Effect of MMT Clay on Mechanical,Thermal and Barrier Properties of Treated Aloevera Fiber/ PLA-Hybrid Biocomposites

Silicon - In this research, the PLA- biocomposite and PLA- hybrid biocomposites were prepared with twin screw extruder, two-roll mill, and compression molding method. The PLA based bio-composites...     

Mechanical and Water Absorption Properties of Natural Fibers/Polymer Biocomposites

In the present communication a study on the preparation and characterizations of Pine Needles (PN) reinforced polymers using Phenol-Formaldehyde (PF) as a novel polymer matrix has been reported. Pine Needles (PN) of different dimensions were used to prepare biocomposites. The influence of different fiber dimension on the mechanical properties of the composites was determined. Analysis of morphological (SEM) and thermal (TGA/DTA) properties of Pine Needles, PF resin and polymer composites have also been carried out. These polymer composites were further subjected to various standardized characterization tests such as swelling under different solvents, moisture absorption and chemical resistance analysis.     

Morphology,Thermal and Mechanical Properties of Poly (Styrene-Acrylonitrile) (SAN)/Clay Nanocomposites from Organic-Modified Montmorillonite

Poly (styrene-acrylonitrile) (SAN)/clay nanocomposites have successfully been prepared by melt intercalation method. The hexadecyl triphenyl phosphonium bromide (P16) and cetyl pyridium chloride (CPC) are used to modify the montmorillonite (MMT). The structure and thermal stability property of the organic modified MMT are, respectively characterized by Fourier transfer infrared (FT-IR) spectra, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results indicate that the cationic surfactants intercalate into the gallery of MMT and the organic-modified MMT by P16 and CPC has higher thermal stability than hexadecyl trimethyl ammonium bromide (C16) modified MMT. The influences of the different organic modified MMT on the structure and properties of the SAN/clay nanocomposites are investigated by XRD, transmission electronic microscopy (TEM), high-resolution electron microscopy (HREM), TGA and dynamic mechanical analysis (DMA), respectively. The results indicate that the SAN cannot intercalate into the interlayers of the pristine MMT and results in microcomposites. However, the dispersion of the organic-modified MMT in the SAN is rather facile and the SAN nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and the presence of small tactoids. The thermal stability and the char residue at 700°C of the SAN/clay nanocomposites have remarkably enhancements compared with pure SAN. DMA measurements show that the silicate clays improve the storage modulus and glass transition temperature (Tg) of the SAN matrix in the nanocomposites.     

Effect of Water Absorption on the Mechanical Properties of Sisal and Jute Fiber Composites

The variation of the ultimate stress and the elastic modulus of four different natural fiber-resin matrix composites was evaluated as a function of the aging of these composites in distilled water. Their diffusion coefficients and the maximum water content were also determined by fitting the experimental data to the Fickian model for diffusion. The composites analyzed were the common jute- and sisal-polyester matrix as well as jute- and sisal-epoxy resin matrix. The overall mechanical behavior observed could be qualitatively explained by the topographic aspects generated at the fracture surfaces. The jute-epoxy composite showed the best properties over all the immersion times analyzed. A strong fiber-matrix interface was developed for this composite and is partially responsible for its better behavior. The experimental data also show that the sisal fibers are more affected by water than jute fibers.     

玻纤增强聚酰胺6/蒙脱土复合材料的制备及其力学性能研究

通过螺杆挤出法制备了玻璃纤维增强聚酰胺6/蒙脱土复合材料,利用电子万能试验机对复合材料的力学性能进行了测量,并对实验结果进行了分析。结果表明,随着玻璃纤维含量的增加,聚酰胺6/蒙脱土/玻璃纤维复合材料的拉伸强度和冲击强度相应地增大,且长度为12mm的玻璃纤维增强的复合材料比6mm玻璃纤维增强的复合材料高;当玻璃纤维含量为10%(质量分数,下同)时,12mm玻璃纤维增强的复合材料的拉伸强度和冲击强度分别比聚酰胺6/蒙脱土复合材料提高了17.4%和84.1%。     

PLA/Kenaf/APP Biocomposites: Effect of Alkali Treatment and Ammonium Polyphosphate (APP) on Dynamic Mechanical and Morphological Properties

Kenaf-filled polylactic acid (PLA) biocomposites were prepared using dry blending, twin screw extrusion and compression molding. PLA was blended with raw and alkali treated kenaf, polyethylene glycol and ammonium polyphosphate (APP). Dynamic mechanical properties of biocomposites were investigated by dynamic mechanical analysis. Storage modulus of composites decreased, while magnitude of damping peaks increased with increase in APP content. The T _g of composites shifted to lower values with APP addition. Alkali treatment improved interfacial adhesion between PLA and kenaf. SEM analysis indicates good dispersion of APP in PLA matrix, however interfacial adhesion between PLA and matrix decreased with increasing APP content.     

