聚醚砜酮树脂基碳纤维复合材料的性能研究

以含二氮杂萘联苯型聚醚砜桐（PPESK）树脂为基体，填加短碳纤维（CE）用溶液共混共沉淀，热压模塑方法研制出PPESK基碳纤维复合材料，研究了CF处理方法，CF含量，等离子体处理材料表面及摩擦条件（如线速度）对材料的摩擦磨性能的影响，利用KYKY100B扫描电镜观察材料磨损表面，分析了PPESK树脂及其复合材料的磨损机理，摩擦磨损实验结果表明PPESK／CF与纯树脂相比，摩擦系数减小1倍，磨损率下降2个数量级，纯树脂的磨损机理主要是创削磨损和粘着磨损，而复合材料的磨损特性主要表现为粘着磨损，且具有优异的耐热性能，是一类新型无油自润滑的耐高温低摩擦材料。     

CF/PPEK、CF/PPES复合材料高温力学性能研究

采用预浸热压成型工艺制备碳纤维增强杂萘联苯聚醚酮(CF/PPEK)和碳纤维增强杂萘联苯聚醚砜(CF/PPES)单向复合材料试样,通过对试样在常温和高温条件下的力学性能测试与分析,研究了高性能热塑性复合材料在高温条件下力学性能及其强度和模量保留率的变化规律.实验表明,在250℃下其拉伸和弯曲强度及模量的保留率均在60%以上,仍具有极高的承载能力.利用Tr-n预测模型对这两种复合材料高温力学性能进行的预测结果与试验值基本吻合,从而验证了这个模型的可行性.     

Influence of cooling rate on interlaminar fracture properties of unidirectional commingled CF/PEEK composites

The influence of cooling rates on the mechanical property profile (transverse flexure properties and modes-I and -II interlaminar fracture toughness) has been investigated for unidirectional commingled CF/PEEK composites. A laboratory hot press with a steel mould was used to process the composites at 400°C for 60 min, at an applied pressure of 1 MPa. Cooling rates from fast (quenching in oil) to slow (hot press cooling) were achieved at ambient pressure. The results indicate that different matrix morphology was found at different cooling conditions, although deconsolidation occurred in the CF/PEEK composites during cooling. When the cooling rate was shifted from slow to fast, consolidation quality of the CF/PEEK composites was improved. The resulting effect of the consolidation quality and cooling rates on the mechanical property profile of commingled CF/PEEK composites is presented. It was found that the effect of the cooling rate on the mechanical property profile of the commingled CF/PEEK composites could not be isolated from the consolidation quality.     

Ekonol/G/MoS2/PEEK复合材料的力学性能

用模压方法制备了Ekonol／G／MoS2／PEEK复合材料，并对其力学性能(含拉伸强度、弯曲强度、冲击强度和压缩强度)进行了研究。结果表明：Ekonol的加入，使Ekonol／G／MoS2／PEEK复合材料的压缩强度提高，拉伸强度、弯曲强度和冲击强度有所降低．但并不妨碍其作为结构零件使用；当Ekonol含量为25％左右时，复合材料具有较为理想的综合力学性能。     

A comparative study on mechanical properties of carbon fiber/PEEK composites

The aim of this work was to improve mechanical properties such as flexural strength and interlaminar shear strength (ILSS) of polyetheretherketone (PEEK) thermoplastic polymer which has very high processing temperature due to its high melting temperature. Carbon fiber (CF) surface was modified by two different methods: oxidative and non-oxidative. Piranha solution and chromate solution were used for chemical treatment (oxidative treatment), and silicone based polymers were used for polymer coating (non-oxidative). The changes on the surface structure and surface chemistry were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR), respectively. FTIR results indicate that coating fibers decreases carbon element content, whereas increases the oxygen and silicone content as well as their functional groups on the surface. Flexural strength and ILSS properties of CF/PEEK composites were measured according to ASTM D-790 and ASTM D2344, respectively.     

碳纤维织物/PEEK热塑性树脂基复合材料光学反射镜研究

研究了碳织物增强热塑性PEEK树脂基复合材料的力学性能、部分空间性能及光学反射性能.研究结果表明,碳织物/PEEK复合材料具有优异的力学性能、空间性能、耐辐照性能和光学反射性能;在1×10-3Pa真空中可凝挥发物(CVCM)为0、水气回收量(WVR)为0.08%,并制成φ128mm反射镜,测试了反射镜的反射率为96.89%.碳织物增强热塑性PEEK树脂基复合材料是一种适合空间环境的高性能复合材料,可以用于制作光学反射镜.     

The effects of strain-rate and temperature on the interlaminar fracture toughness of interleaved PEEK/CF composites

The effect of interleaving on the interlaminar fracture behaviour of unidirectional and woven-fabric fibre composites based upon continuous carbon fibres (CF) and poly(ether ether ketone) (PEEK) has been investigated over a wide range of temperature and crack speed. The fracture data obtained from mode I and mode II tests have been analysed using the time-temperature equivalence postulate and the results are discussed in terms of fracture micromechanisms. The insertion of a resin-rich layer between laminae was found to increase significantly the fracture resistance of the composites, whitout altering its dependence on crack speed.     

