Expanded graphite nanoplatelets as coupling agents in glass fiber reinforced polypropylene composites

The interfacial adhesion between E-glass fibers and various types of nanomodified polypropylene (PP) matrices have been investigated on single-fiber model composites. In particular, an evaluation of the fiber–matrix interfacial shear strength was performed by the fragmentation tests on model composites prepared by using PP matrices containing various amounts (up to 7 wt%) of expanded graphite nanoplatelets (xGnP).The presence of xGnP in the polymer matrix resulted in a remarkable increase of the interfacial shear strength values (up to a factor of about 6 for a 7 wt% content of xGnP) if compared to neat PP. Moreover, wettability measurements in various liquids evidenced that the work of adhesion of the polymer matrix with respect to glass fiber, was improved by the presence of xGnP.     

Effect of fiber array on damping behaviors of fiber composites

This study aims to investigate the fiber array effect on modal damping behaviors of fiber composites. Three different fiber arrays, i.e., square edge packing (SEP), square diagonal packing (SDP), and hexagonal packing (HP), were considered to represent the microstructures of the unidirectional composites. Repeating unit cells (RUCs) suitable for describing the characteristics of the microstructure were adopted in the generalized method of cell (GMC) micromechanical analysis. The energy dissipation concept was then employed to calculate the specific damping capacities of composites in the material principal directions. The specific damping capacities obtained from micromechanical analysis were regarded as the equivalent damping properties homogenizing in the composites. In conjunction with the modal shapes of the composite structures determined from the finite element analysis, the specific damping capacity was extended to characterize the corresponding modal damping of the composite rods and plates. Both free–free and clamped-free boundary conditions were taken into account in the composite structures. Results indicated that the structures constructed from the composites with SDP fibers exhibit better damping behaviors than the other two cases.     

超声振动对玻纤增强聚丙烯复合材料注射成型特性的影响

为了研究超声振动对纤维增强复合材料注射成型特性的影响,利用自行开发的超声辅助可视化注射成型实验装置对不同玻纤(GF)含量的GF增强聚丙烯(PP)复合材料进行了超声外场作用下的可视化实验,观测分析了超声功率对复合熔体充填流动行为的影响。此外,通过对试样不同部位的金相观察,分析了超声功率对复合材料纤维取向的影响。结果表明:超声功率会对复合材料注射成型的充填流动行为及制品的纤维取向产生影响,而复合材料纤维含量对超声振动的效果也有直接影响。在纤维含量较低时,超声振动对基体材料微观形态的作用为影响复合材料充填流动性及纤维取向的主因;在纤维含量较高时,超声振动对纤维的作用为影响复合材料充填流动性及纤维取向的主因。研究结果为复合材料超声辅助成型技术的发展提供了依据。     

Fatigue failure in graphite fibre and glass fibre-polymer composites

Our studies have established that unidirectional graphite fibre composites show excellent fatigue resistance with only a 20 to 30% decrease in strength with cycling. Fatigue failures invariably occurred on the surfaces undergoing compression and were identified by scanning electron microscope studies as resulting from matrix failure adjacent to local fibre buckling failure zones. In contrast, glass fibre composites showed a much larger (70%) loss in strength under cyclic loading. At intermediate lives, failure occurred by the growth of matrix microcracks followed by delamination, while at long lives, the applied stress levels were below the microcrack initiation stress and behaviour was characterized by crack nucleation processes. These results have suggested a criterion for predicting high cycle fatigue strength which is based on the hypothesis that for failure to occur, the maximum applied effective cyclic strain in the composite must exceed a critical value which depends upon the fatigue response of the matrix material. The main assumption is that localized fatigue failures in the matrix are the predominant contributions to the ultimate fatigue failure of the composite.     

玻璃纤维/聚丙烯复合材料界面研究

采用γ射线预辐照固相接枝和偶联剂分别对聚丙稀粉粒 (PP)和玻璃纤维 (GF)进行表面改性 .研究接枝PP在基体中的含量、玻璃纤维经偶联剂处理对复合材料层间剪切强度 (ILSS)、拉伸强度的影响 .通过SEM对复合材料的拉伸断口进行了分析 .     

