Preparation and characterization of composites of polyethylene with polypyrrole‐coated wollastonite

Composite sheets of polyethylene and polypyrrole‐coated wollastonite were prepared by extrusion and compression molding. Four compatibilizers were also evaluated, poly(ethylene‐co‐methyl acrylate) (EMA), maleated polyethylene (MAPE), poly(ethylene‐co‐vinyl alcohol) (EVOH), and poly(vinyl alcohol) (PVOH). The composite materials were characterized using X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM), Raman spectroscopy, and mechanical properties determined by tensile tests. SEM micrographs showed that significantly improved interactions occurred between the PE matrix and polypyrrole‐coated wollastonite particles in the presence of EMA, MAPE, and EVOH. Raman spectroscopy confirmed that the polypyrrole coating on the wollastonite particles was not thermally degraded during melt processing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of electroconductive polypyrrole–thermoplastic composites

Polypyrrole–thermoplastic composite films were obtained by casting. Homogeneous films were prepared with dispersant poly(vinyl methyl ether) or poly(vinyl ethyl ether) by two methods. Electric conductivity, morphology, mechanical properties, and sensitivity to H₂O₂ in water were studied. Composites of polypyrrole with poly(vinyl chloride) carboxylated and poly(vinyl methyl ether) presented improved mechanical and electrical properties compared with other composites studied. These films were sensitive to H₂O₂ in water, showing a significant change in electric resistance. This change is discussed in relation to the H₂O₂ concentration and the exposure time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1498–1506, 2001     

Synthesis and characterization of polypyrrole‐au coated SiO2@poly(4‐vinylpyridine) composites

Microspheres with silica as core and poly(4‐vinylpyridine) (P4VP) as shell were synthesized. AuCl ions were bound by P4VP chains to form the complex, which acted both as an oxidant of pyrrole monomers and as a source of Au atoms. By vapor phase polymerization, the PPy and Au nanoparticles were simultaneously formed on the surfaces of SiO₂@P4VP microspheres. The core‐shell structure was confirmed by transmission electron microscopy. The surface morphologies of the composites were observed by scanning electron microscopy. The molecular structures of composites were characterized in detail by Raman spectra, X‐ray diffraction, and X‐ray photoelectron spectroscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

阻燃香蕉纤维增强聚乳酸复合材料的制备与表征

采用乙酰柠檬酸三丁酯(ATBC)作为增塑剂增塑聚乳酸,添加改性香蕉纤维和膨胀型阻燃剂(IFR)制备阻燃香蕉纤维增强聚乳酸复合材料.研究结果表明,偶联剂处理纤维的效果最好,使复合材料的拉伸、弯曲强度分别达到57.49MPa、101.80MPa,与扫描电子显微镜(SEM)的结果一致;IFR含量为5份(以聚乳酸为100份计)时综合性能最佳,材料的极限氧指数达到了 32.8%,垂直燃烧实验达到了 V-0 级(UL-94),材料的拉伸和弯曲强度分别为43.97 MPa 和87.95MPa,效果最好.热失重研究结果表明,阻燃香蕉纤维的加入能明显提高聚乳酸的热分解温度和残炭量.     

Preparation and EMI shielding properties of nickel‐coated PET fiber filled epoxy composites

Electrically conductive composites were prepared using epoxy resin (EP) as matrix and nickel‐coated polyethylene teraphthalate (PET) fibers as filler. The fibers were coated with nickel by plating and ultrasonic electroless deposition techniques. The coaxial transmission line method was used to measure the electromagnetic interference (EMI) shielding effectiveness of the nickel‐coated PET fiber/EP composites. The contents of nickel and phosphorus in the coating were determined by X‐ray photoelectron spectroscopy (XPS). As a result, the ultrasonic electroless nickel‐coated PET fiber/EP composites showed excellent electrical conductive capability and better EMI shielding effectiveness due to higher content of nickel and lower content of phosphorus in the coating than conventional plated nickel‐coated PET fiber/EP composites. POLYM. COMPOS., 27:24–29, 2006. © 2005 Society of Plastics Engineers     