紧张热定型工艺对多壁碳纳米管/聚醚醚酮复合纤维结构和性能的影响

采用熔融共混纺丝工艺制备多壁碳纳米管(MWCNTs)质量分数分别为0.1%和0.5%的MWCNTs/PEEK(聚醚醚酮)复合纤维,研究了紧张热定型过程中热定型温度和降温速率对复合纤维结构和性能的影响。采用TEM、SEM、DSC、DMA、XRD和单纤维电子强力仪研究了复合纤维的形貌、结构和性能。结果表明:复合纤维的热定型温度和冷却降温速率对其杨氏模量、拉伸强度和断裂伸长率均有影响,经过热定型处理,复合纤维内部MWCNTs的取向程度明显提高。280℃热定型、1.5℃/min冷却纤维的拉伸强度达384MPa,杨氏模量为0.62GPa,断裂伸长率28%,拉伸强度和杨氏模量分别较130℃热定型纤维提高了147%和19%,获得了优化复合纤维性能的最佳工艺条件。      

Thermal aging effects on mechanical and tribological performance of PEEK and short fiber reinforced PEEK composites

The effects of thermal aging on the properties of unfilled and random oriented short fiber reinforced PEEK and its composites have been studied. After the isothermal aging process, there is a remarkable decrease in degree of crystallinity but more organized crystallize structure achieved. As a result of transcrystalline layer formation, there was a considerable increase in the flexural modulus of materials. Thermal aging affects the impact properties of filled and unfilled PEEK dramatically. F_max, E_max and E · F_max results of both filled and unfilled aged PEEK and its composites are dramatically decreased. Thermal aging makes materials more brittle and there was a significant decrease in toughness. % Crystallinity is not the unique parameters to determine polymer’s performance. The orientation of crystals is another important parameter in microstructure and plays important role in mechanical and tribological properties of PEEK and its composites. There is a close relationship between thermal aging and microstructure. But there is not a linear relationship between microstructure and tribological properties. Microstructural changes after thermal aging serves developed mechanical properties. Increased mechanical properties results in improved tribological properties.     

Effects of tension heat-set process on structures and properties of MWCN~/PEEK composite fibers

采用熔融共混纺丝工艺制备多壁碳纳米管（MWCNTs）质量分数分别为0．1％和0．5％的MWCNTs／PEEK（聚醚醚酮）复合纤维,研究了紧张热定型过程中热定型温度和降温速率对复合纤维结构和性能的影响。采用TEM、SEM、DSC、DMA、XRD和单纤维电子强力仪研究了复合纤维的形貌、结构和性能。结果表明：复合纤维的热定型温度和冷却降温速率对其杨氏模量、拉伸强度和断裂伸长率均有影响,经过热定型处理,复合纤维内部MWCNTs的取向程度明显提高。280℃热定型、1．5℃／min冷却纤维的拉伸强度达384MPa,杨氏模量为0．62GPa,断裂伸长率28％,拉伸强度和杨氏模量分别较130℃热定型纤维提高了147％和19％,获得了优化复合纤维性能的最佳工艺条件。     

Consolidation of unidirectional CF/PEEK composites from commingled yarn prepreg

Relationships between impregnation mechanisms, consolidation quality and resulting mechanical properties of CF/PEEK thermoplastic composites manufactured from a commingled yarn system have been investigated. A small compression mould was used to apply the different processing conditions (i.e. pressure, holding time and processing temperature). The consolidation quality of finished samples was characterized mainly through microscopic studies of the microstructure of the material associated with density measurements and evaluations of mechanical properties using a small transverse flexure testing facility. A model for qualitatively describing the impregnation and consolidation processes in commingled-yarn-based thermoplastic composites was developed, which predicts variations of void content during consolidation as well as the time, temperature and pressure required to reach full consolidation. Good correlations between predictions and the experimental data indicate the success of the approach. For a desired, minimum level of void content (X_v = 0.5%), optimum processing windows for manufacturing of CF/PEEK composite parts from the commingled yarn preform are suggested.     

CF/PA12 composite femoral stems: Manufacturing and properties

The fabrication process for a novel carbon fiber-reinforced polymer (polyamide 12) composite femoral stem using inflatable bladder molding was studied. Effect of processing temperature, holding time and applied internal pressure on the consolidation quality of the composite was investigated. Consolidation quality was evaluated by density and void content measurements and scanning electron microscope analysis. As expected, void content (porosities) and presence of large resin pockets were found to increase for lower processing temperature, holding time and applied pressure. Crystallinity as well as melting temperatures measured using differential scanning calorimetry could be related to molding conditions. A progressive reduction of the previous thermal history (crystalline peak of neat composite) and an increase in crystallinity were obtained for higher molding temperature. Static compression testing with void content analysis of molded specimens was used to determine optimal molding conditions. The composite structure molded showed compressive modulus close to cortical bone’s. Compression load at failure of composites molded in optimal conditions were found to be three times higher than those of femoral bone for jumping on one leg or 10 times those for normal gait. The molded composite structure appears to be an excellent candidate for femoral stems used in total hip arthroplasty.     

