6.088 ± 0.006, 5.759 ± 0.017, 7.019 ± 0.020, and 8.584 ± 0.063. A linear relationship was observed for the carbon numbers of PAHs and lnK as obtained with the equation of ln k = 0.22 n c – 2.45, R 2 = 0.996 . The rosin-based polymer columns were also employed to separate theophylline–caffeine and camptothecin–10-hydroxy-camptothecin, and the good results were obtained with the Rs of 4.617 ± 0.005 and 2.245 ± 0.049, respectively. Graphical Abstract

It is well known that polylactide (PLA) is difficult to foam due to its low melt strength. Thus, many ways were described in the literature to enhance the foamability. However, the melt strength was actually determined only in a limited number of publications. In this study, the addition of chemical modifiers was used to change the rheological behavior of PLA and thereby improve its foamability in foam extrusion process. For the first time the use of dicumyl peroxide modified PLA in foam extrusion is described. Both modifications lead to a distinct increase in melt strength. Here, the highest increase was shown for the PLA modified with dicumyl peroxide. Furthermore, strain hardening was observed for PLA modified with the peroxide. Low density foams were achieved for neat and modified PLA in foam extrusion. Neat PLA showed a density of 45 kg/m 3 , while the peroxide modified PLA showed the highest expansion with a density reduction down to 32 kg/m 3 . Both modifications result in a more uniform cell structure and an improved compression strength. Here, the foamed, peroxide modified PLA showed outstanding performance compared to neat PLA foam with twice the compression strength (151 Pa) even at a 30% lower density.

The present work focuses on fabricating a flexible and thermally conductive PI composite film. The PI composite film was obtained by blending hexagonal boron nitride (h-BN) combined with ethyl cellulose and 2,2’-Bis(trifluoromethyl) benzidine (TFMB) functionalized GO (TFMB- GO) in polyimide (PI). The ethyl cellulose successfully formed the thermal conduction network by promoting the dispersion of h-BN in PI matrix. Thus, the thermal conductivity of the PI composite film with ethyl cellulose could be twice than PI film without ethyl cellulose. Besides, the PI composite film containing 30 wt% of h-BN could still exhibit excellent flexibility. Moreover, the combination of TFMB-GO could increase the tensile strength of the PI composite film by up to 80%. Overall, we provided a novel idea for the preparation of flexible substrate materials with efficient heat dissipation which was convenient and possible to apply widely in the industrial production.

In this study, ionic liquids (IL) containing carboxyl and different alkyl chains were fabricated and used to dope polyaniline (PANI). The results revealed that IL@PANI composites could be facilely obtained via template-free polymerization of aniline using ammonium persulfate as the oxidant. The as-prepared IL@PANI composites were measured by FT-IR, XPS, and SEM. Electrochemical performances of IL@PANI nanocomposites were investigated by cyclic voltammetry and galvanostatic charge/discharge. The results indicate that the alkyl chains of ILs have an important influence on the morphology and capacitance performance of IL@PANI electrode materials. With the shorter alkyl group in ILs, IL@PANI materials presented higher specific capacitance. Especially, 1-vinyl-3-carboxymethyl-imidazolium chloride ([VCMIm]Cl)@PANI composite presented the highest specific capacitance. Cycling performance measurement demonstrated that 82% capacitance retention could be achieved after 1000 cycles in 0.5 M H 2 SO 4 aqueous solution. Therefore, our strategy provides a new technique for PANI nanocomposites with tunable morphology and high performance.

In this paper, γ-valerolactone (GVL), a bio-based polar solvent, was applied as green solvent for iron(III)-catalyzed AGET ATRP without any external ligand. GVL is a fully degradable, non-toxic green solvent and has complex ability to iron halide complexes through –OCO- group. GVL as the solvent and the ligand for AGET ATRP of MMA in a controlled manner, as proved by kinetic study, the low PDI values and the increase in polymer molecular weight versus monomer conversion. Chain re-initiation experiments and 1 HNMR characterization were conducted to further confirm the living feature. Graphical Abstract

