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QUANTITATIVE SMALL-ANGLE LIGHT SCATTERING STUDIES OF SEMI-CRYSTALLINE POLYMERS (POLYETHYLENE TEREPHTHALATE, POLYPROPYLENE)
Abstract
This dissertation presents studies of the advancement and utilization of the techniques of small-angle light scattering (SALS) to investigate the morphology of deformed and undeformed spherulitic semicrystalline polymers. The technique advancements were made in the theoretical and instrumental aspects of SALS. The utilization of the latest techniques was made in four experimental SALS studies. The major theoretical advancement of SALS made in this work was the determination, by computer simulation, of the effects of spherulitic truncation on H(,v) SALS. The changes in the H(,v) SALS patterns and equations due to these effects were determined. The method can be readily extended to the SALS study of several other morphological phenomena. The major instrumental advancement made in this work was the development of a position sensitive SALS detector system. The device allows one to rapidly collect and analyze quantitative, two dimensional SALS data, which is essential to this and many other studies of polymers by SALS. In a study of the melting of polyethylene terephthalate (PET), it was found that the spherulites melt over a range of about 20(DEGREES)C without change in spherulite size, number or internal disorder. In a study of PET crystallization, it was found that, as the spherulites grow, there was an initial decrease and then a levelling off of both the internal disorder and the spherulite crystallinity. The quantitative H(,v) SALS intensities, corrected for experimental and internal and external disorder effects, were in moderate agreement with those calculated from the sample crystallinities, for both the melting and the crystallization studies. It was found in a study of low density polyethylene (LDPE) and polypropylene (PP) elongation that the van Aartsen and Stein affine model of spherulite deformation described the H(,v) SALS of LDPE and PP, but failed in the description of V(,v) and H(,h) SALS. The deformation mechanisms indicated by the H(,v) SALS were reasonable for LDPE and PP. It was found, and explained in terms of the Debye-Bueche theory, that the haze from films of phase separated polymer blends does not increase monotonically with the size of the phase separated particles.
Subject Area
Polymers
Recommended Citation
TABAR, RONALD J, "QUANTITATIVE SMALL-ANGLE LIGHT SCATTERING STUDIES OF SEMI-CRYSTALLINE POLYMERS (POLYETHYLENE TEREPHTHALATE, POLYPROPYLENE)" (1983). Doctoral Dissertations Available from Proquest. AAI8317495.
https://scholarworks.umass.edu/dissertations/AAI8317495