玻纤增强热塑性复合材料界面结晶行为研究进展

综述了玻纤增强热塑性复合材料界面结晶的形成机理及其研究进展,从结晶动力学的角度深入阐述了不同晶型(α晶和β晶)横晶的形成条件和结构特点,全面归纳了横晶形成的各种影响因素及研究者的不同观点,详细讨论了横晶对玻纤增强热塑性复合材料力学性能的影响,展望了热塑性复合材料界面结晶行为的研究动态。     

碳纤维表面阴离子接枝尼龙6对CF/PA6复合材料界面形态的影响

研究了碳纤维(CF)表面阴离于接技尼龙6(PA6)对CF/PA 6复合材料界面形态的影响,考察了纤维表面、结晶温度对CF/PA 6复合材料界面形成横晶的影响.结果表明在低于初始结晶温度至接近熔点范围内,PA6在未接枝与接枝CF表面均可以形成横晶,结晶温度低形成的横晶不致密、不完整,纤维诱发横晶的能力小,结晶温度高形成的横晶完整而致密,纤维诱发横晶的能力大.在相对较低的结晶温度下,接枝CF比未接枝CF具有较高的诱发横晶能力,同时诱发的横晶致密度高及完整性好.     

纤维增强等规聚丙烯复合材料的界面β横晶研究进展

综述了近年来纤维增强等规聚丙烯复合材料界面β横晶的研究进展。重点介绍了几种可获得界面β横晶的方法。从结晶动力学的角度阐述了界面β横晶的形成条件及结构特点,并对影响界面β横晶形成的因素进行了分析。     

玻璃纤维增强聚丙烯复合材料的界面结晶行为

在纤维增强热塑性聚合物复合材料的成型过程中,纤维的表面可能对基体产生结晶成核效应,形成界面横晶,横晶的出现对材料界面的应力传递行为,破坏行为产生很大的影响。本文综述了玻璃纤维增强聚丙烯复合材料结晶情况,界面横晶的产生,横晶对材料力学性能的影响以及控制方法。     

半晶聚合物基复合材料的界面结晶行为

半晶聚合物基复合材料界面处常形成横晶与杂化串晶。综述了近年来关于界面结晶的研究进展。重点分析了横晶与杂化串晶的制备方法及形成机制,并详细讨论了界面结晶的形成对复合材料力学性能的影响。最后对未来的研究方向进行展望。     

玻璃纤维增强聚丙烯复合材料的界面结晶行为

在纤维增强热塑性聚合物材料的成型过程中,纤维的表面可能对基体产生结晶成核效应,形成界面横晶,横晶的出现对材料界面的应力传递行为、破坏行为产生很大的影响。本文介绍了玻璃纤维增强聚丙烯复合材料结晶情况,界面横晶的产生,横晶对材料力学性能的影响以及控制方法     

iPP/GF复合材料界面晶型对界面剪切强度的影响

通过剪切诱导熔体结晶方法,制备了具有α球晶、α横晶和β横晶的等规聚丙烯(iPP)/玻璃纤维(GF)单纤维复合材料。利用单纤维断裂试验方法,测试了iPP/GF单纤维复合材料的界面剪切强度(IFSS),探讨了界面晶型对IFSS的影响。结果表明,界面为α球晶、α横晶和β横晶试样的IFSS依次增大。这说明界面结晶晶型对IFSS有显著的影响。     

PEEK/CF复合材料中PEEK结晶行为研究进展

对聚醚醚酮（PEEK）/碳纤维（CF）复合材料界面结晶研究现状进行综述,分析PEEK在复合过程中的结晶形态演变,总结影响PEEK在CF表面形成横晶结构的关键因素。PEEK横晶结构的生成与CF和PEEK的微观结构匹配性、导热性能匹配性,以及复合材料的热处理条件密切相关。诱导PEEK在CF表面形成横晶结构有助于提高二者的界面结合强度,进而提升复合材料的拉伸强度和杨氏模量。     

POE-g-Si对PP/木粉复合材料结构和性能的影响

以硅烷接枝乙烯-1-辛烯共聚物(POE-g-Si)为增容剂,制备了聚丙烯(PP)/POE-g-Si/木粉复合材料。研究了POE-g-Si对PP/木粉复合材料的晶态结构、界面相容性、动态力学性能及力学性能的影响。加入POE-g-Si有效改善了复合材料的界面相容性;PP中β晶型消失,结晶度由71.50%降至61.91%,木粉与基体界面处出现横晶;α,β转变峰均增强;复合材料拉伸强度、抗冲击性能均明显提高。     