This study deals with the subject of optimizing the melt electrospinning process of polypropylene with the aim of producing nanoscale fibers. A feasibility study with two polypropylene types and different additives to adapt the material composition is performed. The polypropylene types are of different molar masses to adapt the viscosity to the process. The used additives, sodium stearate and Irgastat ® P 16, have a positive effect on the electrical conductivity of the polymer melt. In addition, process parameter optimization is done by varying the climate chamber temperature, using different collector voltages and varying the nozzle-collector distance. A strong influence of the climate chamber temperature has been proven and leads to a desired temperature of 100°C. The fiber diameter is dependent on process parameters, material melt viscosity and electrical conductivity. With optimized process and material parameters, the fiber diameter could be minimized to a median value of 210 nm.

The increasing applications of poly-ether-ether-ketone (PEEK) in the industry makes this polymer appealing for the development of a new industry focused on its production. PEEK displays remarkable mechanical properties that are not commonly found in polymeric materials, and its biocompatibility becomes attractive for the manufacture of prosthesis, stents and many other medical apparatuses. In addition, the new technique of Additive Manufacturing (AM) enables the printing of highly complex geometries with low weight, aiming the automotive and aeronautic industries as well. Despite not being relatively new, there are not many enterprises producing PEEK in the world, especially in the South American market. This raises a question regarding the size of the PEEK market in this region and the expected demand for the upcoming years. Therefore, this paper aims to analyze and predict the demand of PEEK for the Mercosur and Brazil markets, verifying the feasibility of the creation of a specialized industry in the region.

Expandable Polystyrene (EPS) is one of the most commonly used material, when it comes to protect thermal sensitive goods, since the thermal conductivity of EPS is very low. The mechanical properties in terms of long-term compression or quasi-static compression are also quite well known. But when the material is loaded with higher amplitudes over a long period of time, not much is known yet about long-term mechanical behavior. For example, as a packaging material, EPS exhibits complex loading situation ranging from small to high amplitudes over a long period of time, when e.g. it is transported in a truck, a ship or in a car. In order to characterize the mechanical behavior under such large amplitude loading, the dynamic fatigue needs to be recorded and evaluated. In this paper, the principles of the hysteresis measurements evaluation are applied on EPS for the first time to unveil long-term mechanical properties in compression. Results show, that after increasing the dynamic load level to a critical level of over 100 kPa, the mechanical behavior, in terms of compression rate, of EPS changes from a linear to a kind of exponential mode.

The application of polydicyclopentadiene (polyDCPD) as a high-performance thermosetting resin is often hindered by the simplicity and limitation of the polymer structure, making it unlikely to improve their thermal and dynamic mechanical properties by further optimizing the polymerization conditions. In this study, we developed a copolymer system which consisted of dicyclo-pentadienes and various designed monomers as excellent curing agents. The incorporated monomers bearing different stiffness and rigidity contain two active functional groups at the end of the structures and are capable of reinforcing original polyDCPD. The incorporated monomers notably enhanced the thermal and dynamic mechanical properties of polyDCPD. Besides that, the relationship between the stiffness of the monomer and the thermal and dynamic mechanical properties of polyDCPD was evaluated in detailed. Because of the simplicity and adjustability of copolymerization approach, optimal conditions of the copolymers with best property-reinforcing capability were systemically identified. The optimal materials displayed desired thermal and dynamic mechanical property and markedly outperformed the original polyDCPD.

Polyacrylate resin composite materials with the mineral exhibit super water absorbency and good degradation ability. In this work, expanded perlite and sodium polyacrylate resin composite materials have been prepared with ceric ammonium nitrate (CAN), N,N’-methylene bisacrylamide (MBA), tapioca starch, and expanded perlite. Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (SEM) are used to characterize the bonds absorption peaks and morphologies. The results suggest that the expanded perlite can graft on sodium polyacrylate resin, and the optimal distilled water and 0.9% NaCl absorbency are 1079 and 253 g/g when the expanded perlite content is 8 wt%, respectively. The swelling water model of the composite materials is firstly simulated to be Voigt-based model. In addition, the composite materials absorbency that is influenced by special characteristics of the expanded perlite has been shown.

