Effect of Interfacial Adhesion of Polycarbonate Film on Mode I and II Fracture Toughness of Interleaved Epoxy Composites

Abstract

Polycarbonate (PC) films were used to interleave bi-directional glass fiber (GF) weave/epoxy composites to study the effect on mode I and mode II interlaminar fracture toughness. Films of PC with smooth and textured surface finish and oxygen plasma treatment were used to examine the effect of interfacial adhesion between the epoxy and PC film on composite toughening. The standard double cantilever beam (DCB) and end notched flexure (ENF) tests were used for mode I and II interlaminar fracture toughness characterization respectively, considering both neat and interleaved laminates. Results indicate an increase up to 59% in mode I interlaminar fracture toughness for interleaved GF/epoxy composites with textured surface PC films. Morphological observations of fractured DCB surfaces indicate that the improved toughness in the case of textured PC film interleaves is related to surface roughness, promoting cohesive-adhesive failure of the film due to better interfacial adhesion of PC film and epoxy matrix. Furthermore, the results of ENF tests indicate that the PC films can also enhance mode II interlaminar fracture toughness of GF/epoxy composites by 42% in the case of oxygen plasma treated PC films. Additionally, dynamic mechanical analysis of PC interleaved composites showed that high operational temperature can be preserved in the interleaved composites.