聚丙烯/芦苇纤维复合材料力学及热性能的研究

以聚丙烯接枝马来酸酐(PP-g-MAH)为增容剂,制备了聚丙烯(PP)/芦苇纤维复合材料。采用万能拉力试验机、扫描电子显微镜(SEM)和热重分析仪(TGA)对复合材料的力学性能、断面形态以及热性能进行了表征。研究结果表明:添加增容剂可以改善芦苇纤维与PP基体的界面结合性,从而提高了PP/芦苇纤维复合材料的拉伸性能、弯曲性能以及热稳定性。     

蒙脱土对PET结晶性能、热稳定性和力学性能的影响

通过熔融共混法制备了聚对苯二甲酸乙二醇酯(PET)／蒙脱土复合材料，用X-射线衍射和透射电镜对蒙脱土在基体中的分散情况进行了表征。研究了蒙脱土对PET结晶性能、热稳定性和力学性能的影响。结果表明，蒙脱土在PET结晶过程中起异相成核作用，明显提高了PET的结晶速率；基体中分散的蒙脱土片层结构可显著改善其热稳定性，加入3％(质量含量，下同)蒙脱土时，起始热分解温度提高22℃，热变形温度提高41℃；加入1％时，材料拉伸强度提高25％，缺口冲击韧性略有下降，此时材料有较好的综合力学性能。     

Influence of Mesoporous Silica and Butyral Content on the Mechanical,Water Absorption,and Permeability Properties of in situ Synthesized Silica/PVB Nanocomposite Films

Poly(vinyl butyral)–silica nanocomposites were synthesized in situ with three different degrees of butyral and with varying silica content for each vinyl butyral polymer ratio. The glass transition temperatures of the polymer nanocomposites were found to be ～40–46 and ～52°C for the neat polymer, respectively. The 4 wt% silica loaded film showed higher strength and lower strain to failure compared with the neat polymer. The matrix with 0.5 and 0.75 butyral:alcohol for 2.5–4 wt% silica exhibited good water vapor transmission and the efficiencies of these films were 50% higher than their encapsulated pristine polymer films.     

木质纤维/PP复合材料吸水性能研究

采用模压成型工艺制备了木质纤维/PP木塑复合材料。测试了复合材料的24h吸水率和吸水厚度膨胀率,用体视显微镜对复合材料的微观结构断面进行了观察。结果表明:木质纤维质量分数为30%,粒径为100目时,复合材料的防水性能较好。     

PB/红麻复合材料的力学性能研究

采用硅烷偶联剂KH550、丙烯酸丁酯(BA)对红麻进行表面改性,通过模压成型工艺制备了聚丁烯(PB)/红麻复合材料,探讨了KH550、PP-g-MAH、红麻-g-PBA以及红麻含量对PB/红麻复合材料力学性能的影响,并利用扫描电镜对复合材料的微观形貌进行观察。结果表明:采用PP-g-MAH处理的复合材料的界面结合最强,当红麻含量为20%时,其拉伸强度和弯曲强度最大,分别为24.08 MPa和29.32 MPa,与纯PB相比分别提高了25.94%和69.50%。     

Influence of Nanogels on Mechanical, Dynamic Mechanical, and Thermal Properties of Elastomers

