The Toughness and Morphology Spectrum of Bismaleimide/Polyetherimide Carbon Fabric Laminates

The paper describes the fracture energy (G_1c) spectrum of bismaleimide (BMI)/thermoplastic polyetherimide (PEI) carbon fabric laminates. The PEI concentration was varied between 0% and 100% by weight. Only negligible G_1c improvements were obtained for BMI/PEI matrices with 30% or less PEI content. This was probably due to the fact that the large PEI/BMI clusters are concentrated in the crossover regions between the warp and fill strands of the fabric. BMI/PEI matrices with 40% or more PEI content show the expected neat resin/composite G_1c correlation in that an increased PEI content improves the toughness of both laminate and neat resin because the morphology of the neat resin and laminate are similar. Poor phase adhesion between BMI and PEI was used to explain mechanical property losses for BMI/PEI fabric laminates with low BMI content.