Title: OUT-OF-AUTOCLAVE PROCESSING OF PHTHALONITRILE COMPOSITES WITH PREPREG RHEOLOGY OPTIMISATION
Abstract: Out-of-autoclave (OOA) processing features cost-effective industrial production of composites without the employment of autoclave ovens, including resin transfer moulding (RTM) and vacuum-bag-only (VBO) techniques. Because VBO processing cures composites at deficient pressure (1 atm maximum), greater care must be taken with prepreg handling and curing parameters design to achieve good part quality. In this work, we studied the influence of prepreg rheology of unidirectional carbon fiber/phthalonitrile prepreg on void formation in composite panels in VBO processing. Carbon fiber/phthalonitrile prepregs were manufactured by hot-melt process. A heat pre-treatment was introduced to control prepreg rheology during curing cycles. Rheological measurements using parallel-plate rheometer were taken on untreated and heat pretreated prepreg samples. It is found that a two-hour heat pre-treatment on prepregs before curing enhanced their viscosity to a suitable level that it avoided excessive resin loss and generated almost void-free VBO composites. Void content was reduced from 6.3% to 0.1%. Fully cured phthalonitrile composites exhibit good mechanical properties and show no sign of glass transition up to 450 oC.
Authors: Qin Lei, Baogang Sun, Hanqiao Shi, Peiluo Shi
Conference: CAMX 2017 –Orlando