黄麻纤维/环氧树脂复合材料的力学性能

探讨了黄麻/环氧树脂复合材料板的制作方法,并对不同质量分数与长度的黄麻纤维增强的板材进行了拉伸及弯曲性能测试,采用扫描电镜观察了拉伸断面的微观形貌.讨论了纤维质量分数与长度对复合材料拉伸强度、拉伸模量、弯曲强度和弯曲模量的影响.实验结果表明,加入黄麻纤维有利于提升环氧树脂的拉伸和弯曲,纤维质量分数与长度对复合材料力学性...     

丙烯酸甲酯接枝亚麻纤维及其在PVC/亚麻复合材料中的应用

以过硫酸钾（K2S2O8）为引发剂,制备了Flax-g—MA接枝物。研究了反应条件对接枝率和接枝效率的影响。结果表明,接枝率和接枝效率均随着单体用量的增加而增大,随引发剂用量的增加和反应温度的升高先增大后减小,随反应时间的延长而逐渐增大并趋于平衡。当反应温度为60℃,反应时间为4h,引发剂与单体质量比为0．12,单体与亚麻质量比为1．2时,接枝率和接枝效率最高。加入MA单体接枝改性的亚麻纤维后,有效地改善了PVC／亚麻复合材料的各项性能。     

丙烯酸甲酯接枝亚麻纤维及其在PVC/亚麻复合材料中的应用

以过硫酸钾(K2S2O8)为引发剂,制备了Flax-g-MA接枝物。研究了反应条件对接枝率和接枝效率的影响。结果表明,接枝率和接枝效率均随着单体用量的增加而增大,随引发剂用量的增加和反应温度的升高先增大后减小,随反应时间的延长而逐渐增大并趋于平衡。当反应温度为60℃,反应时间为4 h,引发剂与单体质量比为0.12,单体与亚麻质量比为1.2时,接枝率和接枝效率最高。加入MA单体接枝改性的亚麻纤维后,有效地改善了PVC/亚麻复合材料的各项性能。     

棉纤维增韧SiO2气凝胶复合材料的性能

以棉纤维作为增强体,二甲基二乙氧基硅烷(DMDES)和甲基三乙氧基硅烷(MTES)为共前驱体,采用溶胶-凝胶法结合冷冻干燥工艺制备了柔性的棉纤维/SiO2气凝胶复合材料.利用扫描电镜、压汞仪、万能试验机及热导系数测试仪等对材料进行表征分析,研究了棉纤维质量分数对复合材料的微观结构及力学性能的影响.结果表明,棉纤维的添加...     

玻纤/环氧树脂复合材料非线性粘弹性响应

为研究玻璃纤维增强环氧树脂基复合材料的非线性粘弹性响应,采用Schapery模型描述复合材料的非线性粘弹性,并在不同应力水平下分别对[90]₁₆横向试样和[±45]_4S面内剪切试样开展拉伸蠕变-回复试验. 根据试验观察到的残余粘塑性应变现象,在Schapery模型中引入粘塑性应变分量,提出一种基于解析法的非线性参数辨识方法,获得了Schapery非线性参数g₀, g₁, g₂和a_σ随应力的变化规律. 结果表明:当施加的横向拉伸应力大于横向拉伸强度的53%,面内剪切应力大于剪切强度的31%时,玻纤/环氧复合材料表现出明显的非线性粘弹性;横向上,非线性参数g_0T和g_2T与应力无关,g_1T随应力线性增加,a_σT随应力线性降低;面内剪切方向上,非线性参数g_0S和g_2S随应力呈指数增加,g_1S随应力线性增加,a_σS则随应力线性降低. 与传统的非线性参数辨识方法相比,所提出的参数辨识方法能方便准确地获取非线性参数随应力的变化规律.      

