Abstract
Mono-end-capped PMR-type polyimide matrix resins were prepared by incorporation of carbonyl groups into the polymer backbone of second-generation PMR polyimide by two synthetic pathways. The matrix resin features, thermal processing characteristics of B stage resins as well as thermal and thermooxidative stability of the thermally cured polyimide materials, were systemically investigated. Experimental results indicated that the matrix resins were lowviscosity and stable homogeneous solutions with 50% solid content in ethanol, possessing good characteristics for preparation of carbon or graphite fiber prepregs or B-stage molding compounds. The thermally cured polyimide materials exhibited glass transition temperatures (Tg) of >470 0C and onset temperatures of the storage modulus of >440 'C, 100 'C higher than those of commercial materials. Continuous carbon fiber-reinforced composites were fabricated, which have very high Tg and onset temperature of storage modulus at 446 'C. Preliminary results demonstrated that the composites laminate exhibited high mechanical strength and mechanical property retention at 371 'C, superior to the properties of commercial composite materials (CF/PMR-1I-50).
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