A simplified procedure has been developed to optimize the molding processes of thermosetting resins. The proposed methodology involves the classical finite element commercial package (NISA II v. 17). Here, the theoretical background and numerical implementation of the procedure are described. Various design variables that can describe the RIM are discussed. The solved example represents the influence of the heating regime on the curing process. The results are compared with the results obtained with the use of full analysis conducted with the aid of the finite volume analysis (filling and curing stages). They demonstrate the evident advantages of using the simplified optimization approach.

Stimuli responsive helical polymers have attracted wide attention and many polymers responsive to the external stimuli have been synthesized. But, only a few examples have been reported regarding the redox-induced helicity inversion helical polymers. The polyisocyanide including thioether pendant (poly-MBTIP) was synthesized by polymerization of methyl (R)-3-(benzylthio)-2-isocyanopropanoate (MBTIP) monomer using NiCl 2 ·6H 2 O as catalytic agent in dry DCM. The chiroptical and oxidation properties of the poly-MBTIP are investigated. The poly-MBTIPs exhibit intense specific optical rotations and Cotton effects compared to the monomer, strongly suggesting a helical conformation of the polymer backbone. Additionally, the thioether pendant of poly-MBTIP backbone was oxidized to sulfoxide group by H 2 O 2 . Interestingly, the specific optical rotations and Cotton effects of poly-MBTIP oxidized are reversed, probably suggesting a helical conformation inversion. Graphical Abstract

Over the past two decades, biodegradable polymers (BPs) have been widely used in biomedical applications such as drug carrier, gene delivery, tissue engineering, diagnosis, medical devices, and antibacterial/antifouling biomaterials. This can be attributed to numerous factors such as chemical, mechanical and physiochemical properties of BPs, their improved processibility, functionality and sensitivity towards stimuli. The present review intended to highlight main results of research on advances and improvements in terms of synthesis, physical properties, stimuli response, and/or applicability of biodegradable plastics (BPs) during last two decades, and its biomedical applications. Recent literature relevant to this study has been cited and their developing trends and challenges of BPs have also been discussed.

In this study, carbon fibre powder has been used as reinforcement to enhance the electrical conductivity of bio-based rigid polyurethane foam. Effect of carbon fibre incorporation on the mechanical, thermal and flame retardant properties has also been investigated. Results concluded that the foams with 8% carbon fibre concentration showed up to 288% increase in compressive strength. Furthermore, up to 28% decrease in the peak of heat release rate (PHRR) was observed on the incorporation of carbon fibre powder. Additionally, the rate of smoke production was also found decreased for carbon fibre reinforced foams. Foams with 8% and 10% carbon fibre concentration show conductivity of 1.9 × 10 -4 and 7.1 × 10 -4 S/m, respectively. So, carbon fibre powder may be used as a potential filler to enhance the electrical conductivity of rigid foams without compromising the other properties. Graphical Abstract

It is found that forced (reactive) blending of polystyrene (PS) with polymethylmethacrylate (PMMA) involves the covalent binding of heterogeneous macromolecules to afford the paired polymers. For this purpose, the “anchor” N-H unsubstituted tetrazole or oxirane functional groups are preliminarily introduced in the structure of both polymers in a small amount that leads to a covalent binding of the heterogeneous macromolecules. The reaction between the modified PS and PMMA is carried out in dimethylformamide (DMF), toluene and dichloroethane (DCE) at a high total concentration of polymers (10-20 g dL -1 ). The process is accompanied by gel-formation to deliver cross-linked paired polymers It is established that the highest rate of the paired polymer is attained in the DCE medium, while the lowest rate is observed in DMF. For paired polymers synthesized in DMF, two glass transition temperatures ( T g ) of 92°C and 104°C correspond to the original PS and PMMA, respectively. The products of forced blending of PS and PMMA in toluene have one averaged T g value (99°C), whereas those obtained in DCE show no pronounced glass transition region at 90 ÷ 115°C. In toluene or DCE, the paired polymers are formed, which represent single-phase systems having one glass transition region.

