Band 36, Heft 5

A low cost composite material was prepared by using waste newspaper and polyester resin. The waste newspaper used in the study was characterized by chemical and X-ray diffraction (XRD) methods, and tensile strength was measured. Waste newspaper contains holocellulose of about 83.2% and the crystallinity index of the newspaper is 64.2. Composite samples were fabricated with three different fibre contents, namely 25%, 33%, and 48% (by weight). It was observed that on increasing the fibre content from 25% to 48%, the tensile strength and the modulus also increased by 54%–40%, respectively, along the fibre direction. It was observed that with 48% (w/w) fibre content, the waste paper composite yielded 70 MPa tensile strength and 6 GPa modulus in the fibre direction and 19 MPa tensile strength and 2.41 GPa modulus in the cross direction. The newspaper composite samples were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis.

The electromechanical properties of ionic polymer metal composites (IPMCs) are affected by many factors that are closely related to different physical and chemical preparation processes. This article focuses on the effects of chemical plating time on the electromechnical properties of IPMCs. First, a laminated electrode model, composed of a middle layer and a surface electrode layer, is presented in order to understand the factors affecting the electromechanical properties of IPMCs. Subsequently, the electromechanical properties were further performed by changing the chemical plating time of the polymer samples, and the impact effects were obtained by morphology characteristic analysis. The experiments revealed the mechanisms that lead to a decrease in surface electrode thickness under different chemical plating times as well as a decline in electromechanical properties.

Buccal drug delivery faces hurdles due to a lack of therapeutic efficiency resulting from saliva wash out. To meet this challenge, impregnated nanofibers with pharmaceutical agents could shorten total release duration as a result of higher surface area. Moreover, the electrospinning technique successfully functions in the field of nanofiber fabrication. Hence, in this study, composite nonwoven mesh containing Ziziphus jujuba extract was prepared by electrospinning, and release profile was studied in artificial saliva. The polymers used included chitosan and polyethylene oxide (PEO), which provided the desirable hydrophilicity that is essential for mucoadhesivity. Furthermore, the phenolic compound extracted from a plant namely Z. jujuba was used due to its oral healing effect. Morphology and chemical state of the composite film were also investigated through scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, respectively. Kinetic release of chitosan-PEO/phenolic compound nanofibers demonstrates a profile of Fickian diffusion dependency that delivered total phenolic ingredients in <75 min. The swelling behavior of composite type confirms Fickian diffusion and anomalous transport as a result of hydrophilic property of produced network and erosion mechanism on release phenomena, respectively. Results showed that impregnated electrospun patches of nanofibers can be promising for developing oral local drug delivery.

A novel type of aramid fibers coated with poly(ethylene glycol) methyl ether (PEGME)-modified multi-walled carbon nanotubes (MWCNTs) was designed using electrophoresis. Owing to the good interaction of MWCNT-PEGME with the matrix, the coated fibers were well dispersed in epoxy resin. Thin films of epoxy/aramid-MWCNT-PEGME were prepared by placing the modified aramid fibers in molds, and the epoxy resin was infused into them. 4,4′-Diaminodiphenylmethane was dissolved in epoxy before the resin was poured over the aramid fibers coated with MWCNT-PEGME. According to fracture surface studies, the modified fibers were completely miscible with the epoxy resin and the filler was dispersed well in the space between the aramid fibers. The tensile strength of neat resin was increased from 658 to 1198 MPa in 40 wt.% of fiber-loaded epoxy/aramid-MWCNT-PEGME 40 composite. The maximum flexural strength was also found to be higher for epoxy/aramid-MWCNT-PEGME 40 (1593 MPa). The glass transition temperature ( T g ) was studied using differential scanning calorimetry, in the range of 164–173°C. The tensile strength, modulus, flexural strength, and T g of epoxy/aramid fiber composites with unmodified fibers were found to be lower than those of epoxy/aramid-MWCNT-PEGME composites.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) was blended with poly(butylene adipate-co-terephthalate) (PBAT) by extrusion at different weight ratios (PHBH/PBAT: 100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100). Films were then prepared from the blends and characterized in terms of their morphological, rheological, mechanical and thermal properties. The morphological and rheological results indicated that PHBH/PBAT blends are immiscible but exhibit possible molecular interaction. The crystallization temperature of PHBH in the blends decreased, indicating that the addition of PBAT inhibited the crystallization of PHBH. Blending PBAT with PHBH improved the processability compared with that of pure polymers. The mechanical properties, including tensile strength, elongation at break and tear strength, increased with increasing PBAT content. The PHBH/PBAT 20:80 blend exhibited significantly improved mechanical properties, which was due to the reinforcing and toughening effect of the finely dispersed PHBH phase.

