碳纤维／聚酰亚胺耐高温复合材料成型工艺及其性能的研究

本文研究了碳纤维／聚酰亚胺复合材料的成型工艺及其力学性能和高温力学性能以及热学性能，指出了评价耐高温复合材料的长期耐热性和短期耐热性的方法，为用户制作了碳纤维／聚酰亚胺耐高温复合材料产品，并通过了高温试验。     

M40J/EC复合材料的温湿效应

用湿法缠绕技术制作了高模量，高强度石墨纤维增强高韧性低吸湿环氧树脂（M40J／EC）预浸料，对热压罐固化的M40J／EC复合材料的室温，高温干态和湿态力学性能进行了研究。与高模量石墨纤维／酚醛环氧树脂（40／4211）得合材料相比，M40J／EC复合材料的各项力学性能均有很大程度的提高，且有优异的耐湿热性能，在130℃干，湿态下，其弯曲强度，弯曲弹性模量和层间剪切强度的保持率较高。     

工艺因素对RTM成型聚酰亚胺复合材料性能的影响

采用低熔体粘度适用于液态成型的聚酰亚胺树脂研究了树脂传递模塑（RTM）工艺中树脂注射压力、注射流速、固化温度对碳纤维增强聚酰亚胺复合材料性能的影响，以确定最佳的成型工艺参数。结果表明，随着注射压力增大，复合材料的玻璃化转变温度下降，层间剪切强度提高，弯曲强度略有提升。随着注射流速增加，复合材料玻璃化转变温度不变，层间剪切强度和弯曲强度降低。随着固化温度升高，复合材料的玻璃化转变温度升高，但固化温度达到400℃时，层间剪切强度和弯曲强度明显降低。根据树脂工艺性，综合考虑复合材料内部质量、耐热性和力学性能，采用注射压力1.2 MPa，注射流速15 mL/min以及固化温度380℃的成型工艺较优。     

多官能环氧/DDS体系性能研究

以氯代四官能环氧树脂（EP）为基体树脂，二氨基二苯砜（DDS）为固化剂，碳纤维为增强材料，制备了多官能EP／DDS体系及其复合材料。通过对体系的凝胶时间，粘度－温度曲线，DSC曲线的分析，确定了体系的固化工艺为120℃/1h＋150℃/2h＋175℃/3h；其浇注体和复合材料层压板的力学性能较好，与美国Narmco公司的同类材料相当。     

高性能复合材料弯曲疲劳性能研究

用湿法缠绕技术制作了CF／5228预浸料,对热压罐固化的CF／5228复合材料的力学性能和弯曲疲劳性能进行了研究,并用扫描电镜、电子显微镜等对复合材料的疲劳损伤机理进行了微观表征和理论探讨。研究表明,M40J／5228复合材料比M40／5228具有更为优异的耐疲劳性能。复合材料的疲劳损伤主要有纤维断裂、基体开裂和界面剪切破坏3种表现形式,通常复合材料构件的疲劳破坏多为3种形式的综合表现。基体增韧、选用高强高模碳纤维、界面强化和铺层优化是提高复合材料构件耐疲劳性能有效手段。     

高压气体压缩机阀片用材料的研究

根据气体压缩机阀片的要求，制备了碳纤维(CF)和二硫化钼(MoS2)填充热塑性聚酰亚胺(PI)复合材料；研究了不同组成材料的力学性能、摩擦性能，考察了载荷对材料摩擦性能的影响，观察了材料磨损面形貌，并对磨损面进行了元素分析。结果表明：通过填充碳纤维，可以有效增强聚酰亚胺材料的强度；填充MoS2后，材料的力学性能有所下降，但可有效提高材料的极限PV值；随载荷增加，材料的磨损率及摩擦系数都不断减小；该材料适于作高压气体压缩机构件。     

