Surface morphology of polystyrene fractured in liquids

Polystyrene test pieces broken by flexure in the presence of n-propanol and other alcohols have been examined by scanning electron microscopy. Two regions on the fracture surface are observed; a narrow band near to the tension surface corresponds to fracture through a solvent craze, but the remainder of the surface is identical to fracture surfaces produced in air. The solvent-crazed region has a cellular structure decreasing in scale toward the tip of the craze. An explanation of these features is offered in terms of the changing conditions of stress and solvent content ahead of the growing craze.