Abstract
A processing-property relationship was studied by varying the final cure temperature for thin films of LaRC™ RP46 polyimide, a new PMR-15-like material. This new material incorporates a low toxicity diamine 3,4'-oxydianiline instead of the mutagenic 4,4'-methylenedianiline. Thin films of RP46 were cured at a final temperature of 316°C, 325 ° C, 350 ° C, and 371 ° C. Physical properties-including fracture toughness, size of plane-stress deforma tion zone, and tensile strength-were determined as a function of the final cure temperature. At lower cure temperatures (316°C and 325 ° C), the plastic defor mation zones exhibited diffuse shear yielding, similar to a semi-interpene trating polymer network. At higher cure temperatures (350 ° C and 371°C), the degree of crosslinking increased and as a consequence the size of the deforma tion zone was significantly diminished. The higher cure temperatures also decreased fracture toughness and tensile strength.
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