THE MECHANICS OF SPHERULITE DEFORMATION.
MASSACHUSETTS UNIV AMHERST POLYMER RESEARCH INST
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The deformation of both tetragonal fresh film and hexagonal aged film modifications of polybutene-1 spherulites have been studied. The deformations were introduced by uniaxial stretching. The local birefringence of different regions of individual spherulites has been found to be different and its change with strain also varies between the crystalline modifications. Morphological changes with strain are illustrated by microphotographs. The rotation of the maltese extinction cross toward the stretching direction can be accounted for by the rotation of the optic axis toward the stretching direction. Void formation is very pronounced in the hexagonal modification and negligable in that of the tetragonal. Model calculations of birefringences give results agreeing with the experimental values. Finally, the affine deformation behavior was investigated by photographically measuring the changes in spherulitic areas. The changes in shapes of deformed spherulites are shown by interference microscopy and microscopy using polarized light on cross-sections obtained by microtoming. The affine deformation theory has been found to be valid only in low degrees of deformation. Author