半结晶性聚合物/碳纳米管复合材料结晶行为的研究

介绍了碳纳米管对半结晶性聚合物结晶行为的影响:提高结晶动力学、改变晶型及影响晶体形貌等。针对碳纳米管和半结晶性聚合物之间的界面相互作用,综述了两者之间的界面结晶问题,包括外延结晶、纳米杂化串晶、横晶的形成,以及一些相应的形成机制。最后对半结晶性聚合物/碳纳米管复合材料结晶行为的研究进行了展望。     

Electrophoretic Deposition Forming of Nickel-Coated-Carbon-Fiber-Reinforced Borosilicate-Glass-Matrix Composites

The present paper introduces a novel processing technique that involves in situ electrophoretic deposition (EPD), followed by pressureless sintering, to produce dense, defect-minimized, carbon-fiber-reinforced borosilicate-glass-matrix composites with a nickel interface. The process relies on the deposition of submicrometer-sized, colloidal charged particles onto unidirectionally aligned nickel-coated carbon fibers. The preparation and characterization of a kinetically stable nanosized borosilicate sol suitable for EPD are described. The most-important EPD processing parameters in the formation of dense, fully infiltrated, green-body compacts are described, and issues that concern the infiltration of very tight carbon fiber preforms are discussed and effectively solved. Using the crack-path-propagation test, the metallic nickel interface is determined to be very effective to improve the composite mechanical performance, in terms of the nonbrittle fracture behavior. Catastrophic crack growth is prevented by such mechanisms as constrained plastic deformation of the interface and fiber debonding and pullout. The proposed processing technique has great potential to fabricate defect-minimized and damage-tolerant fiber-reinforced brittle-matrix composites with a ductile interface. Overall, this new approach offers a cost-effective and short-time processing route for the fabrication of continuous-fiber-reinforced ceramic-matrix composites.     

In Situ Reacted Rare-Earth Hexaaluminate Interphases

A novel in situ reaction between a ceria-doped zirconia interphase coating on Saphikon fibers and an outer alumina coating has resulted in the formation of oriented hexaaluminate platelets which can act as a low fracture energy interface barrier for crack deflection in oxide-oxide ceramic-matrix composites (CMCs). The reaction proceeds only in reducing environments where the reduction of the cerium and zirconium ions to their 3+ valent state causes a destabilization phenomenon consistent with previously reported findings. The diffusion of the cerium from the zirconia into solid solution with the alumina can stabilize the layered hexaaluminate structure. Preferred orientational growth of the hexaaluminate parallel to the coating interface was observed which is the required orientation for enhanced debonding at the fiber/matrix interface in long-fiber-reinforced CMCs.     

Interfacial agents for multiphase polymer systems: Recent advances

The rapid growth in the use of multiphase polymer systems (blends and composites) is undoubtedly related to the availability of methods of controlling the physical and chemical interactions at the interface. Compounds acting as interfacial agents are commonly known as “compatibilizers” in blends, or “coupling agents” in composites; their function is to promote adhesion and enhance overall properties. This paper is a review of recent advances in the use of these compounds in immiscible polymer blends and thermoplastic composites. Polymeric compatibilizers are classified according to their method of addition (in situformation vs. separate addition) and reactivity. Reactive low molecular weight compounds are also listed and their various coupling mechanisms are discussed. It is demonstrated that common routes to enhanced adhesion exist for some types of blends and composites. For example, reactive graft copolymers and certain crosslinklng agents are equally effective as adhesion promoters in blends and composites containing a polyolefin phase.     

Tailoring Carbon Fiber/Carbon Nanotubes Interface to Optimize Mechanical Properties of Cf‐CNTs/SiC Composites

C_f/SiC composites were fabricated using fiber coatings including CNTs and matrix infiltration using the polymer impregnation and pyrolysis process. Interface between fiber and CNTs (CF/CNTs) was tailored to optimize mechanical properties of hybrid composites. The tailored interphases, such as Pyrocarbon (PyC) and PyC/SiC, protect fibers from degradation during the growth of CNTs successfully. Hybrid composites with well‐tailored CF/CNTs interface displayed significantly increased mechanical strength (352 ± 21 MPa) compared with that (34 ± 3 MPa) of composites reinforced with CNTs, which grown on carbon fibers directly. The interfacial bonding strength of hybrid composites was improved and optimized by tailoring the CF/CNTs interface. Interfacial failure modes were studied, and a firm interface bonding at the joint where CNTs grown was observed.     

