Some molecular aspects of craze formation

Summary The changes in molecular orientation occurring during craze initiation and growth are discussed. Craze initiation is considered as a stress-induced, rotational, collective reorganisation of stiff chain sections in volume elements having a particularly large compliance. An energy balance is established for the transformation of a partially oriented matrix into craze fibrils which relates the fibril diameter to fibrillation stress and surface energy parameters. The predicted dependence of fibril diameter on temperature and preorientation is confirmed by experiments on polycarbonate.Dedicated to C. C. Hsiao and J. A. Sauer on the occasion of the 30th anniversary of the publication of their paper: On Crazing of Linear High Polymers