Thermo‐physical,thermal degradation,and flexural properties of betel nut husk fiber reinforced vinyl ester composites

This study aims to investigate the thermo‐physical, mechanical, and thermal degradation properties of betel nut husk (BNH) fiber reinforced vinyl ester (VE) composites. These properties were evaluated as a function of fiber maturity, fiber content, and fiber orientation. Thermo‐physical properties were analyzed experimentally using a hot disk TPS method. The introduction of BNH was found to reduce the thermal conductivity of neat VE. The thermal conductivity and thermal diffusivity of BNH reinforced VE composites decreased with the increase in fiber content. Short fiber BNH reinforced VE composites showed the lowest thermal conductivity as compared to the unidirectional and random nonwoven composites. The TGA analysis shows lower resin transition peak for the BNH reinforced VE composites than the peak of neat VE. Fiber maturity had a notable effect on the flexural modulus of the BNH fiber reinforced VE composites. Incorporation of 10 wt% BNH fibers into the composite has increased the composites' flexural modulus by 46.37%. However, further increases in the fiber content reduced both flexural strength and modulus of the composites. POLYM. COMPOS., 37:2008–2017, 2016. © 2015 Society of Plastics Engineers     

Pineapple leaf fiber reinforced thermoplastic composites: Effects of fiber length and fiber content on their characteristics

Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and low‐density polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0–25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dynamic mechanical properties of pineapple leaf fiber polyester composites

In the recent years, lignocellulosic fibers that originate from a renewable source have been found to provide good reinforcement in polymer matrices. Among the natural fibers, pineapple leaf fiber (PALF) exhibits excellent mechanical properties, besides possessing low density, high stiffness, and low cost. The dynamic mechanical properties, storage modulus (E′), and loss tangent of PALF‐reinforced polyester (PER) composites were evaluated at three frequencies 0.1, 1, and 10 Hz and temperatures ranging from 30 to 200°C. Addition of PALF of 30 mm length (aspect ratio 600) was found to increase the storage modulus leading to a maximum value at 40 wt%. The glass transition temperature (T_g) of the composite of 40 wt% showed a positive shift indicating high polymer/fiber interaction. A new relaxation is observed at 40 wt% showing the presence of a strong interphase at all aspect ratios. SEM photographs of fracture surfaces of composites confirm the results obtained from static and dynamic mechanical analysis. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Extrusion and mechanical characterization of PVC-leather fiber composites

Every year great quantities of chrome tanned leather wastes produced by the footwear and clothing industries are buried or burned. These practices produce several contaminants that are released into the environment. An alternative to disposing of these wastes is to reuse them. In this work, a method to use these wastes as filler in a polymer matrix is proposed. Also, a technique for processing the composite obtained by continuous extrusion is demonstrated. To evaluate this technique, a series of PVC-leather fiber composites were prepared and extruded through a flat die to produce sheets. The process produced a leather-like sheet that could be used in several applications. The influence of the filler content on the processability and the final properties of the composite sheets were evaluated. The tests revealed that the sheets are flexible and exhibit sufficient water absorption to be suitable for several applications in the footwear and clothing industry. Finally, the tests show that this composite can be formulated and processed at high productivity levels and at a low cost.     

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     

Preparation and characterization of artificial skin using chitosan and gelatin composites for potential biomedical application

A bioadhesive wound-dressing material based on the combination of gelatin and chitosan with a proper ratio was developed and successfully applied in biomedical fields. The composite films were prepared with increase in chitosan concentration in a fixed amount of gelatin and were evaluated for mechanical stability (e.g., tensile strength, elongation-at-break), water and buffer uptake capacity, water and buffer aging, molecular structure, morphology, thermal stability, and for biological properties (e.g., antimicrobial activity, cytotoxicity, in vivo wound-healing performance). It is noteworthy that the 10:3 (gelatin:chitosan) composite films showed the best physico-mechanical, thermal, and antimicrobial properties among the other ratios blend films. The improved mechanical and thermal stability of the 10:3 composite film suggested its promising use as carrier for controlled release drug. The composite film was evaluated using a rat model for in vivo tests to ascertain the applicability of the proper ratio of the chitosan and gelatin in the film for best wound-healing activity. Wound sites dresses with gelatin/chitosan composite films showed excellent rapid healing of the wound surface than those dressed with eco-plaster and gauze. Within a day after dressing with 10:3 composite film, the healing efficiency was found to be 80?%.     