Non-destructive characterization of fibre-matrix adhesion in composites by vibration damping

Adhesion at the fibre-matrix interface in fibre-reinforced composites plays an important role in controlling the mechanical properties and overall performance of composites. Among the many available tests applicable to the composite interfaces, the vibration damping technique has the advantages of being non-destructive as well as highly sensitive. An optical system was set up to measure the damping tangent delta of a cantilever beam, and the damping data in glass fibre-reinforced epoxy-resin composites were correlated with transverse tensile strength which are also a qualitative measurement of adhesion at the fibre-matrix interface. Four different composite systems containing three different glass fibre surface treatments were tested and compared. Our experimental results showed an inverse relationship between damping contributed by the interface and composite transverse tensile strength. This revised version was published online in November 2006 with corrections to the Cover Date.     

臭氧处理对石墨纤维复合材料性能的影响

为改善石墨纤维和氰酸酯树脂间的界面性能,利用臭氧处理技术对石墨纤维进行表面处理,并采用AFM、XPS和IR对处理前后的石墨纤维表面形貌和组成进行了分析,研究了臭氧处理对石墨纤维/氰酸酯复合材料层间剪切强度和弯曲强度的影响.实验结果表明:臭氧处理提高了碳纤维表面活性,从而改善了石墨纤维/氰酸酯复合材料的界面粘结性能,进而改善了复合材料的界面和力学性能.     

Improved mechanical property of foam glass composites toughened by glass fiber

The mechanically improved foam glass composite toughened by glass fiber was prepared by sintering technique, using waste sodium-calcium silicon flat glass powder as main raw materials. In this study, the preparation and properties of the samples were characterized by differential thermal analysis (DTA), field-emission scanning electron microscopy (FESEM) and mechanical property test. The specific strength of the composite was defined for the first time, and applied into the investigation of mechanical property. The results show that the specific improved bending strength of 10.45-22.26 MPa/(g cm^− 3), and the specific compressive strength of 30.45-34.34 MPa/(g cm^− 3) can be displayed when sintered at 790-815 °C with the addition of 5-25 wt.% glass fiber. Good correlations between the microstructure (in particular the fiber distribution), the high specific strength and the high modulus of elasticity of glass fibers.     

玻璃纤维增强聚丙烯复合材料制孔损伤

为抑制玻璃纤维增强聚丙烯复合材料（GF/PP）制孔损伤并提高其制孔效率,本文通过钻削实验获得多种进给速度下的GF/PP复合材料钻削轴向力和出口温度,使用高速摄影设备对刀具钻出过程进行在线观测,研究出口材料去除过程及其损伤成因,分析进给速度对GF/PP复合材料制孔损伤的影响规律。结果表明：GF/PP复合材料的钻削出口温度在低速进给时显著升高,在高速进给时基本趋于稳定;出口撕裂是重要的出口损伤形式,成因是大片毛刺受副切削刃的撞击和撕挤,进给速度过高或过低均会加剧损伤; 0°毛刺在低速进给时较严重,入口撕裂在高速进给时较严重。     

Molecular characterization of glass fiber surface coatings for thermosetting polymer matrix/glass fiber composites

Model multi-component glass fiber sizings, with formulations based upon current patent disclosures, were prepared to model the full coating packages used in commercial glass fiber manufacture. The sizings consisted of silane coupling agent, film former, and emulsifying surfactant in water and were applied to glass fibers prepared directly from molten glass. Fibers were analyzed before and after acetone extraction. The analyses of the extract solutions, with the fiber analysis, were used to determine the quantity and quality of the physically and chemically adsorbed layers. It was found that all three species remain on the fiber after extraction and that both coupling agent and surfactant concentrations in the coatings are higher than in the applied sizing. The impact of these species on the polymer composite/glass fiber interphase is discussed.     

