聚合物复合材料中的纳米杂化串晶研究

聚合物纳米复合材料界面结晶处常形成纳米杂化串晶(NHSK)。文章综述了近年来纳米杂化串晶结构的研究进展,介绍了NHSK形成的方法和影响NHSK形成和生长的因素,并对NHSK的形成机理进行了深入探究。最后,介绍了NHSK的应用,并对其发展趋势做了展望。     

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。     

聚合物基复合材料界面横晶的分析

对横晶形成的机制进行分析,并将横晶对材料的一些影响作了相应的剖析。     

聚合物基复合材料界面横晶分析

对横晶的形成的机理通过相应文献作出了分析,并对横晶对材料的一些影响作了相应的剖析。     

流动诱导半结晶聚合物中柱晶的研究概述

介绍了不同工艺参数、不同成型装置下的柱晶结构,分析了材料种类（分子结构）、工艺条件对柱晶形成的影响,结合已有研究成果,提出了流动诱导柱晶研究中有待进一步完善的若干问题。     

聚合物基纳米复合材料的界面

对聚合物基纳米复合材料进行了简单的归类，综述了各种聚合物基纳米复合材料的界面研究进展。具体介绍了改善聚合物一热液晶聚合物(TLCP)纳米复合材料界面相容性的方法及TLCP的增韧机理、无机纳米粒子与聚合物界面相互作用对增强、增韧效果的影响及纳米粒子的增韧机理。并对纳米复合材料的界面研究提出了一些看法。     

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。     

聚合物纳米复合材料结晶行为研究综述

综述了国内外聚合物纳米复合材料结晶行为的最新研究进展。其聚合物基体主要包括有聚丙烯、尼龙、聚苯乙烯、聚对苯二甲酸乙二醇酯和聚乙烯等；填充的纳米粒子主要有：CaCO3、有机蒙脱土、黏土和SiO2等。同时，总结了研究聚合物纳米复合材料结晶行为的理论模型。对聚合物纳米复合材料结晶行为的研究进行了展望。     

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     

碳纤维增强聚醚醚酮的非等温结晶行为与力学性能

利用聚酰亚胺(PI)作为碳纤维(CF)界面改性剂,制备了界面改性碳纤维增强聚醚醚酮(MCF/PEEK)复合材料。采用差示扫描量热仪(DSC)讨论了CF及其界面改性对PEEK非等温结晶行为的影响机制与作用规律,并基于莫志深法研究了MCF/PEEK的非等温结晶动力学;借助DSC和小角X射线散射仪(SAXS)表征不同降温速率下PEEK基体的结晶结构,采用万能试验机评价了MCF/PEEK的力学性能。结果发现:CF对PEEK的结晶有较为明显的异相成核促进作用,经过PI界面改性之后成核作用有所下降,但结晶行为仍较纯PEEK更容易发生,整体结晶速率更快;随冷却速率的增大,基体结晶度、片晶厚度与长周期均减小,MCF/PEEK的拉伸强度与模量也显著减小,层间断裂韧性提高。     

木塑复合材料界面相容剂的研究进展

木塑复合材料是一种新型的材料,由于其优越的综合性能而越来越受人们所关注.主要介绍了国内外木塑复合材料界面相容剂的分类及其在复合材料中的应用、表征等方面的研究进展.其中,界面相容剂在木塑复合材料中的表征手段主要介绍了静态力学性能测试、动态力学热分析测试(DMA)、接触角测定、扫描电镜(SEM)观测法、傅利叶红外光谱法(FTIR)测定以及X射线光电子能谱法(XPS)测定,并重点闸述了接枝改性聚合物型界面相容剂的制备、反应机理、表征等.闸述了国内木塑复合材料界面相容剂的发展状况,最后介绍了木塑复合材料界面相容剂的发展趋势.     

PP/空心玻璃微珠复合材料非等温结晶研究

采用熔融共混挤出的方法,制备了聚丙烯(PP)/空心玻璃微珠(HGB)复合材料,用差示扫描量热法研究了PP和PP/HGB复合材料的非等温结晶过程,并通过Jeziorny和莫志深方程研究了非等温结晶动力学。结果表明,随降温速率的增大,PP和PP/HGB复合材料的结晶峰温和结晶度降低,结晶速率增大;HGB的加入降低了PP的结晶速率。     

Enhanced interfacial adhesion via interfacial crystallization between sisal fiber and isotactic polypropylene: direct evidence from single‐fiber fragmentation testing

Bioresource natural sisal fiber (SF) was used to prepare single fiber‐reinforced isotactic polypropylene (iPP) composites. Three kinds of interfacial crystalline morphologies, spherulites, medium nuclei density transcrystallinity (MD‐TC) and high nuclei density transcrystallinity (HD‐TC), were obtained in the single fiber‐reinforced composites by implementing quiescent or dynamic shear‐enhanced crystallization and by modulating the compatibility interaction between SF and iPP. The development of interfacial shear strength (IFSS) during the interfacial crystallization process was demonstrated for the first time using a combination of single‐fiber fragmentation testing and optical microscope observation. A close correlation between IFSS and morphological characteristics of interfacial crystallization was well elucidated. The increases in IFSS were very different for spherulitic, MD‐TC and HD‐TC morphologies. The highest IFSS obtained was 28 MPa, after the formation of HD‐TC, which was about 62% of the tensile strength of neat iPP (45 MPa). These results offer powerful and direct evidence that interfacial crystallization could play an important role in the enhancement of interfacial adhesion of real SF/iPP composites. © 2013 Society of Chemical Industry     

