The Effect of Environmental Treatments on Fiber Surface Properties and Tensile Strength of Sugar Palm Fiber-Reinforced Epoxy Composites

Fiber glass has been used widely in manufacturing industries, especially marine industries, because of low cost and high strength. However, glass fiber can cause acute irritation to the skin, eyes, and upper respiratory tract. This study looked at the possibility of substituting glass fiber with natural fiber in composite materials. The surface properties of sugar palm fiber (Arenga pinnata) were modified using seawater and freshwater as treatment substances. This led to biological, chemical, and water degradation of the sugar palm fiber. Morphological and structural changes in the fibers were investigated using a scanning electron microscope (SEM). A series of tensile tests based on ASTM D638-99 was carried out on epoxy composites with 15% sugar palm fiber by volume. It was found that seawater and freshwater treatments improved the surface properties of the sugar palm fiber and thus resulted in better adhesion quality as compared to untreated fiber. An improvement in tensile strength also supported this finding. Treatment with seawater for 30 days proved to be the best, with 67.26% increase in tensile strength.     

玻纤对湿热环境下的环氧复合材料拉伸性能的影响

为了研究湿热环境下玻璃纤维对环氧复合材料拉伸性能的影响,建立试验模型,以不同浸润剂配方生产的相同单丝直径及TEX值的玻璃纤维进行浸胶制样,样条在95℃下1%浓度的NaCl溶液中浸泡24 h、72 h后,样条拉伸强度变化,从而得出玻璃纤维对在湿热环境下环氧复合材料拉伸性能的影响,即选用合适的偶联剂生产的玻璃纤维,对复合材料湿态拉伸强度有明显的提升。     

三维正交机织玄武岩/芳纶混编复合材料的拉伸和剪切性能研究

本文设计和制作了两种混杂模式的三维正交机织玄武岩/芳纶混编复合材料,分别是层间混杂和层内混杂模式。对其拉伸性能和剪切性能进行了测试和分析,结果表明,层内混杂复合材料的拉伸性能和剪切性能比层间混杂复合材料的好,层内混杂复合材料的归一化强度和归一化模量分别比层间混杂复合材料的高22.12%和16.9%,层内混杂复合材料的剪切强度和剪切模量分别比层间混杂复合材料的高19.61%和26.03%;对于层间混杂复合材料,纬向的归一化强度比经向的高4.06%,但厚度方向上纱线的存在和织造工艺中经纱预加张力的影响,使纬向的归一化模量比经向的降低11.44%。     

Mechanical and Damping Properties of Glass Fiber and Mica-Reinforced Epoxy Composites

Mica/glass fiber-reinforced epoxy with 0° and 45° ply angle were prepared by hand lay-up and the mechanical and damping properties were studied. Results show that the addition of mica resulted in decrease of tensile strength and modulus for both composites. Althogh flexural strength and modulus of composites with 45° appeared a maximum at 5 phr mica loading, that of composites with 0° reached a maximum at 10 phr mica loading. For composites with 0°, damping ratio reaches maximum at 5 phr mica. Although for composites with 45°, damping ratio decrease with increasing mica loading.     

Mechanical Behavior of Fiber-Reinforced Cement-Based Composites

The use of fibers in a cement-based matrix can fundamentally improve its mechanical properties. Such improvement may lead to a new class of cement-based materials. Further developments depend on an understanding of the interaction between different fibers and cement-based matrices. The current knowledge on the mechanical behavior of fiber-reinforced cement-based composites is summarized. Toughening mechanisms, interface properties, and tensile response of fiber-reinforced cement-based composites are presented. Various theoretical approaches used to describe the mechanical behavior of fiber-reinforced composites are reviewed.     

Fabrication and Characterization of H. sabdariffa Fiber-Reinforced Green Polymer Composites

Present work is concerned with the evaluation of the mechanical properties of compression molded Hibiscus sabdariffa (HS) fibre-reinforced Urea-Formaldehyde (UF) matrix based green polymer composites. Reinforcing of the Urea-Formaldehyde (UF) resin with Hibiscus sabdariffa (HS) fibre was accomplished in the form of short fibre (3 mm). It has been observed that mechanical properties of UF matrix increases with fibre loading and then decreases for higher loading (beyond 30%). Morphological and thermal studies of the matrix, fibre and short fibre-reinforced (SF-Rnf) green composites have also been carried out.     