Advanced materials with excellent performance are in high demand in modern industry. Carbon fiber composites offer a number of advantageous mechanical properties. A significant improvement in fiber-reinforced composites can be achieved by dispersing a very small amount of nanofiller in the resin. Vacuum-assisted resin transfer molding (VARTM) is one of the most important processes for producing reinforced plastics. In this work, several composite samples were fabricated with the infusion of carbon nanofibers (CNFs) into the epoxy matrix using VARTM process. Using scanning electron microscopy (SEM), it was confirmed that CNFs were well dispersed in the resin. Bending tests were performed to investigate the mechanical properties of the samples, and SEM, to examine the fracture surfaces.

The wettability, interfacial shear strength (IFSS), and Weibull characteristics of oil palm empty fruit bunch (EFB) fibers were studied to evaluate the mechanical properties of EFB- and poly(lactic acid) (PLA)-based composites. The fiber surface was modified through ultrasound and poly(dimethyl siloxane) treatment. The effects of treatment on the morphology, wettability, and structure of fibers were examined by scanning electron microscopy, contact angle, and Fourier transform infrared spectroscopy analysis, respectively. In addition, the Weibull characteristic was used to find the variability in strength of the fibers with respect to surface treatment. Furthermore, the IFSS of EFB fiber-PLA sandwich was investigated through single-fiber pull-out test, using a less strenuous technique. The mechanical properties (tensile strength, tensile modulus, flexural strength, and flexural modulus) of the composites were determined through mechanical testing. A comparison was drawn among the properties of PLA, raw EFB fiber-based composites, and treated EFB fiber-based composites. Additionally, the inter- and intra-relationship of fiber treatment, wettability, and IFSS with the mechanical properties of the PLA/EFB composites were also accounted.

In this study, Matrimid mixed matrix membranes (MMMs) were prepared for CO 2 /CH 4 separation. MMMs were fabricated for improving the permeability and ideal selectivity of Matrimid membranes. Matrimid 5218 was used as a polymer matrix, and inorganic particles were used as additives. MMMs with a thickness of 33–38 μm were prepared at room temperature. The effects of the types and different amounts of additives on the permeability and ideal selectivity of MMMs were investigated by using a gas separation membrane unit. Scanning electron microscopy and atomic force microscopy images were used for checking the dispersion and agglomeration of additives within polymer matrices. Thermal gravimetric analysis showed that MMMs became much more thermally stable than pristine membranes. The decomposition temperatures (T d ) of MMMs were increased as compared to those of pristine membranes. The results of Fourier transform infrared spectroscopy analysis of MMMs and pristine membranes were recorded. The tensile strength of MMMs and pristine membranes was studied, and the results indicated that MMMs had higher values of tensile strength compared to pristine membranes.

