SURFACE CHEMICAL MODIFICATION OF GRAPHITE FILAMENTS TO IMPROVE GRAPHITE/THERMOPLASTIC COMPOSITES

PLASMA AMINATION WAS SUCCESSFULLY APPLIED TO LOW AND INTER- MEDIATE MODULUS GRAPHITE FIBERS. AMINE CONCENTRATION DENSI-TIES EXCEEDED 1.6 AND 0.6 NH2/100A2, RESPECTIVELY. AMMONIA PLASMA EXPOSURE INDUCED NO DAMAGE IN LOW MODULUS FIBERS; INTERMEDIATE MODULUS WERE NOT TESTED. PEEL STRENGTH OF AN AS4/EPOXY MAY HAVE BEEN ENHANCED BY PLASMA TREATMENT. TRANSVERSE TENSILE STRENGTH OF A UNIDERECTIONAL IM6/EPOXY WAS IN-CREASED 65%. STRENGTH INCREASES ARE ATTRIBUTED TO DEVELOP- MENT OF COVALENT BONDS AT THE INTERFACE. FOR NON-REACTIVE POLYMERS, PLASMA PROCESSES CAN INCREASE INTERFACIAL ADHESION THROUGH SURFACE CHEMISTRY MODIFICATION,TAILORING SURFACE ENERGETICS TO STRENGTHEN SECONDARY BONDINGGIVEN THE LOW INTERFACIAL ADHESION WHICH AFFECTS HIGH PER- FORMANCE FIBERS IN THERMOPLASTICS, THIS IS A CRITICAL NEED. IMPROVED SECONDARY BONDING (I.E., ACID-BASE INTERACTIONS) WILL BE INVESTIGATED FOR INTERMEDIATE AND HIGH MODULUS GRAPHITE FIVERS AND TWO THERMOPLASTICS, POLY (PHENYLENE OXIDE) AND POLYCARBONATE. SURFACE ENERGY STATE IF THE GRAPHITE WILLBE MODIFIED BY HDROGEN PLASMA (I.E., REDUCTION) AND OXYGEN PLASMA (I.E., ACIDIC). SURFACE ENERGETICS TAILORING WILL BECONDUCTED WITH AS-RECEIVED THERMOPLASTICS. ACID-BASE INTER-ACTION WILL BE STRENGTHENED BY PLASMA AMINATION OF THE THER-MOPLASTICS (I.E., BASIC). INTERACTION WILL ULTIMATELY BE EXTENDED TO STRONG ACIDS AND BASES.