Preparation and characterization of poly[(butylene succinate)‐co‐(butylene adipate)]/carbon nanotube‐coated silk fiber composites

Biodegradable composites consisting of aliphatic polyesters (poly[(butylenes succinate)‐co‐(butylenes adipate)] (PBSA)) and Bombyx mori silk fibers coated with carbon nanotubes (CNTs) were prepared by melt compression molding. The mechanical properties of PBSA were enhanced by the incorporation of a small amount (3 wt%) of CNT‐coated silk fibers, while allowing its potential biodegradability to be retained, which could make these composites good candidates for commodity materials such as general‐purpose plastics. This improvement is attributed to the interactions between PBSA and CNT‐coated silk fibers in the composites. The average interfacial shear strength of the composites consisting of CNT‐coated silk fibers and PBSA matrix was 1.7 MPa, as measured by the microbond droplet test, while that of composites consisting of pure silk fibers and PBSA was only 1.1 MPa. The morphology of the CNT‐coated silk fiber‐reinforced composites was observed using scanning electron microscopy. Copyright © 2007 Society of Chemical Industry     

Surface structure of conductive polypyrrole‐containing composites

The surface structures of polypyrrole/silicon crosslinked poly( styrene/butyl acrylate/hydroxyethyl acrylate) (PSBH) conductive composite films were investigated by X‐ray photoelectron spectroscopy and scanning electron microscopy. It was found that the conductive composite films were of a “sandwich” structure, and the surfaces greatly differ in chemical compositions and phase morphologies from the bulk. The Si and N contents exhibit opposite gradient change with the measured depth of the two surface layers in the composite films, namely, the decrease in Si content and the increase in N content with increase in the depth of the surface layers. However, the N^δ+/N ratios in polypyrrole decreased with the measured depth of the conductive composite film. It was also found that the conductive composite film based on silicon crosslinked matrix exhibits more environmental stable than that based on linear matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 95–101, 1999     

Preparation of polypropylene fiber/banana fiber composites by novel commingling method

Short natural fiber thermoplastic composites are usually fabricated by melt mixing or solution mixing followed by conventional methods like injection molding or compression molding. In melt mixing, the fibers are subjected to high shear and this damage the natural fiber. In solution mixing, the use of the organic solvent is essential and its use is hazardous. Development of a novel method commingling to prepare polypropylene (PP)/short natural fiber composite is the main objective of this study. The influence of fiber loading on the mechanical properties of the composites prepared by the above method has been evaluated. The applications and limitations of several equations to predict physical properties such as tensile strength and modulus of the composites have been described. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Electrically conductive composites of polyurethane derived from castor oil with polypyrrole‐coated peach palm fibers

Electrically conducting fibers were prepared through in situ oxidative polymerization of pyrrole (Py) in the presence of peach palm fibers (PPF) using iron (III) chloride hexahydrate (FeCl₃·6H₂O) as oxidant. The polypyrrole (PPy) coated PPF displayed a PPy layer on the fibers surface, which was responsible for an electrical conductivity of (2.2 ± 0.3) × 10⁻¹ S cm⁻¹, similar to the neat PPy. Electrically conductive composites were prepared by dispersing various amounts of PPy‐coated PPF in a polyurethane matrix derived from castor oil. The polyurethane/PPy‐coated PPF composites (PU/PPF–PPy) exhibited an electrical conductivity higher than PU/PPy blends with similar filler content. This behavior is attributed to the higher aspect ratio of PPF–PPy when compared with PPy particles, inducing a denser conductive network formation in the PU matrix. Electromagnetic interference shielding effectiveness (EMI SE) value in the X‐band (8.2–12.4 GHz) found for PU/PPF–PPy composites containing 25 wt% of PPF–PPy were in the range −12 dB, which corresponds to 93.2% of attenuation, indicating that these composites are promising candidates for EMI shielding applications. POLYM. COMPOS., 38:2146–2155, 2017. © 2015 Society of Plastics Engineers     