Rheological characterization of HDPE/sisal fiber composites

The present paper summarizes an experimental study on the molten viscoelastic behavior of HDPE/sisal composites under steady and dynamic mode. Variations of the melt viscosity and die swell of the composites with an increase in shear rate, fiber loading, and coupling agent concentration have been investigated using capillary rheometer. The shear rate γ at the wall was calculated using Rabinowitsch correction applied to the apparent shear rate values. It was observed that the melt viscosity of the composites increased with the addition of fibers and maleic anhydride-grafted PE (MAPE). Die swell of HDPE also decreased with the addition of sisal fibers and MAPE. Further, the dynamic viscoelastic behavior of the composites was measured employing parallel plate rheometer. Time–temperature superposition was applied to generate various viscoelastic master curves. Temperature sweeps were also carried out to study the flow activation energy determined from Arrhenius equation. The fiber–matrix morphology of the extrudates was also examined using scanning electron microscopy. POLYM. ENG. SCI., 47:1634–1642, 2007. © 2007 Society of Plastics Engineers     

Fluorinated aramid fiber reinforced polypropylene composites and their characterization

Polymer fibers are one of the main substances used for the reinforcement of plastic composites. Surface modification of aramid fiber was performed by direct fluorination. The crystallinity and the decomposition temperature of the modified fiber were increased. Scanning electron microscope shows that the roughness increases in the modified fiber. Composites were prepared by using modified and unmodified fibers. It was shown that the mechanical and thermal properties increase for modified fiber reinforcing composites. To reduce the fiber degradation or breakdown, composites were prepared by solution casting method. POLYM. COMPOS., 28:462–469, 2007. © 2007 Society of Plastics Engineers     

长纤维增强热塑性复合材料的开发与应用

长纤维增强热塑性复合材料以其优异的性能成为高分子复合材料研发与应用的热点。笔者综述了长纤维增强热塑性复合材料的性能特征、研发历史与现状、产品形式与制造技术、应用状况,展望了长纤维增强热塑性复合材料的发展前景。     

炭纤维复合材料在运动自行车中的应用

介绍了炭纤维复合材料在运动自行车车架上的应用,并将其与目前应用于自行车制造的各种材料进行了比较,总结了它的主要特点,对炭纤维复合材料运动自行车现状及将来发展趋势进行了分析讨论.     

高性能纤维复合材料的研究及应用

高性能纤维复合材料是以高性能纤维作为增强材料,树脂作为基体,通过加工成型得到的复合材料,具有质轻、高强高模、抗疲劳、耐腐蚀、可设计性强、易加工成型等优异性能,得到广泛的应用。本文介绍了高性能纤维复合材料常用高性能纤维和常用树脂基体、复合材料界面和应用领域,并分析了国内高性能纤维复合材料发展存在的问题。     

Conducting polypyrrole‐coated banana fiber composites: Preparation and characterization

In this study, conducting banana fibers (BF) were obtained through in situ oxidative polymerization of pyrrole (Py) on the BF surface using ferric chloride hexahydratate (FeCl₃·6H₂O) as an oxidant. Suitable reaction conditions are outlined for the polymerization of Py: oxidant/monomer molar ratio, Py concentration and polymerization time of 2/1, 0.05 mol.L⁻¹ and 30 min, respectively. Under these conditions, high‐quality conducting fibers containing polyPy and BF (PPy‐BF) were obtained with an electrical resistivity as low as 0.54 Ω.cm. The PPy‐BF was blended with different concentrations of polyurethane (PU) by mixing the two components in a vacuum chamber and then applying compression molding. The electrical resistivity of composites with 25 wt% of PPy‐BF was around 1.8 × 10⁵ Ωcm, which is approximately 10⁸ times lower than that found for pure PU. Moreover, PU/PPy‐BF composites exhibited higher mechanical properties than pure PU and PU/PPy, indicating that these conducting fibers can also be used as reinforcement for polymer matrices. The properties of the PPy‐BF obtained by the method described herein open interesting possibilities for novel applications of electrically conducting fibers, from smart sensors to new conducting fillers that can be incorporated into several polymer matrixes to develop conducting polymer composites with good mechanical properties.POLYM. COMPOS., 2013. © 2013 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     

Preparation and characterization of light curable hybrid coating: Its potential application for dental restorative material

The objective of this study was to synthesize a dual-functional light curable resin by the reaction between acrylated cycloaliphatic epoxy resin and 3-isocyanatopropyltrimethoxysilane and investigate the performance of this oligomer in the preparation of resin-based composite restoratives. FT-IR and ²⁹Si-NMR were used to characterize the structure of the hybrids. The char yields of the hybrids increased with inorganic content comes from TEOS (tetraethylorthosilicate) and synthesized SiUA oligomers. Gel content of polymeric films was found to be between 95% and 98%. Swelling was found to be between 3.1% and 3.8%. Weight loss of coated human teeth in synthetic saliva solution was found to be among 1% and 2%. There was a systematic increase in the modulus and tensile strength with the increase of inorganic content. On the other hand, elongation at break did not changed. Prepared hybrid coating materials exhibited improvement in tensile properties and hardness, when photo chemically cured.     

