Preparation and composite properties of ethynylpolyimide hybrid resins

In this paper, one kind of novel ethynylpolyimide hybrid resin was prepared, and the propeties of laminate composites reinforced by silica cloth were evaluated. The synthesis was started with 4-phenylethynylphthalic anhydride (4-PEPA), 3-aminophenylacetylene (3-APA) and 1,1,3,3-tetramethyldisiloxane (TMDS). Upon thermal treatment, silicon-containing ethynylpolyimide was prepared in a solid state with low melting point. Novol hybrid resins were readily realized by melt blending of ethynylpolyimide and phenylacetylene-terminated polysilylarylacetylene (BLJ). The results reveal that the hybrid resin has a low melting point (<80℃), the improvement of rehological behaviors and processing capability of Resin Transfer Molding (RTM). Furthermore for the ethynylpolyimide hybrid (with BLJ), the thermal cure temperature was highly decreased (about 125~170℃), and the thermal resistance in air was enhanced (mass loss less than 5% affter heat-treated at 500℃ for 10 min in air). The mechanical properties of laminates with silica cloth as reinforcement at high temperature were comparably ideal, and the glass transition temperature (T_g) is less than 350℃. The ethynylpolyimide-polysilylarylacetylene hybrid resin is a kind of promising candidate for thermo-structure materials in aerospace and aviation indusries.