The Mechanism of Crazing in Polystyrene
CASE WESTERN RESERVE UNIV CLEVELAND OHDEPT OF MACROMOLECULAR SCIENCE
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The craze initiation and growth process in thin films of polystyrene has been studied via electron microscopy. Inhomogeneity in the surface microstructure gave rise to the formation of c.a. 300A nuclei in which large strains were localized. These randomly distributed nuclei were formed at the glass transition temperature in the presence of bulk shear deformation. A disk shaped microneck zone was ultimately formed by coalescence of these nuclei which was followed by cavitation and fibrillation of this zone at a critical internal hydrostatic tension. Cavity and fibril stability increased with molecular weight above the entanglement molecular weight.