短玻纤增强丙烯腈-丁二烯-苯乙烯共聚物的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及短玻璃纤维(SGF)为原料, 以苯乙烯-马来酸酐共聚物(SMA)和环氧树脂(EP)为界面相容剂, 制备了SGF/SMA-EP-ABS复合材料。用扫描电镜(SEM)、 动态力学热分析(DMTA)等研究了界面相容剂对SGF增强ABS复合材料力学性能及界面粘结性能的影响。结果表明:加入SMA或EP, SGF增强ABS复合材料的力学性能明显提高; SMA与EP同时加入具有明显的协同效果, 使复合材料的性能更为优越。当SGF加入质量分数为30%时, SGF/SMA-EP-ABS复合材料的拉伸强度、 弯曲强度、 冲击强度较未添加界面相容剂时分别提高了56%、 42%、 79%。SEM和DMTA测试表明, 加入SMA和环氧树脂后, SGF与ABS基体之间的界面粘结性能得到很大改善。      

连续玻璃纤维和玻璃微珠共增强尼龙6复合材料的抗冲击性能

低速冲击是聚合物基复合材料在运输和服役过程中常见损伤方式,常造成复合材料结构损伤、性能降低、承载能力下降,影响使用。针对2D纤维增强聚合物基复合材料在冲击载荷作用下抗分层能力差的问题,本文采用熔融挤出结合热压成型法制备了二元和三元尼龙6(PA6)基复合材料,对比研究了连续玻璃纤维(GF)、玻璃微珠(GB)及两者共增强PA6基复合材料的摆锤冲击性能和落锤低速冲击响应。结果表明：(1) GF和GB能显著提高PA6的抗冲击性能,且GF的增强效果明显高于GB;(2) GB增强PA6基复合材料(GB/PA6)的冲击强度随GB加入量增大而先增大后降低,加入量为25wt%时冲击强度最大;冲击载荷作用下,25wt%GB/PA6的耗能机制除了界面脱粘和钉扎效应之外,还发现GB在PA6基体中的滑移耗能新机制;(3) GF和GB共增强PA6复合材料(GB-GF/PA6)中纤维起主要的增强作用,摆锤冲击实验和落锤冲击实验均证明存在协同增强效应;(4) GF和GB共增强的协同增强效应是由于共增强复合材料在冲击载荷作用下,抗Ⅱ型裂纹扩展能力提高,使复合材料抗分层能力得到强化;从而证明在基体中引入适量球形GB是提高...     

玻璃纤维增强铅网/橡胶阻尼复合材料研究

为了改善橡胶的力学性能和阻尼性能,以橡胶、纤维和铅为原料设计了玻璃纤维增强铅网/橡胶阻尼复合材料,研究了不同玻璃纤维增强铅网铺层数量的横向玻璃纤维增强铅网/橡胶复合材料力学性能和阻尼性能,分析了其阻尼机制.结果表明,复合材料具有比橡胶更高的力学性能和阻尼特性,其刚度随铅网铺层数量的增加而提高,而阻尼损耗因子与铺层数呈非线性关系.复合材料中存在材料变形耗能、界面耗能、摩擦耗能等多种阻尼损耗机制.     

嵌入式低温共固化高阻尼纤维/树脂基复合材料

通过正交试验新研制出一种可以与玻璃纤维/BA9913环氧树脂预浸料低温共固化的高阻尼黏弹性材料,提出使用四氢呋喃（THF）作为溶剂,将该高阻尼材料制成黏弹性材料溶液。采用双面刷涂工艺,将玻璃纤维/BA9913环氧树脂复合材料制成带阻尼薄膜的预浸料,按照设计的铺层根据热压罐固化工艺制成嵌入式低温共固化高阻尼复合材料试件。模态试验和层间剪切试验验证了本文所提出制作工艺和黏弹性材料组分的有效性,试件一阶模态损耗因子可达7.2%。为嵌入式低温共固化高阻尼复合材料的广泛使用奠定了基础。      

