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The effect of surface treatment of pitch-based carbon fiber on a new engineering thermoplastic resin, polyethernitrile, was investigated. Pitch-based carbon fiber (CF) was treated in two separate oxidizing solutions. In the first method, a nitric acid solution was used as a n oxidizing agent. In the second method, a hydrogen peroxide solution was used. Both methods demonstrated that each of these solutions was a satisfactory oxidizing agent for the pitch-based CF. These treated fibers were combined with polyethernitrile polymer by the powder impregnation method, and unidirectional laminates were obtained. Improvements in both interlaminar shear strength and transverse flexural strength were achieved. The laminates fabricated from the treated CF maintained the same longitudinal flexural strength a s laminates from the untreated control. In addition, scanning electron micrographs of composite fracture surfaces also showed excellent bonding of the treated fiber.

SynopsisPolybutadiene ionene (PBI) carrying quaternary ammonium ions in the main chain was synthesized from dimethylamino-terminated polybutadiene and 1,4-dibromobutane. Dimethylamino-terminated polybutadiene was prepared by the reaction of isocyanate-terminated polybutadiene with 2-dimethylaminoethanol. The swelling property and the mechanical properties of PBI were compared with those of polybutadiene urethane (PBU), which was prepared by the reaction of hydroxy-terminated polybutadiene with a diisocyanate. The following points were found: (1) PBI shows almost the same solubility parameter Sp as that of PBU; (2) PBI attains a four time greater tensile strength at break than PBU at room temperature; (3) PBI shows a thermoplastic behavior.

A new engineering thermoplastic resin (ID300) was combined with continuous carbon fiber (CF) to produce an advanced composite material. Both polyacrylonitrile (PAN) and pitch-based carbon fiber were investigated as reinforcements. Impregnation was accomplished directly from the powder form to a well-consolidated prepreg sheet. No fiber degradation even for the pitch carbon-fiber system was experienced. The mechanical properties measured included flexural strength, compressive strength and short beam shear strength.The ID300 materials compare quite favorably to conventional thermoplastic and thermoset material systems. The prepreg sheet was utilized in the diaphragm sheet forming method to produce hemispherical geometries from laminates of [0/90] s and [0/45/-45/90] s configurations. The laminates exhibited excellent formability