Nonisothermal crystallization behavior and mechanical properties of PEEK/SCF/nano-SiO2 composites

Nonisothermal crystallization of hybrid PEEK composites reinforced with short carbon fibers (SCF) and nano-SiO₂ (1, 1.5 and 2 wt%) was investigated using DSC. Composites were fabricated by melt-mixing process at 400 °C. The Size of the nanoparticles was 13 nm. Samples were cooled from 410 °C to 25 °C with cooling rates of 10, 30, 50 and 70 °C min⁻¹. The onset, peak and end crystallization temperatures were investigated as well as absolute crystallization percentage and crystallization time. Avrami, Ozawa and Ozawa–Avrami equations were fitted to the data in order to investigate the crystallization kinetics. Mechanical behaviors of the composites were examined using nanoindentation and nanoscratching. DSC results revealed that absolute crystallization percentage increases in PEEK/SCF/1%SiO₂ and PEEK/SCF/1.5%SiO₂ samples compared to PEEK/SCF, however it decreases by adding more nano-SiO₂. Ozawa–Avrami is proved to be the best model for describing crystallization behavior of the composites while Avrami equation was suitable for describing a part of the crystallization process. The Avrami and Ozawa–Avrami constants were calculated. Besides, adding SCFs and nano-SiO₂ into PEEK results in a significant decrease in plasticity index, while increases the resistance to plastic deformation of the composite.     

Low temperature irradiation effects on mechanical properties of epoxy used in superconducting magnets

Superconducting magnets for fusion devices are greatly influenced by the radiation environment and the principal radiation-induced troubles arise from changes in the mechanical fracture behaviour of organic materials used as insulating and/or potting materials. Small compression test specimens of epoxy resin were tested after gamma and pile irradiation at low temperatures. Three kinds of mechanical properties, ie a — breaking stress, b — breaking strain and c — elastic moduli were investigated. A statistical analysis of the data from a large number of small specimens revealedt the following: 1. the different effects of gamma and neutron irradiation on the fracture behaviour were observed. This fact suggests that a simulation study by gamma irradiation is not valid for neutron irradiation. 2. in the case of reactor irradiation overall softening was induced accompanied by local hardening and embrittlement. A qualtitative explanation of the above results is presented and their relationship to the performance of the magnets is given.     

Recycling effects on microstructure and mechanical behaviour of PEEK short carbon-fibre composites

The effect of recycling on microstructure and mechanical properties has been evaluated for injection-moulded poly-ether-ether-ketone (PEEK) composites reinforced with 10% and 30% short carbon fibres. Microstructure characterization was carried out by determining fibre length distributions, PEEK molecular weight, and by SEM observations of fracture surfaces before and after processing. These studies reveal degradation of fibres and matrix during recycling. Tensile Youngs modulus and strength, as well as impact strength reductions are presented for recycled composites.     

The effects of deforming knitted glass fabrics on the basic composite mechanical properties

The effects of deforming knitted fabrics on the tensile and compressive properties of their composites have been investigated for the weft-knit Milano rib fibre architecture. The properties have been studied for both the course and wale directions for composites with fabrics deformed in either of the two directions. It was found that any change in the mechanical properties of the deformed composites with respect to their undeformed counterpart is strongly related to the changes in the knit structure brought about by the induced deformation to the knitted fabric. Deformation in the knitted fabric also affects the tensile fracture mode whereby increased deformation, be it wale- or course-wise, transforms transverse fracture to shear fracture in either loading axis. On the contrary, the compressive fracture mode is insensitive to fabric deformation. Fractographic studies using stereo-optical and scanning electron microscopy have further revealed that tensile failure is caused by fibre breakages occurring at two locations of the knitted loops—one, at the leg components and, two, at fibre crossover points, whilst compression failure is controlled by Euler buckling of the looped fibres of the knitted composite. All these characteristics were revealed to be related to the microstructure of the knitted composite laminates.     

基于导热板的碳纤维增强聚醚醚酮复合材料感应焊接温度调控

研究了碳纤维增强聚醚醚酮(CF/PEEK)复合材料感应焊接中厚度方向及焊接面内的温度分布及调控.基于对温度分布结果的分析,使用导热板结合真空袋压的方式对CF/PEEK进行感应焊接,结合使用合适的功率及加热时间,测试了焊接件的单搭接强度,观测分析了焊接件的断裂形貌.结果 表明,导热板对层合板表层和边缘均有良好的散热效果;...