Preparation and characterization of EVA–sisal fiber composites

In this work, composites of an EVA polymer matrix and short sisal fiber were characterized. The physical‐morphological as well as chemical interactions between EVA and sisal were investigated. When the samples were prepared in the presence of dicumyl peroxide, the results suggest that crosslinking of EVA as well as grafting between EVA and the sisal fibers took place. Morphological changes were studied by scanning electron microscopy (SEM). Results from Hg‐porosimetry, SEM, Fourier transform infrared spectroscopy, surface free energy, and gel content strongly indicate grafting of EVA onto sisal under the composite preparation conditions, even in the absence of peroxide. The grafting mechanism could not be confirmed from solid‐state ¹³C NMR analysis. The grafting had an impact on the thermal and mechanical properties of the composites, as determined by differential scanning calorimetry and tensile testing. Thermogravimetric analysis results show that the composites are more stable than both EVA and sisal fiber alone. The composite stability, however, decreases with increasing fiber content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1607–1617, 2006     

Antibacterial property on Gram‐positive bacteria of polypyrrole‐coated fabrics

Antibacterial activity against Gram‐negative bacteria of polypyrrole‐coated fabrics has been demonstrated in the past. In this work, biocidal efficacy of polypyrrole has been evaluated against Gram‐positive bacteria on textiles with different polypyrrole loading. Excellent bacterial reduction (≥99%) was found on cotton fabrics containing more than ～9 wt % of polypyrrole. Polypyrrole loading can be greatly reduced in presence of silver. Silver‐containing fabrics used in this work alone does not guarantee a complete biocidal effect, but the addition of just 2 wt % of polypyrrole showed a bacteria reduction of 99%. Moreover, stability to different washing procedures of the antibacterial activity was evaluated. Fabrics were characterized by scanning electron microscopy, energy dispersive X‐ray analysis, and infrared spectroscopy. Stability of the coating was assessed by abrasion tests. PPy showed excellent fastness to abrasion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41670.     

Conducting rubberlike copolymer–carbon fiber composites

Electrically conductive rubberlike copolymer–carbon fiber composites have been prepared by either a solution method or a concentrated emulsion method. In the former procedure, carbon fibers were introduced with stirring in a copolymer–toluene solution, and the polymer–fiber composites were precipitated by extracting the solvent with methanol. In the latter procedure, a pastelike concentrated emulsion of copolymer–toluene solution in an aqueous solution of sodium dodecylsulfate (SDS) was first formed, and the carbon fibers were mechanically blended with the concentrated emulsion. The polymer–carbon fiber composites were precipitated by extracting the toluene and water with methanol. Four kinds of rubberlike copolymers have been used: styrene/ethylene–butylene/styrene triblock copolymer (SES), styrene/butadiene/styrene triblock copolymer (SBS), ethylene/propene/ethylene triblock copolymer (EPE), and ethylene/vinylacetate copolymer (EVA). Short (L = 0.1 mm)- and medium (L = 5 mm)-length carbon fibers were employed. The composites were hot-pressed in a Laboratory Press to form a sheet. The effects of the two methodologies on the electrical conductivity and mechanical properties of the sheets were investigated by changing the type of polymer, the size of the carbon fibers, the volume fraction of the carbon fibers in the composites, and the hot-pressing temperature. Composites with electrical conductivities in the range of 5–14 S/cm, tensile strengths in the range of 10–17 MPa, and elongations at break point larger than 200% were obtained. The conductivities of the composites prepared with the short fibers were by two orders of magnitude smaller than those prepared with medium-size fibers. © 1994 John Wiley & Sons, Inc.     