Mechanical characterization of new glass fiber reinforced epoxy composites

Glass fiber reinforced plastic (GFRP) composites were made using CTPEGA [carboxyl terminated poly(ethylene glycol) adipate] modified epoxy as a matrix and characterized for their flexural properties, impact strength and interlaminar shear stress (ILSS). The volume fraction of glass was about 0.45 for all the composites. The concentration of CTPEGA in the matrix was varied gradually from 0 to 40 phr (parts per hundred parts of resin), to investigate the effect of CTPEGA concentration on the mechanical properties of the composites. It was found that the flexural strength and ILSS gradually decreases with increase in CTPEGA concentration. However, the impact strength of the composites increases up to 20 phr of CTPEGA concentration and decreases thereafter. Scanning electron microscope (SEM) analysis of the fracture surface indicates massive plastic deformation in modified epoxy based composites. Polym. Compos. 25:165–171, 2004. © 2004 Society of Plastics Engineers.     

Morphological characterization of polyetheretherketone–carbon fiber composites

The effect of processing conditions on the morphology of polyetheretherketone (PEEK) graphite reinforced composites (APC-2) has been characaterized. Differential scanning calorimetry was utilized to examine the effect of quench rate on recrystallization where a change in mechanism was observed at a rate of 5°C/min. Optical microscopy revealed a decrease in spherulite size and a reduced degree of transcrystallinity at the graphic fiber surface with increasing quench rates. Dynamic mechanical analysis indicated a change in relaxational processes in the T_g region with varying quench rates.     

Fabrication and characterization of polylactic acid/natural fiber extruded composites

In this work, the fabricated polylactic acid (PLA) and hybrid natural fiber (NF) biocomposites via a melt extrusion method were investigated. NFs from locally grown plants were utilized as fillers. Polyethene glycol (PEG) was used as the plasticizer to improve the processability of the PLA. The effect of PLA/NF biocomposite processing was assessed by mechanical characterization (tensile, modulus, strain at break, and impact tests), and thermal properties (thermogravimetric analysis and differential scanning calorimetry [DSC] analysis). The dynamic mechanical analysis (DMA), and thermo-mechanical analysis (TMA) of the samples were also analyzed. The mechanical properties of PLA/NF biocomposites improved as compared with that of PLA. The DMA findings show that the storage modulus and loss modulus exhibited a slight reduction for PLA/NF biocomposites compared with the PLA sample. In opposite, the glass transition temperature (T_g) from DSC thermogram results showed no obvious changes in values compared with the PLA sample. Furthermore, the findings of TMA showed a significant decrease in coefficient of thermal expansion values of PLA/NF biocomposites compared with those of PLA samples. The overall findings from this work indicated that PLA/NF biocomposites have the potential to make novel biocomposites and suitable for further application especially in biomedical applications due to its good stiffness, tensile strength, and dimensional stability.     

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.     

The application of fracture mechanics to short fiber composites

The fracture performances of three short glass fiber-reinforced polymer composite systems, PET with 30 wt% glass, nylon 6/6 with 33% glass fibers, and a nylon 6 and 6/6 copolymer with 33% glass, have been characterized using both standard mechanical characterization and fracture mechanics. These results have been compared to fracture tests of an experimental chair base. None of the characterizing techniques was successful in predicting the chair base fracture performances of the materials when the tests were conducted on standard 3-mm-thick test specimens. When larger specimens with comparable morphologies to the chair base were tested, the fracture mechanics tests compared favorably to the chair base fracture tests while the tensile test results were inconsistent in their predictive ability. The findings emphasize the importance of testing laboratory specimens that are similar in morphology to the final part and suggest that fracture mechanics methodologies can be used in materials selection of glass reinforced systems for structural applications. However, for quantitative design, it is necessary to address issues regarding the nature of the inherent flaw in the finished parts.