Fractographic Analysis of Interlaminar Fracture
SourceThe failed surfaces of interlaminar fracture (Mode I) specimens were examined using scanning electron microscopy. The matrix resins were Hercules 3501-6 and 2502 epoxys and Phillips Petroleum polyphenylene sulfide (PPS) and the reinforcing carbon fibers were Hercules AS4 and AS6G. The epoxy matrix composites exhibited fiber pull-out, hackle markings, and regions of smooth resin fracture. Considerable (30 to 50%) relaxation of the deformed resin occurred when the epoxy matrix specimens were heated above the matrix glass transition temperature Tg. Some of the fractography features are discussed in terms of transverse tensile stresses and peeling stresses acting on the fibers. The PPS/AS4 fracture surfaces were characterized by large amounts of apparent interfacial failure at the fiber-resin boundary and massive deformation of the PPS matrix.