Strain-Rate Effect on Tensile and Fracture Behaviors of Phenylethynyl Terminated Imide Oligomer-5 (PETI-5)

Abstract

Tensile and fracture responses of phenylethynyl terminated imi de oligomer 5-th composition (PETI-5) are studied. Since this polymer serves as an adhesi ve and as a matrix material in composite systems, neat as well as fiber-reinforced forms of PETI-5 are studied under static and dynamic loading conditions. A split-Hopkinson tension bar apparatus is used for dynamic tensile testing on dogbone specimens. The dynamic fracture tests are carried out using 2D digital speckle correlation method and high-speed photography on impact loaded edge-cracked specimens in 3-point bend configuration. Another commonly used epoxy system, EPON 828, is also studied to provide a baselin e comparison. The tensile stress-strain responses show PETI-5 to have excellent mechanical characteristi cs under quasi-static and dynamic loading conditions relative to EPON 828. Fracture behavior under quasi-static and impact loading conditions again shows superior fracture pa rameters relative to EPON 828. The dynamic fracture behavior of a graphite fiber reinforced co mposite system, IM7/PETI-5, is also studied and the results are comparatively evaluated for two fiber orientations. Once again, the IM7/PETI-5 system shows excellent fracture properties in terms of various fracture parameters such as crack initiation toughness, crack speed, fracture surface morphology, and among others.