炭素繊維強化高耐熱性ポリアミド樹脂の繊維樹脂界面特性に及ぼす温度の影響

抄録

To enhance the application of Carbon Fiber Reinforced Thermoplastics (CFRTP) for automobile, it is important to understand the mechanical properties of CFRTP under service environmental conditions. Since the vehicle roof surface is exposed to high temperature, to clarify mechanical properties of CFRTP under high temperature environment is important for reliability assessment. Since the mechanical properties of CFRTP under high temperature environment depend on matrix resin, the highly heat resistant resin is preferred for the matrix of CFRTP. Among highly heat resistant resin, polynonamethyleneterephthalamide (PA9T) is expected to be used for the matrix of CFRTP due to its properties such as high heat-moisture resistance. Although the mechanical properties of neat PA9T resin at high temperature were evaluated and showing better heat resistance property than PA46 and PA6T, the potential of PA9T as the matrix of CFRTP have not been clarified yet. Since the mechanical properties of CFRTP are affected by not only the properties of reinforcing fibers and the matrix resin but also the properties of fiber/matrix interface, it is important to evaluate the effects of temperature on the fiber/matrix interfacial properties of CF/PA9T. In this study, single fiber pull-out tests at R.T., 40 °C and 80 °C, measurement of specific volume and softening point of the resin were conducted to evaluate the fiber/matrix interfacial properties of CF/PA9T model composites and the results were compared with these of CF/PA6 and CF/PA12 model composites. The resin expanded and interfacial shear strength of the CF/PA9T model composites decreased as temperature rose, and the decrease rate of interfacial shear strength of the CF/PA9T model composites was smaller than these of CF/PA6 and CF/PA12 model composites. Instead of chemical deterioration and softening of the resin, the reduction of residual stress at high temperature under 80 °C decreases the fiber matrix interfacial shear strength.