The effect of coupling agent on the morphological characteristics of natural rubber/silica composite foams with various silica contents was studied. Bis 3-triet-hoxysilylpropyl tetrasulfide (TESPT) was used as coupling agent in this system. It could make a chemical bond with the silica particles. By increasing the silica content, cell size of foams was reduced more that 50% and foam density was increased up to 40%. However, compatibilized composites demonstrated about 20% lower foam density and higher cell size. In this case, strong adhesion between the components prevented gas from escaping out. While, in the foams excluded coupling agent the weak adhesion between particles and rubber created an escape path for gas from the interface of components. So, lower cell size and higher density were achieved.

Dicyclopentadiene (DCPD) resin has gained popularity owing to its fast curing time and ease of processing with a low viscosity in the monomer state. In the present study, the impact and shear properties of a carbon fiber (CF)/p-DCPD composite were investigated. The CF/p-DCPD composite was manufactured by vacuum-assisted resin transfer molding with CF as the reinforcement and p-DCPD as the resin with a maximum fiber volume fraction of 55 weight percent. Impact and shear properties of the CF/p-DCPD composite were evaluated and compared with those of a CF/Epoxy composite. The maximum shear stress and modulus of the CF/p-DCPD composite were lower than that of the CF/Epoxy composite. However, the CF/p-DCPD composite had higher toughness than that of the CF/Epoxy composite; this indicates that it is tougher and exhibits a more ductile load-displacement response with a lower modulus and larger failure deformation. The impact strength of the CF/p-DCPD composite was about three time that of the CF/Epoxy composite. The higher impact strength of the CF/p-DCPD composite is attributed to the resin characteristics: epoxy resin has a more brittle behavior, and hence, higher energy is required for crack propagation due to fracture.

Effects of the type, chemical structure and NCO/OH of resins on wet adhesion and salt spray resistance of two component waterborne polyurethane coating were studied in this paper. The content of functional groups in resins and films were analysed by areas of their FT-IR absorption peak to study the relationship with anticorrosive performance of coatings. Coatings based on resins with more -OH tend to have stronger wet adhesion and salt spray resistance because resins with more -OH have more possibilities to react with -NCO to form a compact film with a higher crosslinking degree. The wet adhesion of coatings after 8 h of immersion deteriorated from level 1 to level 5 with the increase of NCO/OH due to the decrease of -OH in coatings to link with substrates. And excess -NCO tend to react with H 2 O to generate CO 2 to form cracked physical bubbles, which would weaken the wet adhesion.

Biodegradable polymer electrolyte systems are the most sought over option for cheap and energy efficient storage devices. Present paper discusses the results of potato starch + MgCl 2 system which satisfy the technical and economic criteria to become a potential candidate for future electrolyte systems. The developed system has high ionic conductivity (~3.43 × 10 -2 S/cm), low relaxation time (75 μs) and wide electrochemical stability window (ESW ~4.6 V). The phase angle approaches -79° and maintains its value for 10 Hz to 1 kHz frequency range. The prepared material is a free standing film which can be bended and twisted up to 90°, which makes it suitable for flexible electrochemical device fabrication. The equivalent series resistance (ESR) is quite low (3.41 Ω) and self-resonance frequency below which energy can be efficiently stored is approximately 0.1 MHz. Hence the present study reports an economical, easy to handle and environment friendly electrolyte suitable for electrochemical device fabrication.

2.5D quartz fiber reinforced boron phenolic composites with different curing degrees were prepared by different curing temperatures and curing times. The effects of curing degree on the flexural strength and thermal properties of the composites were investigated by mechanical properties test, scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The results show that the flexural strength increases to the increase in the degree of cure, but the rate of increase is non-linear. When the degree of cure is higher than 90%, the flexural strength of the composite is more than 300 MPa and the bending failure mechanism of the composite is analyzed by SEM. The TG test showed that the degree of cure had little effect on the residual weight of the composite at 1000°C, but had a greater effect on the temperature of the previous weight loss.