Preparation and characterization of poly (vinyl butyral)‐leather fiber composites

This study reports the preparation and characterization of composites with recycled poly (vinyl butyral) (PVB) and wet blue leather fiber with leather contents of 30, 50, and 70 wt%, using an extruder equipped with a Maillefer single screw operated with a flat extrusion die. The components of the composites were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy (FTIR). After extrusion, the PVB/leather composite plates were compression‐molded to obtain specimens for testing the tensile properties, hardness, abrasion resistance, and tear strength. The morphologies of the composites were analyzed by scanning electron microscopy (SEM). The DMA and FTIR analyses showed that the recycled PVB contained plasticizer remained in the polymer matrix after extrusion. The SEM analysis revealed good interfacial adhesion between the PVB matrix and the leather fibers. Increasing the leather content in the composites led to a significant increase in the tensile modulus and a reduction in the tensile strain at breaks. The Shore hardness of the composites increased with the wt% of leather, whereas the abrasion resistance decreased. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers.     

Preparation and characterization of LDPE and PP—Wood fiber composites

Natural fiber reinforced composites is an emerging area in polymer science. These natural fibers are low cost fibers with low density and high specific properties. These are biodegradable and nonabrasive. The natural fiber composites offer specific properties comparable to those of conventional fiber composites. However, in development of these composites, the incompatibility of the fibers and poor resistance to moisture often reduce the potential of natural fibers, and these draw backs become critical issue. Wood‐plastic composites (WPC) are a relatively new class of materials and one of the fastest growing sectors in the wood composites industry. Composites of wood in a thermoplastic matrix (wood–plastic composites) are considered a low maintenance solution to using wood in outdoor applications. WPCs are normally made from a mixture of wood fiber, thermoplastic, and small amounts of process and property modifiers through an extrusion process. In this study, Wood–plastic composites (WPC) are produce by adding a maleic anhydride modified low density polyethylene coupling agent to improve interfacial adhesion between the wood fiber and the plastic. Mixing is done with twin screw extruder. Subsequently, tensile strength, the modulus of elasticity, % elongation, hardness, Izod impact strength, melt flow index (MFI), and heat deflection temperature (HDT) are determined. Thermal transition temperatures and microstructure are determined with DSC and SEM, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of vitrified CeO2 coated cBN composites

The performances of vitrified cBN composites are deeply affected by the wettability of vitrified bonds on cBN particles. CeO₂ coated cBN particles were successfully prepared for the further improvement of the covering and wetting of cBN by vitrified bonds. The microstructure and properties of vitrified cBN composites were characterized by scanning electron microscope (SEM), hot stage microscope (HSM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and flexural strength. Results showed that the prepared CeO₂ coating on the surface of cBN was uniform and dense. Besides, the improved wettability of vitrified bonds on CeO₂ coated cBN particles accompanied with the formation of Ce–O–Al and N–Si confirmed by XPS were supposed to conduce to enhancing the holding power of the vitrified bonds to cBN particles, which resulted in increasing the flexural strength of vitrified cBN composites by 9.16%. Thus, coating cBN with CeO₂ was a potential and effective method to obtain vitrified cBN composites with higher flexural strength.     

Novel hollow‐fiber anion‐exchange hybrid membranes: Preparation and characterization

To develop ion‐exchange membranes for application in severe conditions, such as those with high temperatures, strongly oxidizing environments, or organic solvents, new hollow‐fiber anion‐exchange hybrid membranes were prepared by the immersion of brominated poly(2,6‐dimethyl‐1,4‐phenylene oxide) base hollow fibers in a tetraethoxysilane–ethanol solution followed by sol–gel and quaternary amination. Compared to conventional polymeric charged membranes, the prepared hybrid membranes were higher in both thermal and dimensional stabilities. The results suggest that tetraethoxysilane concentration was an important factor affecting the membrane's intrinsic properties. When the tetraethoxysilane concentration was in the range 15–45%, the final hollow‐fiber anion‐exchange hybrid membranes had an ion‐exchange capacity of 1.9–2.0 mmol/g, a water uptake of.83–1.23 g of water/g of dry weight, and a dimensional change ratio of 13–18%. An evaluation on the membranes' separation performances is underway. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and properties of PBS/sisal‐fiber composites

