FRACTURE AND CRAZING OF POLYMERIC MATERIALS UNDER PLANE-STRAIN

To specify brittle fracture of polymers under a state of plane strain deformation, tensile, bending and indentation tests were carried out for polycarbonate, poly (vinyl chloride), poly (methyl methacrylate), polystyrene, acrylonitrile-styrene copolymer, nylon, polyethylene and polypropyrene. Morphological observations revealed that fracture nuclei were initiated at the elastic-plastic boundary where a hydrostatic stress component was highest. Eventually, brittle fracture occurred by growth of the craze around the nuclei. A slip-line field theory allows the determination of the critical hydrostatic stress for fracture from the knowledge of the location of the nuclei. The extent to which the theory can be used to calculate the stress components was checked so that the yielding of polymers was influenced by the hydrostatic pressure. © 1979, The Society of Polymer Science, Japan. All rights reserved.