An aqueous silica (SiO 2 ) dispersion was prepared by using silica as ceramic particles, polyvinyl alcohol (PVA) as a binder and deionized water as a dispersion medium. A SiO 2 ceramic layer was applied to the surface of the polypropylene (PP) separator by dip coating. The separators before and after modification were characterized by XRD, SEM, DTA, lyophilic performance test, contact angle test and heat resistance test. The separators were assembled into lithium-ion batteries for electrochemical performance test. The results show that after the successful introduction of SiO 2 /PVA coating on the surface of PP separator, the lyophilic and heat resistance and electrochemical performance of PP separator have been improved significantly. The battery rate performance and cycle performance are significantly improved. Especially the capacity retention rate of the original separator was only 75.79% at 100 charge-discharge times, and that of the modified separator was as high as 87.18%.

Fermentation of hyaluronan (HA) by Streptococcus zooepidemicus was carried out in a 10-L fermentor. When the medium pH was controlled at 7.0 and the temperature was maintained at 38°C for 12 h followed by 35°C for 8 h, the yield of HA was 4.83 g/L with a molecular weight of 1,890 kDa. After the cells were removed by centrifugation from the fermentation broth, HA was slowly degraded to low molecular weight HA by hyaluronidase at a suitable temperature without a decrease in HA concentration. If the time and temperature for enzymatic degradation were controlled, the desired low molecular weight HA could be obtained by in situ degradation in the fermentation broth. The method does not require the addition of exogenous hyaluronidase, and is a simple way to produce low molecular weight HA.

Ground tire rubber (GTR) with crosslinked structure shows hardly any plasticity and processability, giving rise to its relatively poor properties. The thermal-mechanical shearing devulcanization can effectively break the three-dimension crosslinked network structure and restore a certain extent of plasticity and processability. In this work, reclaimed rubber (RR) was obtained by thermal-mechanical shearing devulcanization as a potential filler for natural rubber. The vulcanization process, mechanical properties, microstructure of RR/natural rubber (NR) compounds composites were investigated. It was found that the NR vulcanizates containing 30 phr of RR as filler showed the higher tensile strength and elongation at break. Microstructural characterization analysis on a sample containing 30 phr of RR revealed the existence of strong interactions between the natural rubber matrix and RR, suggesting that RR and NR appeared to be well-matched, undergoing simultaneous curing and forming a continuous phase.

In order to improve the toughness of epoxy resin for grouting material, the flexible hexamethylene diisocyanate (HDI) was utilized to manufacture a new kind of epoxy resin with high toughness via co-polymerization method. In the procedure of preparing bisphenol A epoxy resin, before the reaction between bisphenol A (BPA) and epichlorohydrin (ECH), HDI was introduced to react with BPA for embedding flexible segments into the chain of epoxy resin, then modified epoxy resin (HDI/EP) was manufactured. The mechanical properties, especially the toughness of the HDI/EP, are significantly increased – the fracture elongation is up to 124%. In addition, the compressed specimens can fully recover to their original shape in a few minutes. Thermal performance and corrosion resistance of the HDI/EP specimen were also investigated, which showed that the specimen can be used under 258°C, and can remain stable in H 2 SO 4 , NaOH and NaCl solutions with 10 wt% for 100 h, respectively. The present work provides a convenient avenue pathway to prepare an epoxy resin with high toughness, which may be used in many technologies.

Herein, high density polyethylene (HDPE) matrix was applied as the polymer matrix for its excellent overall performance and low price. In the study, antioxidants (0.5 phr) and ultraviolet absorber (1 phr) were added into the polymer matrix (100 phr) to investigate their influence on UV resistance, respectively. The macroscopic properties and microstructure changes of the samples were both investigated through the characterizations of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), mechanical properties and thermogravimetric analysis (TGA). This work also conceived the three methods of capturing free radicals generated by photoaging, decomposing peroxides generated by photoaging, and absorbing ultraviolet light to achieve anti-aging effects. The results showed that the UV absorber improves the UV resistance of the material better than the antioxidant. After irradiation for 600 h under the aging condition of 0.51 w/m 2 @λ = 340 nm, the samples added with UV absorber also still maintain their mechanical properties at a high level. For comparison, the samples added with antioxidants presents poor mechanical properties only after irradiation for 200 h. Besides, the crystallinity of HDPE and HDPE added with antioxidant significantly increased after irradiation, but the crystallinity of HDPE introduced with UV absorber presents slight changes before and after irradiation. Meanwhile, all the irradiated samples also maintained the original excellent thermal stability. According to the obtained results, the aging mechanism was also analyzed.

