Temperature dependence of craze shape and fracture in poly(methyl methacrylate)

The shape of the craze at the tip of a slowly moving crack has been determined by optical microscopy for poly(methyl methacrylate) over the range of temperatures ?30° to +45°C. In all cases the craze shape can be described by the Dugdale model for the plastic zone at a crack tip. It was of particular interest that the crack opening displacement was found to be constant over the whole temperature range. Fracture toughness values deduced from the craze shape were in good agreement with those obtained directly. Quantitative estimates of the craze stress were obtained and are discussed.