Use of sulfur crosslinked nanogels to improve various properties of virgin elastomers was investigated for the first time. Natural rubber (NR) and styrene butadiene rubber (SBR) nanogels were prepared by prevulcanization of the respective rubber lattices. These nanogels were characterized by dynamic light scattering, atomic force microscopy (AFM), solvent swelling, mechanical, and dynamic mechanical property measurements. Intermixing of gel and matrix at various ratios was carried out. Addition of NR gels greatly improved the green strength of SBR, whereas presence of SBR nanogels induced greater thermal stability in NR. For example, addition of 16 phr of NR gel increased the maximum tensile stress value of neat SBR by more than 48%. Noticeable increase in glass transition temperature of the gel filled systems was also observed. Morphology of these gel filled elastomers was studied by a combination of energy dispersive X-ray mapping, transmission electron microscopy, and AFM techniques. Particulate filler composite reinforcement models were used to understand the reinforcement mechanism of these nanogels. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

蒙脱土对热塑性淀粉结晶和力学性能的影响

用熔融挤出方法制备的甘油塑化热塑性淀粉(GTPS)/蒙脱土(MMT)复合材料,可以有效抑制GTPS长时间放置的结晶行为,提高其力学性能。不同相对湿度下复合材料、GTPS、淀粉的X ray衍射说明,MMT对GTPS结晶有抑制作用;力学测试表明,随着w(MMT)=0%提高到30%,复合材料最大应力达到27 31MPa,应变从85 3%下降到17 8%,杨氏模量达到206 7MPa,断裂能从1 921N·m下降到1 723N·m。红外(FTIR)谱图显示复合材料中淀粉分子的碳氧(C—O)基团向高波数移动,蒙脱土中可反应性羟基(OH)向低波数移动。这表明蒙脱土分子可反应OH和淀粉分子OH之间有氢键形成,使GTPS中淀粉分子之间氢键难以形成,蒙脱土在复合材料中起到阻隔剂的作用,是抑制GTPS结晶的主要原因;扫描电子显微镜(SEM)显示,蒙脱土均匀分散在GTPS中,提高了材料力学性能。     

Preparation,Mechanical and Electrical Properties and Water Absorption Study of Novel Bisphenol-C-Formaldehyde-Acrylate Treated and Untreated Jute Composites

The depolarization current spectra for polyvinyledenefluoride (PVDF), poly methylmethacrylate (PMMA), and their double-layered samples have been recorded under different polarizing conditions. When double-layered sample is polarized at 323 K with high field, a new TSDC peak is observed that is inherent in PMMA and PVDF when considered individually. This is because of the trapping charge carriers at the PVDF–PMMA interface. The space charge peak is shifted toward the lower temperature side for the PMMA and PVDF samples; however, this trend of peak shifting was not found for double-layered samples. The trapping of charge carriers in the metal polymer interface is responsible for space charge peak. This trapping of charge carriers in polymer-polymer interface is interesting, and this process is responsible for interfacial polarization in double-layered samples.     

PVC-U/蒙脱土复合材料的制备与力学性能研究

采用聚氧乙烯-聚氧丙烯(EP)嵌段共聚物对钠基蒙脱土进行有机化处理改性,XRD测试结果表明嵌段共聚物插层进入了蒙脱土层间.用熔融共混法制备了聚氯乙烯/蒙脱土复合材料,并研究了钠基蒙脱土和EP改性的有机蒙脱土对复合材料力学性能的影响.研究结果表明,采用EP对MMT进行改性能够提高MMT与PVC之间的相容性,PVC-U/MMT-EP复合材料的力学性能得到明显提高,EP对MMT改性是制备有机改性蒙脱土的有效方法之一.     

PMMA/蒙脱土纳米复合材料的结构及热性能

以甲基丙烯酸二甲胺基乙酯和1-溴正十六烷为原料合成了1种新型的带双键长碳链季铵盐甲基丙烯酰氧乙基十六烷基二甲基溴化铵(MHAB).用MHAB对钠基蒙脱土进行改性得到有机蒙脱土(OMMT).通过本体原位插层聚合制备了的聚甲基丙烯酸甲酯/蒙脱土纳米复合材料.MHAB的结构通过核磁共振氢谱(1H-NMR)表征.X射线衍射(XRD)测得OMMT的001面层间距(d001)从1.25 nm扩大到2.72 nm.XRD和透射电镜(TEM)测试证明蒙脱土质量分数为5%,8%时完全以剥离片层形式存在于复合材料中.差示扫描量热仪(DSC)和热失重仪(TG)测试表明复合材料的玻璃化转变温度和外推起始热失重温度都随着蒙脱土的含量增加而提高.     