This paper presents the synthesis of two aminosilane-based external donors for the Ziegler-Natta catalysis: di(piperidyl) dimethoxysilane (DPPDMS) and dipyrrolyldimethoxysilane (DPRDMS). We compared the electron donation by these two compounds in the MgCl 2 - supported Ziegler-Natta catalysis of the polymerization of hexene-1 into a polyhexene-1 (PHe) elastomer with that of the common donor cyclohexylmethyldimethoxysilane (CHMMS). The catalytic activity of the system and isotacticity of the polymer (PHe) product improved significantly because of the considerable steric hindrance and strong electronic effects of these aminosilane-based external donors. The effects of different external donors on the catalytic efficiency, polymer isotacticity, molecular weight and molecular weight distribution of the PHe products were investigated. Under the best reaction conditions, the catalyst activity, polymer molecular weight, and glass-transition temperature were determined as 899 g/g Cat·h -1 , MW = 252,300 g/mol, and -41.39°C, respectively. The PHe was characterized by FTIR and NMR. This report also describes blending of PHe and low density polyethylene that leads to a significant increase in the impact strength and elongation at breaks.

Microencapsulated phase change materials (MicroPCMs) were fabricated using n -octadecane as PCM and melamine-formaldehyde as shell via in situ polymerization. They were coated with polypyrrole (PPy) to fabricate conductive microcapsules. The structure, morphology, thermal properties and the electrical conductivity of the microcapsules were characterized using the scanning electron microscope (SEM), the Fourier transformed infrared spectroscopy (FTIR), the thermo gravimetric analysis (TGA), the differential scanning calorimetry (DSC) and the standard four-probe method. The results show that, n -octadecane is well encapsulated in rough and compact spherical composites. The melting and freezing the composites latent heats are 90.2 and 92.0 J/g, respectively, while the mass percentage of the n -octadecane in the composites is 49.7%. The melting and crystallizing peak temperature of PPy/MicroPCMs is 24.6°C and 17.9°C, respectively. The addition of PPy improves the thermal stability of the composites. The conductivity of the PPy/MicroP-CMs increases from 0.1 S‧cm –1 to 0.33 S‧cm –1 as the PPy concentration increases from 3 to 10 wt%.

Under harsh conditions, the desorption of polyampholytes from bentonite (Bent) can affect the performance of drilling fluids. To study the desorption of polyampholyte from bentonite, partially hydrolyzed copolymers of acrylamide and diallyl dimethyl ammonium chloride (HPAD), containing carboxyl groups, quaternary ammonium groups and amide groups was synthesized via free radical copolymerization followed by hydrolyzation. The molecular structure of HPAD was characterized by 1 H NMR and 13 C NMR. The adsorption equilibrium of HPAD on Bent in the presence of 10 wt% NaCl was 106 mg·g –1 . The adsorption-desorption behavior of HPAD on Bent was studied using a high pressure and high temperature (HPHT) filtration apparatus, to obtain the filtrate liquid and filter cakes. The content of HPAD in the filtration and the filter cakes was determined via UV and element analysis, respectively. As the temperature increased, the desorption of HPAD from Bent accelerated owing to molecular thermal motion and thermal degradation of the adsorptive groups. Notably, the decomposition rate of the amide group was more than twice that of the quaternary ammonium group. The critical temperature for HPAD desorption was 135°C, as the decomposition of the adsorptive groups became predominant over intensified molecular thermal motion at high temperatures.