大豆蛋白复合纤维/亚麻混纺纱的活性染料染色性能

采用活性黄B-4RFN对大豆蛋白复合纤维/亚麻混纺纱进行染色,并研究其染色性能.在对染料固色率的影响因素(温度、碱剂用量、促染剂用量、时间)进行分析的基础上,利用正交试验确定了大豆蛋白复合纤维/亚麻混纺纱用活性黄B-4RFN进行染色的优化工艺,即染料用量2%owf.、纯碱15g/L、氯化钠50g/L,温度70℃,固色时间50 min.性能测试结果表明:活性黄B-4RFN上染大豆蛋白复合纤维/亚麻混纺纱的固色率为49.96%,且染色产品具有较高的牢度性能,可以满足一般染色产品对色牢度的要求,具有工艺可行性.     

溶剂法回收玻璃纤维/环氧复合材料的试验研究

为了解决现有化学回收法技术不适用于热固化体系的问题,采用溶剂法从玻璃纤维／环氧复合材料成功回收了玻璃纤维．在90℃的8mol／L分解液作用下,12h即可将复合材料中的环氧树脂基体分解为低分子含苯环有机物,回收到外观清洁的玻璃纤维．当分解温度为90℃,酸液浓度为8mol／L,投料比为6g：100mL时,回收纤维的单丝拉伸强度损失为5．2％．以分解时间、回收纤维强度损失为考查指标,利用正交实验法对分解条件进行优化,得到各因素的影响次序：浓度为最重要因素、温度次之、投料比影响最小．     

Computer simulated experiments on fracture toughness of particle-dispersed composites

0　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｈｅｔｅｒｏｇｅｎｅｏｕｓｑｕａｓｉ ｂｒｉｔｔｌｅａｇ ｇｒｅｇａｔｅｍａｔｅｒｉａｌｓｓｕｃｈａｓｃｏｎｃｒｅｔｅ ,ｒｏｃｋｓ ,ｃｅｒａｍｉｃｓ ,ａｎｄｖａｒｉｏｕｓｐａｒｔｉｃｌｅ ｄｉｓｐｅｒｓｅｄｏｒｆｉｂｅｒｒｅｉｎｆｏｒｃｅｄｃｏｍｐｏｓｉｔｅｓｅｘｐｅｒｉｅｎｃｅａｎｉｎｃｒｅａｓｅｉｎｆｒａｃｔｕｒｅｔｏｕｇｈｎｅｓｓａｓｔｈｅｉｒｓｉｚｅｉｎｃｒｅａｓｅｓ .Ａｎｅｓｓｅｎｔｉａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｏｆｑｕａｓ…     

Phase separation morphology and mode II interlaminar fracture toughness of bismaleimide laminates toughened by thermoplastics with triphenylphosphine oxide group

Toughness improvement of bismaleimide (BMI) resin is very important for its application in composite materials. Blending with thermoplastic polymer is usually used to increase the toughness of BMI matrix. In this work we prepared two thermoplastic polymers with polar triphenylphosphine oxide group in the polymer backbone. The synthesized thermoplastics with different polarities were investigated by several physicochemical methods. Then through scanning electronic microscopy we observed the phase separation morphology of BMI blends at different doping concentrations of thermoplastics. Additionally mode II interlaminar fracture toughness G _IIC of BMI laminates toughened with thermoplastics by ex-situ method was examined. The results showed that thermoplastic with strong polarity would bind tightly with BMI during curing and the phase-separation structure might be fixed at the primary stage; while secondary phase separation could happen in a relatively weak polarity system. It indicates that by regulating the polarity of thermoplastic, we may control the phase separation morphologies of blending system and the mechanical properties of composite.     

Influence of interfacial strength on the fracture toughness of glass-ceramic matrix composites

Nine kinds of glass-ceramic matrix composites with different compositions and interfacial strength (τ _s) were prepared. The influence of τ _s on the fracture toughness(K _1c) of composites was studied. It was discoved that, for the system no chemical reaction taking place at the interface, K _1c increased proportionally with τ _s increasing at the first stage, then decreased when τ _s reached a certain value. According to this result, a model of relationship between τ _s, thermal mismatch (Δα _r) and K _1c was built up. If a chemical reaction took place and a new phase was formed in the interface, the K _1c of composite was effected by the combination of τ _s, chemical bonding, radial interfacial stress and other factors. Project supported by the National Natural Science Foundation of China Synopsis of the first author Wang Lingsen, professor, born in 1938, current research field: special ceramic and ceramic matrix composite, etc.     