Kinetic crystallization of polypropylene in ternary composites based on fiber‐reinforced PP‐EPDM blends

The crystallization of isotactic polypropylene (iPP) in its blends with ethylene–propylene–diene terpolymer (EPDM), reinforced with different fibers, is described in this work. In particular, the effects of both the fibers and the EPDM on the crystallization kinetics and morphology of iPP are analyzed. The study was performed using differential scanning calorimetry (DSC) in dynamic and isothermal conditions and optical microscopy. It was found that all the fibers act as effective nucleant agents on iPP crystallization independently of the blend composition. The results obtained highlight the accelerating effect of the fibers and of the EPDM on the PP crystallization up to a certain EPDM percentage. The halftime of crystallization, τ_1/2, and the overall crystallization rate, K_n, increase in the presence of all the fibers analyzed, showed the aramidic ones the most effective. The isothermal crystallization kinetics of ternary composites based on PP–EPDM blend matrices reinforced with different types of fibers can be modeled using the Avrami equation. On the other hand, the kinetic curves obtained under nonisothermal conditions provide a further confirmation of the nucleating action of the fibers on the PP crystallization. Optical polarizing microscopy was also used to investigate the effect of EPDM on the spherulite growth and the transcrystallinity phenomenon on the surface of the fibers. The results of such analysis showed that the transcrystallinity phenomenon is hindered at high rubber percentages. As in the case of the rate of crystallization, the highest proportion of transcrystallinity was observed in the presence of the aramidic fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1063–1074, 2001     

Interfacial Mechanical Characterization of Nicalon SiC Fiber/Alumina-Based Composites

Interfacial mechanical properties of both Nicalon SiC/aluminum borate and Nicalon SiC/aluminum phosphate with various fiber coatings and heat treatments were evaluated using a commercially-available indenter to induce fiber sliding during load cycling experiments. Varying degrees of sliding due to different coating materials were found. The interfacial characteristics including the shear, the residual axial fiber, and debond stresses were estimated by matching the experimental stress-displacement curves with curves predicted from an existing model. The elastic modulus and hardness of the interphase/interface in ceramic matrix composites were also evaluated. These results provided important insights into the ultimate mechanical performance of fiber-reinforced ceramic-matrix composites.     

Interfacial Mechanical Characterization of Nicalon SiC Fiber/Alumina-Based Composites

Interfacial mechanical properties of both Nicalon SiC/aluminum borate and Nicalon SiC/aluminum phosphate with various fiber coatings and heat treatments were evaluated using a commercially-available indenter to induce fiber sliding during load cycling experiments. Varying degrees of sliding due to different coating materials were found. The interfacial characteristics including the shear, the residual axial fiber, and debond stresses were estimated by matching the experimental stress-displacement curves with curves predicted from an existing model. The elastic modulus and hardness of the interphase/interface in ceramic matrix composites were also evaluated. These results provided important insights into the ultimate mechanical performance of fiber-reinforced ceramic-matrix composites.     

An analytical model for spherulitic growth in fiber-reinforced polymers

An analytical model for the isothermal crystallization of fiber reinforced polymers is presented. The model is based on approximate expressions for the volume of intersection between a sphere and cylinder. These expressions are used to account for the effect of the fibers on the overall crystallization process. Expressions for the average volume of spherulites truncated by the fibers are computed. The crystallization process is divided into time frames during which specific types of fiber truncations are encountered. Three different time sequences for the occurrence of the truncations are also derived according to the fiber volume fraction. The depressing effect of the fibers on the overall crystallization process is demonstrated with simple examples. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1677–1687, 1998     

聚丙烯／滑石粉复合材料的等温结晶动力学

用差示扫描量热法(DSC)研究聚丙烯(PP)及PP／滑石粉复合材料的等温结晶过程。用Avrami方程全面分析PP／滑石粉的等温结晶动力学，并由此获得相关的动力学参数；用Kissinger方程研究滑石粉对PP／滑石粉复合材料结晶活化能的影响。研究表明：加入滑石粉后明显提高PP／滑石粉复合材料的结晶速率和结晶度；证明滑石粉能促进PP材料的结晶，并在PP结晶过程中起到异相成核作用。PP／滑石粉复合材料的等温结晶过程属于典型的异相成核机理。     

Transcrystallinity in Surface Modified Aramid Fiber Reinforced Nylon 66 Composites

Aramid (kevlar‐49) fibers were surface treated by two different methods to induce roughness and then used to produce unidirectional nylon 66 based composites. The transcrystallinity generated around the treated fibers was characterized by SEM and polarized light microscopy and compared with the regular transcrystalline layers produced by pristine aramid under the same processing conditions. The treated fibers generated a double transcrystalline layer, the inner layer being thinner and more compact than the regular nylon 66 transcrystallinity. In addition, mechanical testing of the composites showed the longitudinal Young's modulus of the treated fiber composites to be significantly higher than the control in a wide range of fiber volume fractions.

Polarized light microscopy picture of double transcrystallinity in Br/NH₃ treated aramid fiber reinforced nylon 66.