快速固化环氧树脂/碳纤维复合材料的性能

利用差示扫描量热分析仪研究了一种快速固化环氧树脂体系的固化工艺参数,确定了以真空辅助树脂灌注工艺制备快速固化环氧树脂/碳纤维复合材料的成型方法,并与常规固化环氧树脂体系制备的碳纤维复合材料进行对比,采用傅里叶变换红外光谱仪对两种材料的树脂基体进行了分析,考察了两种复合材料的纤维含量、孔隙率及力学性能,最后通过扫描电子显微镜观察了快速固化树脂基体与碳纤维的界面结合性。结果表明,快速固化树脂在99℃下固化6 min后固化度可达96%,能够大幅缩减碳纤维复合材料的成型时间,以其制备的碳纤维复合材料拉伸强度比常规固化环氧树脂复合材料高11.20%,弯曲强度高16.92%,纵横剪切强度高7.44%,快速固化树脂与碳纤维界面结合性良好。     

碳纤维／环氧复合材料天线肋条的研制

介绍某通讯天线系统中碳纤维／环氧复合材料肋条的设计要求和制备路线, 研究了材料的铺层设计和固化工艺等, 达到了天线肋条达到了设计要求。     

单向碳纤维复合材料微观形貌与性能相关性研究

利用金相显微镜、电子探针、扫描电镜对不同基体的单向碳纤维复合材料截面、界面进行了观察比较。结果表明：相同工艺条件下制备的几种不同基体碳纤维复合材料中，环氧树脂基碳纤维复合材料缺陷多，但纤维与基体的界面结合强，材料抗拉强度高；酚醛树脂基碳纤维复合材料与乙烯基酯碳纤维复合材料缺陷少，但界面结合差，材料抗拉强度低；材料界面结合状态与工艺参数有关。改性酚醛树脂、探索合理的生产工艺参数对改善界面结合状态，提高材料综合机械性能具有重要意义。     

国产碳纤维增强树脂基复合材料的界面结合性能研究

研究了国产高强中模碳纤维T800、高模碳纤维M50J及M55J的力学性能及其增强树脂基复合材料的界面结合强度(ILSS),并与日本东丽公司同级别碳纤维进行对比。结果表明:国产M55J碳纤维的拉伸模量为568 GPa,拉伸强度为4.50 GPa,日本东丽公司M55J的拉伸模量为561 GPa,拉伸强度为4.10 GPa,国产高模碳纤维表面石墨化程度高于日本东丽碳纤维,表面呈现更高惰性,其增强树脂基复合材料的ILSS略低于日本东丽碳纤维复合材料;将高强中模碳纤维与高模碳纤维混合后对树脂基体进行增强,混合碳纤维中随着高强中模碳纤维含量提高,其复合材料的ILSS提高幅度也随之增加。     

含苯炔基侧链的聚酰亚胺树脂及其复合材料

采用联苯酐(3,4′-BPDA)与4,4′-二氨基二苯醚(4,4-ODA),3,5-二氨基-4′-苯炔基二苯甲酮(DPEB),苯炔基苯酐(PEPA)制备了不同分子质量的聚酰亚胺树脂。通过流变分析,热重分析,红外光谱,动态热力学分析及静态力学性能测试等研究了分子结构,分子质量等因素对聚酰亚胺树脂耐热性和力学性能的影响。结果表明,合成的聚酰亚胺树脂具有优异耐热性能和较高的韧性,固化后树脂的玻璃化转变温度为379℃,5%热失重温度高于550℃,并且浇注体的拉伸强度是61 MPa,断裂伸长率是6.2%.碳纤维复合材料的室温弯曲强度为1 850 MPa,层间剪切强度为84 MPa,316℃时弯曲强度为946 MPa,剪切强度为46 MPa,具有良好的高温力学保持率。     

Effect of degree of cure and fiber content on the mechanical and dynamic mechanical properties of carbon fiber reinforced PMR-15 polyimide composites

A unidirectional continuous carbon fiber reinforced polyimide composite is fabricated using the PMR-15 polyimide as a matrix. Mechanical and dynamic mechanical properties of the composite are studied. The effect of variation of the fiber content ranging from 55% to 70% by volume on the properties of the composite is determined. The effects of the laminate thickness and degree of curing of the matrix on the Izod impact strength are examined. The effect of the degree of curing of the matrix on the dynamic mechanical spectrum is studied. Finally, variables such as humidity, environment temperature, vacuum, and pressure during laminate processing, and variation of monomer composition are discussed in terms of change in matrix structure, which is reflected in a variation of Tg between batches.     

