HIGH TEMPERATURE POLYMER MATRIX-CARBON FIBER COMPOSITES-PERFORMANCE ISSUES AND FUTURE NEEDS

摘要

The durability thresholds and new materials needs for high temperature polymer matrix carbon fiber composites, PMFC's, for present and future military and commercial aircraft and reusable space vehicles will be discussed. The failure sequence paths for (i) surface microcrack initiation that ultimately leads to internal structural damage and (ii) internal hygrothermal induced blister damage for bismaleimide, BMI and polyimide, PI, - carbon fiber composites in present and future aerospace stress-time-temperature-moisture-chemical service environments in terms of the critical physical, chemical and mechanical parameters that control composite damage initiation and propagation on the molecular, microscopic and macroscopic structural levels will be presented. For BMI-C fiber composites, our latest characterization of the cure reactions and predictions that little further cure and embrittlement occurs over long-time service environments in the 175-200 deg C temperature range will be presented. For PI-C fiber composites evidence for matrix chemical hygrothermal degradation, lack of matrix toughness translation to composite properties and matrix toughness deterioration caused by physical aging will be presented and discussed in terms of design decisions and lifetime predictions. In the light of these studies new accelerated synergistic testing methodologies and materials developments needs for protective coatings, enhanced performance fiber-matrix interfaces and economic carbon filled composites will be summarized.