Fracture morphology of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

The morphologies of the fracture surface under impact and flexural testing of Mg(OH)₂/Polypropylene (PP) composites and their modified composites were investigated by scanning electron microscopy. Experimental results indicated that addition of functionalized polypropylene (FPP) and acrylic acid (AA) and the formation of in situ FPP changed the fracture morphologies of Mg(OH)₂/PP composites. We believe that addition of these modifiers improved the interfacial interaction and enhanced the interface adhesion between the particle and the matrix in Mg(OH)₂/PP composites. The degree of improvement was more significant in Mg(OH)₂/PP composites modified by the formation of in situ FPP. At low Mg(OH)₂ content, 2 phr AA exhibited a marked effect, but at high Mg(OH)₂ content, 4 phr AA afforded good effect. Due to the improved interface adhesion by interface interactions the fracture mechanism transformed from interface debonded fracture into a matrix fracture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2148–2159, 2003     

Microstructure and damage evolution of SiCf/PyC/SiC and SiCf/BN/SiC mini-composites: A synchrotron X-ray computed microtomography study

SiC_f/PyC/SiC and SiC_f/BN/SiC mini-composites comprising single tow SiC fibre-reinforced SiC with chemical vapor deposited PyC or BN interface layers are fabricated. The microstructure evolutions of the mini-composite samples as the oxidation temperature increases (oxidation at 1000, 1200, 1400, and 1600?°C in air for 2?h) are observed by scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction characterization methods. The damage evolution for each component of the as-fabricated SiC_f/SiC composites (SiC fibre, PyC/BN interface, SiC matrix, and mesophase) is mapped as a three-dimensional (3D) image and quantified with X-ray computed tomography. The mechanical performance of the composites is investigated via tensile tests.The results reveal that tensile failure occurs after the delamination and fibre pull-out in the SiC_f/PyC/SiC composites due to the volatilization of the PyC interface at high temperatures in the air environment. Meanwhile, the gaps between the fibres and matrix lead to rapid oxidation and crack propagation from the SiC matrix to SiC fibre, resulting in the failure of the SiC_f/PyC/SiC composites as the oxidation temperature increases to 1600?°C. On the other hand, the oxidation products of B₂O₃ molten compounds (reacted from the BN interface) fill up the fracture, cracks, and voids in the SiC matrix, providing excellent strength retention at elevated oxidation temperatures. Moreover, under the protection of B₂O₃, the SiC_f/BN/SiC mini-composites show a nearly intact microstructure of the SiC fibre, a low void growth rate from the matrix to fibre, and inhibition of new void formation and the SiO₂ grain growth from room to high temperatures. This work provides guidance for predicting the service life of SiC_f/PyC/SiC and SiC_f/BN/SiC composite materials, and is fundamental for establishing multiscale damage models on a local scale.     

Preparation of Polymethylmethacrylate-Reinforced Functionally Graded Hydroxyapatite Composites

A functionally graded hybridization approach has been used in the formation of polymer-ceramic composites of polymethylmethacrylate (PMMA) and hydroxyapatite (HAp). HAp was successfully reinforced by sedimentary HAp distributions on a PMMA matrix using a centrifuge to avoid stress convergence on the interface. The stress-strain curves of the functionally graded PMMA-HAp composite showed sufficient mechanical strength with reduced brittleness. Scanning electron micrographs also showed evidence of exposed HAp on the surface of the composites.     

复合体系中微观相界面对材料性能的影响——Ⅲ.非反应性助偶联剂对HDPE/CaCO_3复合体系的增韧效果

将改性石蜡(NR)作为非反应性助偶联剂,考察了其对高密度聚乙烯/碳酸钙(HDPE/CaCO_3)复合体系中微观相界面的作用及其对体系物理机械性能的影响。结果表明:由于新的第3相界面的形成,一方面改善了CaCO_3与基体树脂之间的界面粘结状态,另一方面增加了CaCO_3与基体树脂之间的力学作用层厚度,促进了CaCO_3对HDPE树脂的增韧作用,使冲击强度得到大幅度的提高。NR的改性作用与基体树脂的韧性、偶联剂种类及其用量水平等有关。体系的缺口冲击强度因NR的加入有明显提高,对韧性较差的基体有明显的增韧效果。对拉伸强度影响较小,对弯曲强度略下降。若基体树脂韧性较好,NR可使HDPE/CaCO_3复合体系保持较好的综合物理性能。     

Improved interfacial adhesion in carbon fiber/poly (ether ether ketone) composites with the sulfonated poly (ether ether ketone) sizing treatment

A water-soluble sulfonated poly (ether ether ketone) (SPEEK) sizing agent is prepared and applied to improve the interfacial adhesion of carbon fiber/poly (ether ether ketone) (CF/PEEK) composites. The surface morphology, surface roughness, surface chemistries, and surface free energy of SPEEK sized CF are obtained to understand the sizing effect. The results reveal the increased surface free energy and surface roughness of SPEEK sized CF. In addition, a chemical reaction between the CF surface and sizing layer is proved based on the results of XPS, IR, and ¹H NMR. The interfacial structure of CF/PEEK composites is further ascertained by AFM and the appearance of gradient interface could be verified for SPEEK sized CF/PEEK composites. The formation of the gradient interface is due to the chemical reaction between the CF and sizing agent as well as the improved compatibility between the sized CF and matrix, which benefits the improvement of interfacial adhesion.