表面改性超高相对分子质量聚乙烯纤维的热性能研究

采用铬酸刻蚀和化学气相沉积聚吡咯处理了超高相对分子质量聚乙烯(UHMWPE)纤维。用DSC、DMA、X-射线衍射及SEM分析了纤维的热力学性能、结晶情况及纤维的表观形貌。结果表明,铬酸处理及化学气相沉积聚吡咯处理后,纤维的耐热性均有所提高,纤维表面变得更加粗糙,其中化学气相沉积聚吡咯处理的纤维变化更明显。     

PHET/PF原位复合材料力学、动态力学和热性能研究

自行合成了端羟基的热致性聚酯液晶(PHET),采用原位复合的方法制备了热致性聚酯液晶(PHET)/酚醛树脂(PF)原位复合材料,研究了PHET的用量对PHET/PF原位复合材料的冲击强度、弯曲强度、动态力学性能、热性能等的影响。结果表明,PHET的加入可以提高PHET/PF原位复合材料的力学性能、动态力学性能和热性能,当PHET质量分数为7.5%时,原位复合材料的冲击强度、弯曲强度和玻璃化转变温度(Tg)分别提高了44.69%、44.68%和22.9℃。在200℃时,PHET/PF共混物中液晶丝状织态结构明显且分布连续。     

Viscoelastic Properties of Montmorillonite Clay/Polyimide Composite Membranes and Thin Films

Montmorillonite clay, cloisite 30B (nanoclay), was successfully dispersed in a polyimide (PI) matrix by in situ condensation polymerization followed by solution casting and thermal imidization. Wide angle X-ray diffraction, WAXD, test was used to study the structure of cloisite 30B clay powder and nanoclay/polyimide composites. The WAXD spectra of nanoclay powder and the composites show one major diffraction peak at 4.76° and 6°, respectively, suggesting that the d-spacing of nanoclay was decreased by about 26% after composite film processing. The viscoelastic property of polyimide and nanoclay/polyimide composite was studied by using dynamic mechanical spectrometer. The storage modulus and glass–rubber transition temperature of nanoclay/polyimide composites increases with increasing volume fraction of clay. The storage modulus of the composites in the rubbery plateau region, (T > 400 °C) increased remarkably with increasing volume fraction of clay. A modulus enhancement, (E_C/E_M) of about three orders of magnitude, (E_C/E_M ~1,440) was obtained for nanoclay/polyimide composite containing 6.8 vol% of nanoclay. The tangent of the loss angle (tan δ) for the composites, decreased with increasing volume fraction of nanoclay. The observed decrease in tan δ with increasing volume fraction of clay is consistent with the established trend of increasing storage modulus and glass–rubber transition temperature with increasing volume fraction of nanoclay. The phenomenal increase in the rubbery plateau storage modulus and glass–rubber transition temperature with increasing volume fraction of clay is believed to be due to increased restriction of chain motion with increasing nanoclay volume fraction.     

Effect of Coupling Agent Concentration,Fiber Content,and Size on Mechanical Properties of Wood/HDPE Composites

In this study, the influence of coupling agent concentration (0 and 3 wt%), wood fiber content (50, 60, 70, and 80 wt%), and size (40–60, 80–100, and 160–180 mesh) on the mechanical properties of wood/high-density-polyethylene (HDPE) composites (WPCs) was investigated. WPC samples were prepared with poplar wood-flour, HDPE, and polyethylene maleic anhydride copolymer (MAPE) as coupling agent. It was found that the tensile properties and the flexural properties of the composites were improved by the addition of 3 wt% MAPE, and the improved interfacial adhesion was well confirmed by SEM micrographs. It was also observed that the best mechanical properties of wood/HDPE composites can be reached with larger particle size in the range studied, while too-small particle size was adverse for the mechanical properties of wood/HDPE composites. Moreover, the tensile modulus, tensile strength, and flexural strength of WPCs decreased with the increase in fiber content from 50 to 80 wt%; the flexural modulus of WPCs increased with the increase in fiber content from 50 to 70 wt% and then decreased as the fiber content reached 80 wt%. The variances in property performance are helpful for the end-user to choose an appropriate coupling agent (MAPE) concentration, wood fiber content, and particle size based on performance needs and cost considerations.