The crystallization of poly(ethylene oxide) (PEO) in blends with amorphous poly(vinyl chloride) (PVC), in a mixture with the PVC-selective plasticizer tricresyl phosphate (TCP), and in ternary mixtures with both PVC and TCP has been investigated at several structural levels using the techniques of: (i) theoretical surface interfacial tension calculations, (ii) thermal analysis, (iii) polarized light microscopy, and (iv) polarized infrared microspectroscopy. / The invariance of the glass transition temperature of the interlamellar, amorphous PEO suggests a relatively low degree of dispersion in PEO/PVC blends. A slight depression in the equilibrium melting temperature of PEO in blends of high PVC content was observed, and subsequent analysis of the data using the Flory-Huggins equation reveals that, at best, PEO and PVC exhibit limited miscibility in the melt. The melting temperature depression may be accentuated by the addition of TCP, but the depression observed in the ternary mixtures lies within the experimental uncertainty. / In general, the spherulites grown in the presence of additives are coarser and less birefringent than those grown in the pure melt, with the degree of coarseness increasing with increasing additive concentration. The interpretation of the crystallization kinetics of PEO using current nucleation theory clearly demonstrates that the crystallization of PEO in the temperature range of interest occurs within regime III. The slight kinetic discontinuity at $ sim$51$ sp circ$C that has been thought to arise from a regime II/III transition can be attributed to a transformation of the dominant crystal growth face from the (010) crystallographic face at lower temperatures to the (120) face at higher temperatures. The growth rates of PEO spherulites in PEO/PVC blends are not affected by the presence of PVC in the temperature range 49-55$ sp circ$C, even at concentrations as high as 50% PVC. However, the growth rates of spherulites in mixtures containing TCP are significantly depressed. / Dichroic infrared microspectroscopy was employed to investigate the variations in the crystalline structure at the sub-spherulitic level. The determination of the dichroic ratios and the selected peak ratios from the spectra of purely crystalline PEO (obtained by difference spectroscopy) reveals that PVC disturbs the orientation of the crystalline stems of PEO within the spherulites and causes an increase in the crystallization of PEO in the strained, planar zig-zag conformation. PEO, in turn, appears to induce a higher incidence of the planar zig-zag conformation in the PVC molecules. In the ternary mixtures, the plasticizing effect of TCP on PVC renders the PVC molecules more flexible and more mobile, thereby drastically reducing the shearing of the PEO and the resultant formation of the planar zig-zag conformation during crystallization. In effect, the crystallization kinetics and the basic crystalline structure of PEO can be controlled by selection of appropriate proportions of PVC and TCP, a result of major significance and practical importance to the field of polymer blends.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.29082 |
| Date | January 1995 |
| Creators | Marentette, Joanne M. (Joanne Marie) |
| Contributors | Brown, G. Ronald (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001474237, proquestno: NN08132, Theses scanned by UMI/ProQuest. |
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