玻璃纤维增强环氧树脂单向复合材料力学性能分析

采用连续玻璃纤维与环氧树脂相复合,通过金属模压成型工艺,制备出单向玻璃纤维／环氧树脂复合材料。通过三点弯曲实验论证单向纤维对树脂基体的增强作用,从而研究不同纤维含量下复合材料的弹性模量、纵向拉伸强度、纵向压缩强度的变化趋势。结果表明：随着纤维含量的增加,复合材料的力学性能均增强,当纤维体积含量为50％时,其各项性能均较好,弹性模量为40GPa,纵向拉伸强度为1200MPa,纵向压缩模量为700MPa。此外,对复合材料的其他常用力学性能参数进行检测。     

聚丙烯纤维增强混凝土断裂韧度及软化本构曲线确定

对粗、细聚丙烯(Polypropylene, PP)纤维不同混掺情况下的混凝土切口梁试件进行三点弯曲试验,基于双K断裂理论探讨了不同尺寸PP纤维混掺方式对试件断裂韧度的影响及其破坏机理,并通过起裂、失稳、黏聚韧度3者之间的定量关系得到实测黏聚韧度、起裂韧度增量和桥接韧度。借鉴3种普通混凝土的双线性软化本构曲线计算得到理论黏聚韧度,并将其与实测黏聚韧度对比,确定适合于不同纤维掺入情况下PP纤维增强混凝土(Polypropylene fiber reinforced concrete, PFRC)的双线性软化本构曲线。研究结果表明,PFRC相对素混凝土有较高的起裂韧度、失稳韧度和断裂能;2或3种尺寸PP纤维混掺时,其桥接应力对桥接韧度的增强效果非常显著;3种尺寸PP纤维在裂缝扩展的不同阶段发挥桥接作用,体现了良好的混掺增强、增韧效应;徐世烺和Reinhardt改进的双线性软化本构曲线,取校正系数λ为6时,可较好地适用于PFRC。     

亚麻增强热塑性树脂基复合材料的开发

利用亚麻纤维的可纺性,与热塑性聚丙烯(Polypropylene,PP)纤维通过捻合形成PP包覆亚麻的混合纱结构,将所得混合纱线进行平纹布的织造,选取5层作为铺层数,在热压机上进行热压复合,制得亚麻/PP热塑性树脂基复合材料,并对其拉伸性能进行测试,得出其经向拉伸强度高于纬向,分别为69.34 MPa和61.76 MPa.     

Optimizing electrophoretic deposition conditions for enhancement in electrical conductivity of carbon fiber/carbon nanotube/epoxy hybrid composites

The effectiveness of optimizing electrical conductivity of carbon fiber/carbon nanotube (CNT)/epoxy hybrid composites via Taguchi method was demonstrated.CNTs were induced on carbon fabric by electrophoretic deposition (EPD) technique.The essential deposition parameters were identified as 1) the deposition time,2) the deposition voltage,3) the mass fraction of CNTs in suspension,and 4) the distance between the electrodes.An experimental design was then performed to establish the appropriate levels for each factor.An orthogonal array of L9 (34) was designed to conduct the experiments.Electrical conductivity results were collected as the response.The relative influences of design parameters on the response were discussed.Using the model,signal to noise (S/N) ratio and response characteristics for the optimized deposition parameter combination were predicted.The results show clearly that the optimum condition of electrophoretic deposition (EPD) process improves the electrical conductivity of carbon/epoxy hybrid composites.     

Optimizing electrophoretic deposition conditions for enhancement in electrical conductivity of carbon fiber/carbon nanotube/epoxy hybrid composites

The effectiveness of optimizing electrical conductivity of carbon fiber/carbon nanotube (CNT)/epoxy hybrid composites via Taguchi method was demonstrated.CNTs were induced on carbon fabric by electrophoretic deposition (EPD) technique.The essential deposition parameters were identified as 1) the deposition time,2) the deposition voltage,3) the mass fraction of CNTs in suspension,and 4) the distance between the electrodes.An experimental design was then performed to establish the appropriate levels for each factor.An orthogonal array of L9 (34) was designed to conduct the experiments.Electrical conductivity results were collected as the response.The relative influences of design parameters on the response were discussed.Using the model,signal to noise (S/N) ratio and response characteristics for the optimized deposition parameter combination were predicted.The results show clearly that the optimum condition of electrophoretic deposition (EPD) process improves the electrical conductivity of carbon/epoxy hybrid composites.     

Damping properties of fly ash/epoxy composites

An inexpensive fly ash (FA), which is from a waste product, was employed to prepare fly ash/epoxy composites. The purpose of this study is to characterize the contributions of matrix viscoelasticity, hollow structure characteristic (porosity), and filler/matrix interface friction to the high vibration damping capacity of such composites. The damping properties of the composites were investigated in the temperature range of -40 to 150°C and in the frequency range of 10 to 800 Hz by using a tension-compression mode. The results indicate that the peak value of damping loss factor (tanδ) for the fly ash/epoxy composites can reach 0.70-0.90 in test specification, and the attenuation of damping loss factor is inconspicuous with increasing frequency. In addition, scanning electron microscope (SEM) was used to observe the morphology of the fly ash as well as its distribution in the matrix, which will help to analyze the effect of fly ash on the damping properties of the fly ash/epoxy composites.     

亚麻/聚丙烯复合材料的制备及拉伸、顶破性能

以亚麻纤维作为增强纤维,以聚丙烯纤维作为树脂基体,通过模压成型工艺方法,制备了绿色环保型亚麻/聚丙烯复合材料,主要研究了纤维长度、模压温度及保温时间对复合材料拉伸性能及顶破性能的影响.结果表明:模压温度对复合材料性能的影响最显著;当纤维长度为5 mm、模压温度为180℃、保温时间为40 min时,复合材料的拉伸性能最优;在纤维长度为5 mm、模压温度为170℃、保温时间为40 min时,复合材料的耐顶破性能最优.     

超低温下层合板复合材料的短梁法层间剪切强度研究

采用三维有限元法对超低温下玻璃纤维强化树脂层合板的短梁法层间剪切强度进行了研究,通过与二维有限元解析结果的对比,分析了试验片三维形状对中性面上剪切应力分布的影响;通过三维有限元解析,阐明 了剪切领域内的剪切应力分布。数值解析结果表明,短梁剪切试验片的最大剪切应力并非在中性面上产生,靠近载荷点及支点附近产生较大的局部剪切应力;中性面上的剪切应力分布不均匀,但中性面上最大剪切应力均匀分布的范围较大;基于梁理论的表观层间剪切强度较中性面上的最大剪切应力值低,采用短梁剪切试验法时会产生较小的强度评价。     

玻璃纤维增强环氧树脂基复合材料的低温性能研究

对S玻璃纤维和E玻璃纤维增强环氧树脂基复合材料的常温和低温力学性能进行实验,结果表明：玻纤／环氧树脂单向复合材料力学性能随着纤维含量增加而增强,当纤维体积含量为50％时,复合材料具有较好的综合力学性能,且复合材料的强度随着温度的降低呈增加趋势。当温度降到76K时材料的强度达到最高值,S玻纤／环氧复合材料的拉伸强度最高值可达2．1GPa;E玻纤／环氧复合材料的最大拉伸强度也达到1．4GPa。其原因是由于低温下玻璃纤维的横向收缩比树脂基体小,界面摩擦力得到增强,从而获得高的界面粘接强度。     

亚麻纤维毡/不饱和聚酯树脂复合材料成型工艺研究

采用真空辅助树脂传递模塑法(VARTM)制取了亚麻纤维毡增强不饱和聚酯树脂复合材料，研究其成型工艺，分析了在成型过程中的树脂导入方法和树脂流动性，通过大量试验找出一种较为合适的树脂注入方式，制备出了性能良好的复合材料板材．