Polyurethane reactive hot-melt adhesives (PURHs) are frequently employed in industries; however, there is still a need to develop more sustainable and versatile methodologies to expand the functions and fabrication of these important materials. Renewable feedstock can give PURHs with new functions, and reduce environmental impact. This study focuses on synthesizing PURHs using polyols derived from biomass (plants) and greenhouse gas (CO 2 ) resources. These PURHs were characterized by multiple techniques, including solid-state 13 C nuclear magnetic resonance (NMR), a dynamic mechanical analysis (DMA), single-lap adhesive joints strength of stainless steel, and hydrolytic ageing. The PURH film based on biomass poly(tetramethylene ether) glycol (bio-PTMEG) exhibited better water vapor permeability, tensile strength, and adhesive joints properties than PURHs based on cashew nutshell liquid (CNSL) polyester diol and poly(propylene carbonate)-poly(propylene glycol) (PPC-PPG) copolymer diol. The polyols blend of bio-PTMEG with biomass and CO 2 based polycarbonate diols respectively provided PURHs films excellent hydrolysis resistance and adhesive strength on single-lap adhesively bonded stainless steel specimens. The work herein demonstrates that various renewable polyols can be employed in a sustainable fashion to optimize the structures and properties of PURHs for important applications.

In order to improve the compatibility of flame retardant and epoxy resin, a phosphorus nitrogen flame retardant curing agent poly(p-xylylenediamine spirocyclic pentaerythritol bisphosphonate) (PPXSPB) was synthesized. FTIR, 1 HNMR, and mass spectroscopy were used to identify the chemical structure of PPXSPB. Epoxy resin (E-44) and PPXSPB as the raw material, a series of thermosetting systems were prepared. The effects of PPXSPB on flame retardancy, water resistance, thermal degradation behavior, mechanical properties and the adhesive strength of EP/PPXSPB thermosets were investigated. The results show that with the increase of phosphorus content, the oxygen index and carbon residue of the system both increased significantly, and the heat release rate gradually decreased, which is of great significance in delaying the occurrence of fire. When the phosphorus content is 3.24% in EP/PPXSPB thermosets, EP-2 can successfully pass the UL94 V-0 flammability rating, the LOI value of EP-2 can reach 31.4%, the impact strength and tensile strength was 6.58 kJ/m 2 and 47.10 MPa respectively, and the adhesive strength was 13.79 MPa, the system presents a good overall performance.

In order to match the fabrication process of flexible Copper-Indium-Gallium-Selenide (CIGS) solar cell, a series of polyimides (PIs) with high initial decomposition temperatures (Td) were prepared from 6,4′-diamino-2′-trifluoromethyl-2-phenylbenzimidazole (DATFPBI), p-phenylenediamine (p-PPD), and S-type biphenyl dianhydride (s-BPDA) using a sequential copolymerization, casting, and thermal imidization process. The physical properties of the PIs were found to be effectively modified by adjusting both the ratio of the rigid momomers and the thermal imidization process. With the introduction of DATFPBI, the polymers showed significant improvements in thermal stability, thermal expansion, moisture absorption and mechanical properties. PIPBId, one of the synthesized PI film, exhibited an excellent comprehensive performance: a glass transition temperature of 368°C, a tensile modulus of 6.8 GPa, a linar coefficient thermal expansion (CTE) of 16.8 ppm/K, and a moisture absorption of 1.42%. Furthermore, Td of this thin film was up to 524°C,which indicated that the PIPBId film is a competitive candidate as the flexible substrate for CIGS, Copper-Zinc-Tin-Sulphide (CZTS) solar cell and flexible printed circuit boards (FPCB) where high process temperature is necessary.

Expanded vermiculite (EV) was introduced into rigid polyurethane (RPU) foam. The incorporation of 10 wt% EV into RPU foam increases the compressive strength and the flexural strength by 82% and by 115%, respectively compared with untreated RPU foam. The LOI of RPU foam containing 20 wt% EV is only 19.5%. To further improve the flame retardancy of RPU/EV composite foam, melamine phenylphosphate (MPP) was synthesized and introduced into the RPU/EV composite foam. The RPU/EV composite foam with 15% MPP (sample RPU/EV/MPP15) has a LOI of 27.5% and a V0 rating in the vertical UL-94 test. The PHRR and THR of sample RPU/EV/MPP15 decrease by 39% and 24%, respectively, compared with the ones of untreated RPU/EV composite foam. The compressive strength and flexural strength of RPU/EV/MPP composite foam gradually decrease with the increase in the amount of MPP. TGA results indicated that the addition of MPP further increase the residue char of the RPU/EV composite foam.

