Development of a Cure/Postcure Cycle for PETI-330 Laminates Fabricated by Resin Transfer Molding

Abstract

As part of our product development effort for PETI-330, an investigation to determine the effect of a thermal cure cycle and thermal postcure treatment on laminate properties was conducted. Laminates of PETI-330/T650-35 carbon fabric (un-sized) were fabricated by resin transfer molding (RTM) using a high temperature injector. The resin was degassed at 525-550 °F (274-288 °C) and subsequently injected into an Invar tool and cured for 1 h at 700 °F(371 °C). The laminates were characterized for quality by ultrasonic inspection and acid digestion, the dry glass transition temperatures (Tg values) were determined by dynamic mechanical thermal analysis (DMTA). Specimens (7.6 cm × 7.6 cm) were subsequently machined from the panels and free-standing postcures were performed at 600 °F(316 °C), 625 °F (329 °C), 675 °F (357 °C) and 700 °F(371 °C) for 6 and 12 h at each temperature in flowing air at 1 atmosphere. The postcured specimens were characterized for weight loss, and dry and wet Tg values. The postcured laminates were machined into specimens approximately 7.6 cm × 6.4 cm and isothermal aging was performed for 100 h at 625 °F (329 °C), 650 °F(343 °C) and 700 °F(371 °C). After isothermal aging, the aged specimens were characterized for weight loss, dry and wet Tg and micro-cracking using optical microscopy. The results of this study are presented. Based on these results, the postcure conditions that gave the best combination of results were identified.