Adhesion Improvement of Bio-Based Epoxy in Environmentally Friendly and High-Performance Natural Fiber-Reinforced Composites

Developing robust bio-based epoxy against petroleum-derived epoxy is necessary for environmentally friendly and high-performance natural fiber-reinforced composites. A bio-based vanillin epoxy (VE) is synthesized from the lignin-derived vanillin, and a thermoset resin is prepared after mixing it with a 4,4′-diaminodiphenyl methane (DDM) hardener. Further, it is infused in high-cellulose-containing alkali-treated jute fiber (TJF) mats through a simple approach to enhance the adhesion between the VE-DDM and TJF. Bio-based VE-DDM resin shows better compatibility with TJF than petroleum-derived bisphenol A diglycidyl ether (DGEBA) epoxy. The bio-based VE-DDM/TJF composite demonstrates the T_gis ≈165 °C, tensile strength is ≈83.12 ± 3.80 MPa, and Young's modulus is ≈2.86 ± 0.10 GPa with excellent flexural strength (138.72 ± 3.81 MPa) and flexural modulus (8.01 ± 0.11 GPa). It also shows merits regarding hydrophobicity, reduced water absorption ability, durability, and chemical resistance in an acidic medium. The natural fiber-reinforced VE composites pave the way to produce environmentally friendly and high-performance composites for structural applications.     

聚丙烯/纳米CaCO3复合材料的拉伸性能

采用2种填料粒子表面处理方法[（表面活化（SI）和钛酸酯偶联剂处理（SII）]分别制备了纳米级CaCO3填充聚丙烯复合材料。应用万能材料试验机在室温下考察TCaCO3粒子表面处理和CaCO3含量对复合材料拉伸力学性能的影响。结果表明，随着纳米粒子CaCO3体积分数（φ）的增加，2种试样的弹性模量和拉伸强度有轻微的变化，而粒子表面处理的影响不太明显。当φ为0．5％时，SI的拉伸断裂强度达至最大，然后随着φ的增加呈非线性函数形式下降；除个别测量点外，SII的拉伸断裂强度基本上随着φ的增加呈非线性函数形式下降。在相同的条件下，SI的拉伸断裂强度高于SII，而断裂伸长率则相反。     

Thermal Properties of Organic-inorganic Hybrid Composites Based on Multi-Epoxy Silsesquioxane and Epoxy Resin

The multi-epoxy cubic silsesquioxane (SSQE) was successfully introduced into epoxy resin (EP) and formed the organic-inorganic EP-SSQE hybrids. The hybrids were cured by 4,4′-diaminodiphenylsulphone (DDS) and the Fourier transformation infrared (FTIR) spectra were used to monitor the cured reaction of the hybrid, and the results showed that the hybrids could be cured thoughtfully without influence the cubic silsesquioane structure. The thermal properties of the hybrid such as the heat distortion temperature (HDT), the glass transition temperature Tg and the thermal decomposing property were studied. The results showed that the hybrids had the higher thermal properties than that of the pure epoxy resin for the introducing of multi-epoxy cubic silsesquioxane.     

Mechanical Properties of Long Glass Fiber-Reinforced Polyolefin Composites

Mechanical properties and fracture morphology for long glass fiber-reinforced-polyolefin composites and their blends were investigated. The properties like tensile, flexural, and impact strength of the composites at low temperature increased considerably and elongation at break reduced visibly with increase of glass fiber contents. Impact strength at room temperature was an exception, and impact strength of the composites was higher than that of impact polypropylene copolymer. The results are caused by interaction of rubber phase and amorphous parts in impact polypropylene copolymer. Extraction or fracture for glass fiber in the composites consumed more impact energy, which means they have higher impact strength.     

制备工艺对亚麻增强热塑性复合材料拉伸力学性能的影响

将增强体亚麻纱线和基体丙纶复丝制成pp/亚麻包覆纱后,进行织造,织物用层合热压法制成复合材料.制备工艺中,包覆纱法对复合材料的拉伸强度最好;麻含量50%的复合材料的拉伸强度达到最佳;当纬纱密度相同时,随着经纱密度的增大经向的拉伸强力和拉伸弹性模量也随之增大,而纬向的却随之减小,当经纱密度相同时,随着纬纱密度的增大,经向的拉伸强力和拉伸弹性模量随之减小,纬向的随之增大.     

The Addition of Carbon Nanotube on the Tensile Properties of Carbon Fiber-Reinforced PEEK Composites

The main objective of this paper is to develop high strength resistance carbon fiber-reinforced polyether ether ketone (PEEK) composites with the addition of multiwall carbon nanotubes (MWCNT). These compounds were well mixed in a Haake batch mixer, and compounded polymers were fabricated into sheets of known thickness by compression moulding. Samples were tested for tensile properties with respect to different concentration of fillers. The tensile properties of these samples depend on filler aspect ratio. The tensile fracture surface has been examined using a scanning electron microscope (SEM). Photomicrographs of the worn surfaces revealed the effect of the addition of carbon nanotubes. Also, better interfacial adhesion between carbon and vinyl ester in carbon reinforced vinyl ester composite was observed.     

