EFFECT OF TRANSCRYSTALLINITY ON TENSILE BEHAVIOR OF DISCONTINUOUS CARBON-FIBER-REINFORCED SEMICRYSTALLINE THERMOPLASTIC COMPOSITES

Short carbon fibre reinforced polyetheretherketone (PEEK) composites w ith and without transcrystalline interphase are prepared under differe nt conditions, and are used to investigate the effect of transcrystall ine interphase on the tensile behaviour of semicrystalline thermoplast ic polymer based composites. Volume dilatometry and scanning electron microscopy (SEM) are also employed as supplementary means. It is found that the formation of transcrystalline interphase improves such impor tant characteristics of the composites as tensile stiffness, strength and toughness. The transcrystalline interphase enhances fibre-matrix a dhesion and reduces stress concentration and cavitation at the fibre e nds. The predominant deformation mechanism of the composite is changed from cavitation to shearing process in the presence of transcrystalli ne interphase, and moreover, significant local plastic deformation tha t absorbs more energy occurs, resulting in cohesive failure of the com posite instead of adhesive failure happening to the composite without transcrystalline interphase. Copyright (C) 1996 Elsevier Science Ltd.