纤维角度对变角度层合板减振性能的影响

自动铺丝技术可以实现复杂曲率曲线铺放,可极大提高角度设计的自由度。本文以改善复合材料层合板动态特性为目的,对变角度层合板的减振性能进行了研究分析。首先对不同角度变化变角度层合板进行自由衰减试验,研究了纤维角度变化与变角度层合板阻尼比的关系。然后对含相应角度变角度夹层板进行随机试验,研究了层合板随机激励条件下的振动响应,并采用共振峰处传递函数(Transition function,TF)和拾振点加速度总均方根(Root mean square,RMS)两种指标评价减振效果。结果表明:层合板阻尼比在纤维变化角度为±<45|60>时最大,纤维变化角度为±<73|88>时最小。基于RMS减振评价指标,±<45|60>夹层板较传统直线板减振性能提高27.13%;基于共振峰TF减振评价指标,纤维角度变化对不同共振峰减振效果规律差异明显。研究表明,变角度层合板减振性能明显优于传统直线层合板,相关实验结果将对变角度层合板减振设计及优化提供一定的参考意义。      

玻璃钢约束阻尼复合结构的阻尼特性

以玻璃纤维增强树脂作为约束层主要材料、丁腈橡胶为阻尼层、钢板为基板制备约束阻尼复合结构, 运用动态黏弹谱仪和悬臂梁共振法, 研究温度、约束层刚度和阻尼层结构对约束阻尼复合结构减振效果的影响。结果表明:自由阻尼复合板的最大阻尼范围落在阻尼层的玻璃化转变区;玻璃钢约束层能将复合结构的阻尼拓展至阻尼层的高弹态区域, 增加阻尼层厚度可以提高约束复合板的阻尼性能;提高孔隙率同样有利于约束复合板阻尼性能提升;铝板约束层提升作用尤为显著, 然而在海洋环境、干湿交替等强腐蚀场合中, 铝板极易腐蚀而丧失约束功能, 因此在这类特殊场合下耐腐蚀的玻璃钢具有优势。      

Mechanical properties of palmyra/glass fiber hybrid composites

Use of eco friendly composites gains attraction due to its lightweight and moderate strength in the recent years. Palmyra fiber is a natural fiber obtained from Palmyra (Borassus flabellifer) tree. Mechanical properties of randomly mixed short fiber composites are studied and optimum fiber length and wt% are estimated. This paper deals with the properties of (randomly mixed) palmyra fiber, glass fiber hybrid composites. Two types of specimens are prepared, one by mixing the palmyra and glass fiber and the other by sandwiching palmyra fiber between the glass fiber mats. Composite plates are prepared for different palmyra/glass fiber weight ratio. Rooflite resin is used as matrix. Tensile, impact, shear and bending properties are studied. The mechanical properties of the composites are improved due to the addition of glass fiber along with palmyra fiber in the matrix. The glass fiber skin–palmyra fiber core construction exhibits better mechanical properties than dispersed construction. Moisture absorption studies are conducted and the results are presented as a function of square root of time. Addition of glass fiber with palmyra fiber in the matrix decreases the moisture absorption of the composites.     

玻纤增强复合材料抗爆震性能研究

采用炸药柱近似模拟平面波发生器 ,利用传感器对 3种玻纤复合材料的抗爆震性能进行了研究。试验结果表明 ,玻纤复合材料对爆炸冲击波衰减作用的大小与基体材料的阻尼特性有关。基体材料的阻尼性能越好 ,复合材料对冲击波的衰减作用也就越好。     

Investigation of the dynamic Young's modulus and vibration damping for cryomilled NiAl–AlN composites

Measurements were made of the dynamic Young's modulus (stiffness) and damping for NiAl specimens containing varying amounts of aluminium nitride and prepared by cryomilling. Five specimens of NiAl–AlN were measured at room temperature, each specimen having a different percentage of AlN in the range 1%–30%. Further measurements were made on the 1% and 30% AlN specimens for the temperature range 22–495°C. At room temperature, the Young's modulus of the NiAl–AlN specimens decreased linearly with increasing percentage of AlN. The temperature dependence of Young's modulus for the 1% and 30% AlN specimens was found to be linear. These results were compared with those of typical nickel-based superalloys for a similar temperature range. The damping for all of the NiAl–AlN specimens was of the order of that for other intermetallic compounds (10-3–10-4). The study opened up the possibility of NiAl–AlN being a less-expensive and more easily produced alternative to nickel-based superalloys for high-temperature, high-stiffness applications. © 1998 Kluwer Academic Publishers