A novel shale inhibitor was synthesized by free radical copolymerization in aqueous solution, using acrylic acid (AA), acrylamide (AM), maleic anhydride (MA) KH-570 as reaction monomers and potassium persulfate as initiator. The structure of the copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR). Thermogravimetric analysis (TGA) showed that the thermal decomposition temperature of the copolymer was higher than 226°C, which indicated that the copolymer had good high temperature resistance. At the same time, the inhibition performance of the copolymer was further evaluated by linear expansion, immersion test and rolling recovery. The experimental results show that the inhibition performance of organosilicon polymer is obviously better than that of potassium chloride (KCl) and potassium polyacrylate (KPAM), and it can be used as an inhibitor in shale gas drilling.

In this paper, a millimeter-sized temporary plugging agent particles based on polyacrylamide were synthesized by combining microfluidics technology with consolidation mechanism of suspension polymerization, which using W/O emulsion template and with droplet as micro-reaction vessel. The effect of various variables on the gel particle properties was studied so as to determine the best proportion and optimize the preparation process. Fourier transform infrared (FTIR) spectroscopy, Digital imaging and SEM were used to characterize the composition and morphology of the PAM gel particle. The results indicated that the obtained PAM gel particle has regular shape and good transparency. And it is concluded that when the molar ratio of acrylic acid (AA) and acrylamie (AM) monomers is 5:5, w(K 2 S 2 O 8 ) = 0.8%, w(Al(NO 3 ) 3 ) = 1.0%, neutralization degree was 60%, the prepared PAM gel particles has the best performance. The preparation process is simple while the cost is low, so it could be used as a promising temporary plugging agent in future.

Three kinds of acrylamide copolymers were synthesized in this paper, acrylamide (AM) homopolymer, acrylamide/acrylic acid (AA) copolymer and acrylamide/2-acrylamide-2-methylpropanesulfonic acid (AMPS) copolymer by free radical polymerization. The aggregation behaviours of these polymers in salts water solution were studied. The molecular chains of homopolymer were stretched in salt water solutions, since it did not undergo hydrolysis and there were no charges in the backbone and side chains. Therefore, the conformation of homopolymer was hard to be attacked by salt ions. However, the copolymers synthesized from these monomers had large number of anionic groups. These anions were easily attracted by cations from salt solutions forming ionic bonds, which led to changes in molecular conformation. The viscosity of copolymer decreased since the molecular chains were crimped. The viscosity of copolymer decreased distinctly according to the temperature of different salt solutions, as temperature had great impact on the viscosity of copolymer. The interaction mechanism of polymers exhibited great difference in salts solutions, comparing to temperature. High temperature reduced the entanglement between molecular chains, whereas salt ions neutralized the negative charges on the molecular chains causing curling of molecular chains.

The asymmetric star polymers are studied by coarse grain simulations. Each polymer chain is represented by number of consecutive soft blobs and additional uncrossability constraints are added to prevent chain crossings. In this work two types of asymmetric star polymers with different backbone lengths are structured. Their dynamical properties are discussed by comparisons with corresponding linear chains, the one covers chain length along with the asymmetric arm through the branch point to one of the symmetric arm, or the backbone chain between two symmetric arm ends, or the largest linear possesses the same molecular weight of the entire star. To reveal the influence of the asymmetric arm length on their relaxation decay times, the autocorrelation function of the vectors from each branching point to corresponding asymmetric arm end are calculated, results are compared with the symmetric star having the same backbone chain.

In order to reduce the melt-blowing fiber diameter, an improved slot die with internal stabilizers was designed. The air-flow field of the improved die was measured by a hot wire anemometer. Furthermore, utilizing computational fluid dynamics software, the air flow field from the improved slot die was studied and the work was validated with the laboratory measurement data. The experimental results and numerical simulation data indicate below the die surface, the internal stabilizers play an important role in the velocity distribution of the flow field. Firstly, the improved slot die can increase the velocity and the temperature near the centerline of the flow field and reduce the maximum value of turbulent kinetic energy, compared to the common die. Secondly, the end face of the slot hole has a certain influence on the surrounding flow field and the central area exhibits two-dimensional flow field distribution.