Mechanical properties and mechanism of the degradation process of 316°C isothermally aged graphite fiber/PMR-15 composites

A series of graphite fiber/PMR-15 polyimide composites, isothermally aged at 316°C in flowing air (100 cc/min) for time periods up to 2000 h, were investigated for mechanical property changes, fiber/resin interface changes, overall dimensional changes, and weight loss. The mechanism of the degradation process is suggested based on shear and flexural property measurements at room temperature and 316°C, optical micrographs of composite cross sections, and SEM analysis of fractured surfaces. The fiber materials investigated in composite form were Celion 6000 unsized and epoxy sized. G40-700 unsized and epoxy sized, and T40R and IM6 both unsized.     

Study of the processing chemistry of polyimides with thermogravimetry/Fourier transform infrared/mass spectrometry techniques

One of the fundamental aspects of the carbon fiber‐reinforced, high‐temperature polyimide composite AFR700B/T650‐35, namely, the curing chemistry involved in the polyimide formation, was studied in real time with thermogravimetry/Fourier transform infrared (FTIR)/mass spectrometry (MS) evolved‐gas analysis techniques. The off‐gas reaction products identified by FTIR and MS essentially confirmed the literature polyimide curing mechanisms. However, the FTIR/MS data obtained could also accommodate a reversed curing chemistry in which the elimination of water from amide ester formation occurred first and was followed by the release of methanol from subsequent imidization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2213–2224, 2002     

High temperature polyimides,chemistry and properties

Selected polyimide resins are capable of long term use at 316°C for over thousands of hours in an inert atmosphere, and approximately 2000 hours in air. This attractive feature of polyimides has provided an avenue for applications at elevated temperature (316°C) as adhesives, coatings, and secondary structures in the form of fiber reinforced polyimide composites. The chemistry and properties of thermoplastic and crosslinked polyimides, including addition-type polyimides, will be discussed. The chemical considerations of both commercial and experimental polymer materials, Avimid N, PMR-15, LARC TPI, IP-600, L-20, and L-30 as they affect processing are reviewed. General physical, thermal, mechanical, and thermo-oxidative stability properties of polyimides are presented Room temperature and 316°C mechanical properties of unaged and 1000 hr 316°C aged high temperature polymer composites will also be discussed.     

一步法聚酰亚胺纤维的制备及其性能研究

利用实验室自制的聚酰亚胺(P)I溶液,通过干湿法纺丝制得PI初生纤维。在以水和N-甲基吡咯烷酮(NMP)混合溶液(体积比8∶2)作为凝固浴,凝固浴温度为5～15℃的条件下,所得初生纤维结构均匀密实,纤维截面呈圆形或腰圆形。在对初生纤维进行热处理时,随着热处理温度升高和时间增加,PI纤维的力学性能增强。当热处理温度为300～320℃、时间为30 min时,PI纤维的力学性能最优,其断裂强度和初始模量达到2.474 cN/dtex和50.066 cN/dtex;当热处理温度高于320℃,时间超过1 h,纤维力学性能又缓慢下降。纤维的热稳定性较好,在500℃左右仍具有较好的热稳定性。     

Tribological behavior of short‐fiber‐reinforced polyimide composites under dry‐sliding and water‐lubricated conditions

