Elevated-Temperature Thermal and Mechanical Behavior of Carbon Fiber/Graphite/PTFE/PEEK Composite

Abstract

Elevated-temperature thermal and mechanical properties of carbon fiber (CF)/graphite flakes (Gr)/PTFE filled PEEK composite are investigated by a combined experimental and theoretical study. In the experimental phase, the CF/Gr/PTFE/PEEK composite was fabricated by compression-molding, followed by a sintering process. Optical and electronic microscopy was performed to examine microstructure of the composite and X-ray diffraction (XRD) was conducted to provide morphological information. Dynamic-mechanical analysis (DMA) was performed to evaluate composite thermomechanical properties. Differential scanning calorimetry (DSC) and thermal-mechanical analyzer (TMA) were employed to determine heat capacity, glass transition temperature (Tg), coefficient of thermal expansion (CTE) and thermomechanical preperties of the composite at elevated temperature. To augment the experimental study, micromechanics modeling and analysis of the composite thermal and mechanical behavior are also conducted to better understand the fundamental nature of composite microstructure and environmental interaction. Good agreement was observed between the experimental data and theoretical predictions. The detailed effects of elevated temperature on CF/Gr/PTFE/PEEK composite thermoelastic (storage) and viscoelastic (loss) moduli, thermal expansion and heat capacity are determined.