香蕉纤维的表面改性及其增强环氧树脂复合材料的性能研究

采用硅烷偶联剂(A-174)偶联、高锰酸钾接枝和乙酰化包覆等3种方法对香蕉纤维进行表面改性,制备了改性香蕉纤维增强环氧树脂复合材料,测试其拉伸、弯曲、压缩、冲击等力学性能。结果表明,偶联、接枝、包覆等表面改性均能明显改善香蕉纤维与基体树脂的相容性,提高复合材料的力学性能,其中偶联改性的效果最好。当改性香蕉纤维含量为10wt%时,与未改性的香蕉纤维比较,复合材料的拉伸强度、弯曲强度、压缩强度分别提高了1.8、1.0、2.6倍;随着纤维含量的增加,复合材料的力学性能明显提高。     

环氧树脂/玻璃布复合材料拉伸剪切性能研究

本文介绍了浸渍方法、浸渍参数、树脂粘度及层压板纤维体积含量对环氧树脂/玻璃布拉伸剪切性能的影响。     

Chemical Recycling of Carbon Fiber Reinforced Epoxy Composites Using Mild Conditions

The increased use of carbon fiber reinforced thermosets generates more waste and end-of-life products. However, an efficient recycling method for the expensive carbon fibers has not yet been developed. The selective decomposition of amine-cured epoxy resin under mild conditions is presented. A two-step method was investigated to decompose the epoxy resin. The optimum parameters were initially determined using a model compound. By analysis of the reaction products, a cleavage of the C–N bond according to the Cope elimination could be proven. Therefore, the Cope elimination is suggested as the main step of the decomposition of amine-cured epoxy resins in presence of hydrogen peroxide. By dissolving the resin, it is possible to recover resin-free fibers with unimpaired mechanical properties.     

异形有机短纤维增强环氧树脂复合材料拉伸性能的研究

本文考察了纤维形态对异形有机短纤维增强环氧树脂复合材料光弹性能和拉伸性能的影响。结果表明，与平直短纤维复合材料相比，在环氧基体中加入凸端或竹节状的聚酰胺短纤维，不仅可以改变复合材料中的应力分析，有利于纤维末端的应力传递，而且能够提高短纤维复合材料的拉伸强度。     

紫外老化对芳纶／环氧复合材料性能和结构的影响

通过紫外老化试验（温度（40±5）℃,湿度40％）,研究了芳纶、环氧及其复合材料的力学性能、玻璃化转变温度、失重随老化时间的变化,并用红外光谱分析了芳纶的结构变化。结果表明：经紫外老化后,芳纶／环氧的拉伸强度、失重率有明显的变化,芳纶结构和复合材料的玻璃化转变温度无明显的变化。     

碳纳米管/聚合物复合吸波材料性能研究

碳纳米管通过化学气相沉积工艺制备,碳纳米管直径10～30nm,纯度>90%。碳源为乙炔、铁/镍复合催化剂。加入适量的有机溶剂丙酮溶解环氧树脂,然后加入碳纳米管。分别高速搅拌和超声处理30min,加入固化剂乙二胺搅拌均匀,超声10min除去气体后,浇铸在铝板上制成吸波涂层。TEM检测碳纳米管。反射率扫频测量系统HP8757E标量网络分析仪检测吸波性能。碳纳米管和环氧树脂比例为1∶100时,3mm厚吸波层试样吸波峰出现在14 32GHz,吸波峰值R=-10 01dB,吸波频带宽度为2 16GHz(R<8dB)。厚度增加到9mm,在11GHz和17 83GHz出现双吸波峰,最大吸波峰出现在17 83GHz峰值R=-9 04dB,带宽约1GHz(R<8dB)。比例调整为5∶100时,波峰出现在7 91GHz,峰值加大到R=-13 89dB,带宽度达到3 19GHz(R<8dB)。     

环氧树脂多孔复合材料的制备及性能

以环氧树脂为基体、蓖麻油酸(RA)或二聚蓖麻油酸(DRA)改性的四乙烯五胺(TEPA)(RATEPA/DRATEPA)作为固化剂、水为致孔剂、釉粉为无机填料,通过树脂-水-填料悬浮乳液复合体系聚合法,在室温下合成了环氧树脂多孔材料,采用SEM、压汞仪、电子万能试验机、TGA对多孔材料的形貌、孔径分布、孔隙率、机械性能及热性能进行了表征和测试。结果表明:随着水相质量分数和填料粒径的增大,多孔材料的孔径和孔隙率增大,压缩强度减小;随着固化剂分子量的增大,多孔材料的孔径和孔隙率减小,压缩强度增大。当填料粒径为40μm,固化剂为RATEPA,m(水相)∶m(树脂相)=2∶1时,多孔材料的综合性能最佳,其最可几孔径为3.449μm,孔隙率为21.8%,压缩强度为26.89 MPa。TGA和DTG测试结果表明:环氧树脂多孔材料的热稳定良好,具有耐高温性能,可以在高温条件下应用。     

聚丙烯复合材料声学特性研究进展

针对聚丙烯复合材料的声学特性,对近年此类材料的研究工作进行了回顾。以增强材料种类为区分,重点综述了玻纤增强聚丙烯复合材料、天然纤维/聚丙烯复合材料和无机填料聚丙烯复合材料吸隔声性能的相关研究,归纳了目前所报道的吸声材料的相关机理,总结了影响吸声性能的主要因素以及不同材料对不同频率噪声源的应用效果。