This work seeks to explore the permeability dependence of polyurethane (PU)/polyethylene glycol (PEG) blend membranes on the molecular weight and composition of PEG constituent polymer. In this regard, gases with different polar nature were mixed (CO 2 /N 2 , CO 2 /CH 4 , and O 2 /N 2 ) and subjected to a series of PU/PEG blends prepared via solution casting method. With the alteration of the molecular weight (1000, 2000, and 6000 g/mol) and composition (0, 10, 15, and 20 wt.%) of PEG in the blend films, the potentials of membranes in controlling the permeation of gas molecules within the films were quantified, compared, and discussed. It is known that the introduction of PEG into PU-based membranes causes the films to become more flexible, which brings advantages from an application point of view. Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and scanning electron microscopy analyses were used to study the microstructural changes in the prepared PU/PEG blend membranes. The selectivity of the films was obviously displaced by the introduction of PEG, particularly when higher-molecular-weight PEGs were used and the resulting hybrid membranes were subjected to a mixture of CO 2 /CH 4 or CO 2 /N 2 gases.

A soda lignin, Protobind 2400, was blended at ratios up to thirty weight percent with polyolefins or the aliphatic-aromatic copolyester Ecoflex and films were cast with a twin-screw extruder. The mechanical properties, structure, and optical properties of the resultant films were characterized by tensile tests and microscopy. Films for all blends of this modified lignin were successfully cast without operational issues. Film elongation was maintained for both the polyolefins and Ecoflex. Lignin significantly increased the modulus of the polyethylene films but decreased the modulus of the polypropylene and Ecoflex films. Lignin was found as lamellae oriented in the machine direction of the polyolefin films, but as spherical domains in the Ecoflex film. It was concluded that the oriented lamellar structure was critical to the behavior of the polyolefin-lignin blends as optical polarization films (OPFs). Additional development around improvement of this property, which for the prototypes produced here was about one-tenth the efficiency of commercially available OPFs, to produce a sustainable OPF was recommended.

The objective of this study was to develop a bioplastic from industrial by-products. Commercial defatted rice bran (DRB) was extruded with 0–30% kraft lignin (KL) as a filler and 30% glycerol as a plasticizer. Firstly, the effect of extrusion temperature on the plasticized DRB’s processability was determined. Increasing the die extrusion temperature from 100°C to 150°C improved the extrudability by decreasing the die pressure and motor current. Subsequently, the effect of KL on plasticized DRB was studied. The addition of 10–30% KL improved DRB processability. The addition of 30% KL markedly lowered the die pressure in comparison to using a 150°C extrusion temperature. Moreover, KL addition decreased DRB viscosity determined by a capillary rheometer. These results were coherent with a decreased storage modulus in a rubber state and an increased tan δ height determined by a dynamic mechanical thermal analyzer (DMA). However, n values of DRB with 10–30% KL could not be explained by a simple mixing rule. This may be attributed to the interaction between DRB and KL, as shown by Fourier transform infrared (FTIR) spectra. KL addition increased Young’s modulus and the glass transition temperature ( T g ) of plasticized DRB. Therefore, blending DRB with KL is an effective way to improve polymer flowability at the processing temperature and mechanical properties at ambient temperature.

The industrial use of plastic injection moulding machines is widespread. However, few studies have examined the injection screw, which is one of the key components of moulding machines. Studies have demonstrated that a properly designed injection screw improves both the moulding quality and the production rate. Factors that affect the plasticisation properties of conventional standard reciprocating screws include the screw geometry, the screw operation settings, and the processed resins. An ideal standard reciprocating screw exhibits a high plasticising capacity and excellent melt temperature homogeneity; however, these properties typically conflict. Through simulation analysis, this study investigated the optimal design of a standard reciprocating injection screw used for plasticising polycarbonate resins. First, the Taguchi method was integrated with a commercial simulation programme to identify the key control factors affecting the plasticising rate of a screw and the temperature uniformity of the melt. Simulation results revealed that the screw diameter, rotation speed, metering channel depth, ratio of the screw length to the screw diameter, and compression ratio substantially influence performance. Consequently, grey relational analysis was adopted to optimise the design of an injection screw that ensures sufficient quality according to the plasticisation rate and the homogeneity of molten plastic.