Recently, CRG (Cornerstone Research Group Inc.) has introduced a completely new polymer system that has demonstrated high-temperature resistance like a polyimide (service temp. 300-450°C) as well as ultra-low flammability, heat release and smoke release, yet is similar to two-part epoxy resins in processability and cost. Moreover, these systems cure to a thermoplastic state at temperatures below 110 °C, cross-link to a thermoset at temperatures above 110 °C and can be converted to an almost pure carbon material at higher temperatures.
MG Resins can be combined with fiber reinforcement using conventional processing techniques, offering the potential for low-cost, high temperature structural composites. Water is the only volatile generated, thus processing does require management of porosity, similar to condensation-reaction polymers like phenolics and polyimides. However, initial testing of MG Resin composites shows an order of magnitude lower heat release vs. phenolics.
MG 1000 test samples were made using glass and carbon fiber fabrics and carbon fiber felt using vacuum infusion and hand layup. Carbon fiber panels and carbon felt panels were autoclave cured at 200-250°C and 100 psi with a 2-hr post-cure at either 250°C or 315°C. Glass fiber specimens were oven-cured at 250°C. MG 3000 test samples were prepared in a similar manner. Syntactic test panels were also produced using milled fiber and resin in an effort to explore low-density materials for potential use in ablative and thermal protection systems (TPS) for spacecraft. Overall, the resulting composites processed well, though further optimization of polymer formulations, processing and cure cycles is ongoing to reduce void content. Programs are also in progress to fully characterize the MG 1000 and MG 3000 resin systems and composite laminates.
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