Polyimide composites reinforced with short‐cut fibers such as carbon, glass, and quartz fibers were fabricated by the polymerization of monomer reactants process. The mechanical properties of the composites with different fiber contents were evaluated. The friction and wear properties of the polyimide and its composites were investigated under dry‐sliding and water‐lubricated conditions. The results indicated that the short‐carbon‐fiber‐reinforced polyimide composites had better tensile and flexural strengths and improved tribological properties in comparison with glass‐fiber‐ and quartz‐fiber‐reinforced polyimide composites. The incorporation of short carbon fibers into the polyimide contributed to decreases in the friction coefficient and wear rate under both dry and water‐lubricated conditions and especially under water lubrication because of the boundary lubrication effect of water. The polyimide and its composites were characterized by plastic deformation, microcracking, and spalling under both dry and water‐lubricated conditions, which were significantly abated under the water‐lubricated condition. The glass and quartz fibers were easily abraded and broken; the broken fibers transferred to the mating metal surface and increased the surface roughness of mating stainless steel, which led to the wear rate increasing for the glass‐fiber‐ and quartz‐fiber‐reinforced polyimide composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The effect of curing history on the residual stress behavior of polyimide thin films

The effect of curing history on the residual stress behaviors in semiflexible structure poly(4,4′‐oxydiphenylene pyromellitimide) (PMDA–ODA) and rigid structure poly(p‐phenylene biphenyltetracarboximide) (BPDA–PDA) polyimide was investigated. Depending upon the curing history and different structures of polyimide, the residual stress behaviors and the morphology of polyimide thin films were detected in situ by using a wafer bending technique and wide angle X‐ray diffraction (WAXD), respectively. For the rigid structure BPDA–PDA polyimide, the residual stress and the slope decreased from 11.7 MPa and 0.058 MPa/°C to 4.2 MPa and 0.007 MPa/°C as the curing temperature increased, and the annealing process is done. However, for the semiflexible structure PMDA–ODA, the change of the residual stress and the slope was relatively not significant. In addition, it was found that the cured polyimide prepared at a higher temperature with a multistep curing process showed a higher order of chain in‐plain orientation and packing order than does the polyimide film prepared at a lower temperature with a one‐step curing process. These residual stress behaviors of polyimide thin films show good agreement with WAXD results, such as polyimide chain order, orientation, and intermolecular packing order, due to curing history. Specifically, it shows that the effect of curing history on residual stress as well as morphological change was significant in rigid BPDA–PDA polyimide but, not in semiflexible PMDA–ODA polyimide. Therefore, it suggests that the morphological structure depends upon curing history, and the polyimide backbone structure might be one of important factors to lead the low residual stress in polyimide thin films. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3287–3298, 1999     

Interaction between the reinforcement and matrix in carbon-fiber-reinforced composite: Effect of forming the thin layer of polyimide resin on carbon fiber by in situ polymerization

For the purpose of enhancing the reinforcement–matrix interaction in carbon-fiber-reinforced polymer composite, mechanical and spectroscopic studies were made on the epoxy resin composite reinforced with the carbon fiber coated with thin Layer of polyimide resin. On the loss modulus and loss tangent vs. temperature curves, a subtransition appears at a temperature above the primary transition. The T-peel strength of a laminated specimen and the fiber efficiency factors for modulus and strength are larger than those of the composite reinforced with nonpolyimide treated fiber. These results show the increased interaction between the epoxy resin and the carbon fiber coated with polyimide resin. The occurrence of specific interaction between an epoxy resin and the polyimide resin are recognized on fourier transform infrared spectra.     

Development of soybean oil‐based composites by solid freeform fabrication method: Epoxidized soybean oil with bis or polyalkyleneamine curing agents system

Soybean oil‐based composites are prepared by the solid freeforming fabrication (SFF) method. Epoxidized soybean oil is solidified with a gelling agent, and composites are formed by fiber reinforcement. Glass, carbon, and mineral fibers are used in the formulations. The type of fiber and degree of fiber alignments affect the properties of the composites. In addition, the effects of curing agents, curing temperature, fiber combination, and fiber loading on mechanical properties of composites and dynamic analysis are studied and reported. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2100–2107, 2002