DEFORMATION AND ENTANGLEMENT IN SEMICRYSTALLINE POLYMERS

Transmission electron microscopy and optical studies of thin films of isotactic polystyrene (iPS) and polyoxymethylene (POM) provide evidenc e for a distinction between crazing mechanisms in semicrystalline poly mers above and below T(g). In the latter temperature regime, deformati on in iPS and POM crystallized at high supercooling has been discussed in terms of existing models for crazing in amorphous glassy polymers, based on entanglement ideas. Above T(g), where the difference in mech anical behavior of the amorphous and crystalline regions becomes marke d, the fibrillar nature of local deformation appears to be a consequen ce of the inhomogeneity of the undeformed polymer.