We report the preparation of polybutylene succinate (PBS)/sisal‐fiber (SF) composites. The effects of mixing temperature and of steam‐explosion pretreatment of SFs on the mechanical properties of the composites were investigated, and the mechanism of action was studied by infrared spectroscopy, scanning electron microscopy, and x‐ray photoelectron spectroscopy. The results indicate that as the mixing temperature increases, PBS flows better and can graft onto steam‐exploded sisal fiber (SESF), the interfacial bond property between SESF and PBS improves, and the mechanical properties of the composites improve. The mechanical properties of the composites are maximal for a mixing temperature of 200°C. The results also demonstrate that the cellulose content and the specific fiber surface area can be increased by steam‐explosion pretreatment, so that the mechanical properties of the composites can be improved. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Novel polyurethane elastomer continuous carbon fiber composites: Preparation and characterization

Preparation and characterization of novel polyurethane (PUR)–carbon fiber (CF) composites are reported. The reinforcement of PUR elastomers was achieved using unidirectional continuous CFs with different coatings (uncoated and epoxy and polyester resin coatings) by applying molding for the preparation of PUR‐CF composites. Considerable reinforcement of PUR was attained even at relatively low CF content, e.g., maximum stress and Young's modulus of PUR‐CF composite at CF content 3% (m/m) were found to be 3–5 and 4–10 times higher than those of the PUR‐matrix, respectively. In addition, a linear relationship between the Young's modulus and the CF content was found as well as linear variation of maximum stress with the CF content was also observed. The adhesion of CF to the PUR‐matrix was strong in each case as concluded from the strain–stress and the scanning electron microscopy (SEM) investigations. However, the extent of reinforcement of PUR at a given CF content was found to depend greatly on the coatings of CF, and increased in the following order: epoxy resin < polyester resin < uncoated. The effect of the coating of CF on the reinforcement of PUR is also discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 287–292, 2007     

Preparation and characterization of cellulose fiber/chitosan composites

Cellulose fiber/chitosan biodegradable rod (CF/CS rod) with layer‐by‐layer structure, good mechanical properties, and excellent X‐ray developing capability was successfully constructed via in‐situ precipitated method. As the ratio of CF to CS was 0.2/20 (wt/wt), the bending strength and bending modulus arrived at 124.1 MPa and 4.3 GPa, respectively, were significantly improved compared with pure CS rod. TGA indicated that the thermal stability of CS rod could be enhanced by mixing with CF, but fiber and matrix are partially compatible. SEM made clear that fibers were randomly dispersed in the CS matrix to connect layers of CS rod that can endure stress. FTIR spectra illuminated that small amount of Schiff base was formed due to the chemical reaction between fibers and CS matrix, which could enhance the mechanical combining stress of the interface. Thus, CF/CS rod has great potential to be used as internal fixation of bone fracture. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Electrical conductivity studies on water‐soluble polypyrrole–graphene oxide composites

Polypyrrole (PPy)–graphene oxide (GO) composites are synthesized via a soft‐chemical in situ method at different GO concentrations (10, 20, 30, 40, and 50 wt%) and with ammonium persulfate (APS) as the oxidant. The synthesized composites were characterized using Fourier transform infrared (FTIR) and ultraviolet‐visible light (UV–vis) spectroscopic studies, and their surface properties were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Characterization and surface morphology results indicate that PPy is adsorbed onto the graphene surfaces and/or fills the GO sheets. The temperature‐dependent DC conductivity of the polymer composite films in the 300–500 K range indicates a semiconducting behavior with increasing GO concentration in the PPy polymer. Based on morphological and conductivity studies, the large surface area and high aspect ratio of the in situ‐generated GO may have played an important role in the noticeable improvement in the electrical conductivity of the prepared composites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers