沥青基碳纤维及其混杂纤维增强尼龙1010复合材料结构与性能的研究

本工作研究了通用型沥青基碳纤维、玻璃纤维及它们的混杂纤维增强尼龙1010复合材料的结构与性能,并与相应的聚丙烯腈基碳纤维及其混杂纤维复合材料的性能作了系统的比较.实验结果表明,随短纤维含量的增加,复合材料的模量和强度线性增加,当纤维含量达到一定临界值时,其强度有所下降.聚丙烯腈基碳纤维增强尼龙1010复合材料比相应的沥青基碳纤维复合材料具有较好的力学性能,但后者通过与高强度玻璃纤维混杂增强,可提高其力学性能.本工作还研究了这些复合材料的断裂特征和它们的混杂效应.      

混杂短纤维增强聚苯硫醚复合材料的老化研究Ⅰ.破坏行为研究

本文研究了经80℃热水老化4000小时和加速气候老化1200小时的短碳纤维与玻璃纤维混杂增强聚苯硫醚复合材料的力学性能变化,并对复合材料中的纤维长度分布进行了统计。研究表明,纤维长度减小主要发生在挤出造粒阶段,而且大多数纤维的长度小于临界长度。混杂纤维增强的聚苯硫醚复合材料的拉伸强度和弯曲强度与混杂纤维比例基本上是线性关系,而冲击强度与混杂纤维比的曲线呈现下凹的趋势。加速气候老化对PPS损害较热水老化明显。老化后的复合材料力学性能保留率与老化方式和纤维种类有关。弯曲性能受老化影响较小,而拉伸性能受影响较显著。热水老化对玻璃纤维含量高的复合材料影响较显著。     

水润滑条件下沥青基碳纤维及其混杂纤维增强尼龙1010复合材料摩擦磨损性能的研究

通过对几种复合材料在水润滑条件下摩擦磨损性能的研究,发现沥青基碳纤维和表面处理的玻璃纤维混杂增强尼龙1010复合材料具有综合的优良性能,界面粘结状况对玻璃纤维复合材料的摩擦磨损性能有很大的影响。     

原位固态缩聚尼龙1010与纤维复合材料的力学性能和破坏形态

本工作借助扫描电子显微镜(SEM)研究了尼龙1010盐与磷纤维(CF)、玻璃纤维(GF)和混杂纤维(HF)预先复合,然后进行原位固态缩聚制得的纤维/尼龙1010复合材料的各种力学破坏形态。实验结果表明:取决于所用纤维的特性,所得的尼龙1010复合材料具有不同的界面粘结。并面粘结的强弱对复合材料的抗拉、弯曲和剪切破坏有着明显的影响,复合材料的冲击强度则与所用纤维的韧性有着较大的关系。在两种纤维协同增强复合材料中,具有弱界面效应的纤维/树脂的破坏将是引起复合材料破坏的一个重要因素。用低聚体尼龙1010接枝在含有羧基官能团的聚乙烯弹性体上,可制得具有优良力学性能的增韧尼龙。     

混杂短纤维增强尼龙1010的工艺与性能

本工作采用挤出造粒与注射成型的工艺,研究了以短碳纤维和玻璃纤维混杂增强尼龙1010的机械性能、耐热性、摩擦磨损性能及其“混杂效应”.统计了纤维在挤出和注射过程中长度分布的变化.观察了纤维在注射试样中的取向以及纤维与基体的粘结情况.      

碳纤维增强尼龙1010的力学性能及其对摩擦磨损的影响

用碳纤维填充尼龙1010制备了碳纤维增强尼龙复合材料,并对碳纤维增强尼龙复合材料的力学性能和摩擦学性能进行了实验研究。力学实验结果表明:碳纤维增强使尼龙复合材料的拉伸强度、表面硬度增大,碳纤维增强尼龙材料的拉伸强度在20%碳纤维含量时达到最大值;碳纤维表面处理对尼龙复合材料的拉伸强度有很大影响,碳纤维表面氧化处理提高了碳纤维增强尼龙复合材料的拉伸强度。摩擦磨损实验表明:碳纤维增强尼龙复合材料的摩擦系数和磨损率与其拉伸强度和硬度有密切关系。随着拉伸强度和硬度的提高,尼龙复合材料摩擦系数和磨损率降低;摩擦系数和磨损率与拉伸强度具有反比关系,与材料硬度具有二次方程关系,与碳纤维填充量之间存在负指数变化规律。      

碳纤维-玻璃纤维层内混杂单向增强环氧树脂复合材料拉伸性能

采用不同混杂比的碳纤维-玻璃纤维层内经向混编单轴向织物制备了混杂纤维增强环氧树脂复合材料, 研究了不同混杂结构和不同混杂比的碳纤维-玻璃纤维/环氧树脂复合材料拉伸性能的变化及破坏形式。0°拉伸结果表明:同种混杂织物的不同混杂结构中, 碳纤维相对集中的完全对齐结构强度最高, 不同混杂比织物的完全对齐结构强度相当;碳纤维-玻璃纤维/环氧树脂复合材料的模量遵循混合定律。90°拉伸结果表明:纤维与树脂间的界面结合强度为碳纤维/树脂>玻璃纤维/树脂, 碳纤维-玻璃纤维/环氧树脂复合材料的强度、模量与材料厚度方向上界面的不同形式(单一或交替界面、碳纤维或玻璃纤维的分布位置等)有关, 与碳纤维的含量基本无关。      

纳米SiC和SiO2与玻璃纤维混杂填充PA6的力学性能及摩擦磨损性能

采用注塑成型法制备纳米SiC和SiO2与玻璃纤维混杂填充PA6尼龙复合材料,对PA6复合材料的力学性能和摩擦学性能进行了实验研究,采用扫描电子显微镜观察分析磨损表面形貌。结果表明：纳米SiC或SiO2与玻璃纤维混杂填料能使PA6尼龙复合材料的拉伸强度和表面硬度增大。纳米SiOz与玻璃纤维混杂填料能使复合材料耐磨损性提高,以5％SiO2与玻璃纤维混杂填充耐磨性最佳;而纳米SiC与玻璃纤维混杂填料导致复合材料的磨损量增大,纳米SiC或SiO2与玻璃纤维混杂填充PA6复合材料的摩擦系数都低于尼龙材料。     

混杂增强聚氨酯复合硬泡塑料的物理及力学性能

研究纤维与颗粒混杂增强聚氨酯复合硬泡塑料的物理及力学性能,着重分析增强剂SiO₂颗粒和玻璃纤维含量以及纤维长度对其性能的影响。结果表明,SiO₂含量为20 wt％,玻璃纤维含量为7.8 wt％时,试样的拉伸强度达到最佳值。此外,还比较了玻璃纤维、尼龙66纤维和PAN基碳纤维的增强效果。结果表明,3 wt%~5 wt％含量碳纤维增强的聚氨酯复合硬泡塑料拉伸强度最佳。     

聚丙烯/热致液晶聚合物/玻璃纤维混杂复合材料 Ⅱ: 混杂复合材料的静态及动态力学性能

对具有良好液晶聚合物微纤结构的聚丙烯/热致液晶聚合物/玻璃纤维 (PP/TLCP/GF) 混杂复合材料,使用静态拉伸和动态力学分析 (DMA) 的方法研究了材料的力学性能。拉伸实验结果表明,混杂复合材料的拉伸强度和模量随着PP和TLCP挤出后的牵伸速率增大而上升,并且含有增容剂PP-g-MAH的体系,力学性能更优异。DMA测试结果表明,混杂复合材料的动态模量E'随着体系中玻纤的含量增加而增大;当体系中加入增容剂后,复合材料的刚性得到进一步提高。但无论是否使用了增容剂PP-g-MAH,当体系中玻纤含量高于20%后,模量随玻纤含量增大的趋势变缓。当体系中增强相的含量增加,以及加入增容剂使增强相与基体的界面粘结得到改善后,PP基体的损耗因子 (tanδ) 峰值都有一定的减小。      

Special manufacturing and characteristics of basalt fiber reinforced hybrid polypropylene composites: Mechanical properties and acoustic emission study

Basalt fiber reinforced, polypropylene matrix hybrid composites were manufactured in the process of carding, needle-punching and pressing. Hemp, glass and carbon fibers were applied besides basalt fiber in these composites. In order to achieve a sufficient interfacial adhesion, the fibers were treated with the reaction mixture of maleic acid anhydride and sunflower oil. The hybrid effect in these composites was examined as a function of fiber content and fiber combination. The strength properties of hybrid composites improved owing to surface treatment and this was proven by mechanical tests and microscopic analysis, as well. Acoustic emission methods revealed that there is a correlation between the physical parameters of sound waves that occurred during failure and the mechanical properties.     

Influence of hygrothermal environment on thermal and mechanical properties of carbon fiber/fiberglass hybrid composites

The absorption and diffusion of water in a carbon fiber/glass fiber hybrid composite was investigated. Water-sorption experiments, mechanical property tests and dynamic mechanical analysis (DMA) were performed after immersion in water at different temperatures for up to 32 weeks. The moisture uptake mechanism exhibited by the hybrid fiber system was determined to be more complex than the single fiber type. Weight-change profiles for the composites fitted the theoretical Fickian diffusion curve during the initial immersion time, but diverged substantially as time progressed. The shear properties and the glass transition temperature (T_g) were sensitive to the effects of hygrothermal environment, and values for both decreased with increasing water uptake. Microscopic inspection of water-soaked samples showed no cracking when the absorption was less than saturation. The thermal and mechanical properties were mostly retained (after drying), provided the moisture absorption did not exceed the saturation point.     

国产T800碳纤维用氰酸酯树脂开发及其复合材料性能

基于飞行器减重对耐高温结构复合材料的应用背景,为了拓展国产T800碳纤维增强氰酸酯复合材料体系的应用,通过对国产T800碳纤维表面上浆剂的分析,开展适于国产T800碳纤维的氰酸酯树脂基体配方设计,研究国产T800碳纤维/氰酸酯复合材料的力学性能和耐热性能,分析树脂基体对复合材料界面性能的影响。结果表明:国产T800碳纤维表面上浆剂中含有环氧基团。配方优化后的氰酸酯树脂与国产T800碳纤维复合后,复合材料的室温-湿态力学性能保持率大于74.8%,200℃力学性能保持率大于57%,玻璃化转变温度为226℃,具有优异的热机械性能和界面性能。     

Influence of fiber content on the mechanical and dynamic mechanical properties of glass/ramie polymer composites

The combination of glass and ramie fibers with a polyester matrix can produce a hybrid material that is competitive to all glass composites (e.g. those used in the automobile industry). In this work, glass and ramie fibers cut to 45 mm in length were used to produce hybrid polymer composites by resin transfer molding (RTM), aiming to evaluate their physical, mechanical and dynamic mechanical properties as a function of the relative glass–ramie volume fractions and the overall fiber content (10, 21 and 31 vol.%). Higher fiber content and higher ramie fiber fraction in the hybrid composites yielded lower weight composites, but higher water absorption in the composite. The mechanical properties (impact and interlaminar shear strength) of the composites were improved by using higher fiber content, and the composite with 31 vol.% of reinforcement yielded the lowest value for the reinforcement effectiveness coefficient C, as expected. Although the mechanical properties were improved for higher fiber content, the glass transition temperature did not vary significantly. Additionally, as found by analyzing the adhesion factor A, improved adhesion tended to occur for the composites with lower fiber content (10%) and higher ramie fiber fraction (0:100) and the results for the adhesion factor A did not correspond to those found by the analysis of the tan delta peak height.     

Analysis of effective elastic modulus for multiphased hybrid composites

Short fiber reinforced composites inherently have fiber length distribution (FLD) and fiber orientation distribution (FOD), which are important factors in determining mechanical properties of the composites. Since the internal structure has a direct effect on the mechanical properties of the composites, a Micro-CT was used to observe the three dimensional structure of fibers in the composites and to acquire FLD and FOD. It was successful to investigate FLD, FOD, and fiber orientation states and to predict the elastic modulus of the hybrid system. Since hybrid composites used in this study consist of three phases of particles, glass fibers, and matrix, theoretical hybrid modeling is required to consider reinforcing effects of both particles and glass fibers. Interaction between the particles and matrix was considered by using a perturbed stress–strain theory, the Tandon–Weng model. In addition, the laminating analogy approach (LAA) was used to predict the overall elastic modulus of the composite. Theoretical prediction of hybrid moduli indicated that there was a possibility of poor adhesion between glass fibers and matrix. The poor interfacial adhesion was confirmed by morphological experiments. This theoretical and experimental platform is expected to provide more insightful understanding on any kinds of multiphased hybrid composites.     

Carbon and glass hierarchical fibers: Influence of carbon nanotubes on tensile,flexural and impact properties of short fiber reinforced composites

Dense carbon nanotubes (CNTs) were grown uniformly on the surface of carbon fibers and glass fibers to create hierarchical fibers by use of floating catalyst chemical vapor deposition. Morphologies of the CNTs were investigated using scanning electronic microscope (SEM) and transmission electron microscope (TEM). Larger diameter dimension and distinct growing mechanism of nanotubes on glass fiber were revealed. Short carbon and glass fiber reinforced polypropylene composites were fabricated using the hierarchical fibers and compared with composites made using neat fibers. Tensile, flexural and impact properties of the composites were measured, which showed evident enhancement in all mechanical properties compared to neat short fiber composites. SEM micrographs of composite fracture surface demonstrated improved adhesion between CNT-coated fiber and the matrix. The enhanced mechanical properties of short fiber composites was attributed to the synergistic effects of CNTs in improving fiber–matrix interfacial properties as well as the CNTs acting as supplemental reinforcement in short fiber-composites.     

国产T700级碳纤维/BMI复合材料湿热性能

为研究国产碳纤维复合材料湿热性能,基于热压罐制备工艺,分别将国产T700级碳纤维和日本东丽T700S碳纤维与国产QY9611双马树脂进行匹配,从纤维表面物理/化学状态、吸湿曲线、吸湿后玻璃化转变温度、宏观力学性能等方面对2种复合材料开展湿热性能研究.结果表明:国产T700/BMI复合材料的饱和吸湿率为0.77%(35 d),T700S/BMI复合材料的饱和吸湿率为0.81%(19 d);71℃水浸168 h后,国产T700/BMI的玻璃化转变温度(T_g)下降10.3%(由252.1℃到226.2℃),T700S/BMI复合材料的玻璃化转变温度(T_g)下降8.7%(由256.6℃到234.3℃);150℃湿态环境下,国产T700/BMI复合材料90°拉伸强度与T700S/BMI基本相当,0°压缩强度较T700S/BMI高约17.9%,层间剪切强度较T700S/BMI高约9.3%,表明国产T700/BMI复合材料具有更优良的湿热力学性能.