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|Title:||Structure and Property of Polybutylene, Polypropylene and Polyvinylidene Fluoride Crystallized From the Glassy State and Structure-Property - Processing Relationships of Polypropylene - Polybutylene Blends|
|Department / Program:||Metallurgy and Mining Engineering|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Ultraquenching was used to obtain glassy polybutylene (PB), polypropylene (PP) and polyvinylidene fluoride (PVF(,2)). The structure and properties of the as-quenched and subsequently crystallized samples were characterized by various techniques. The glass has no structure larger than 30 (ANGSTROM). PB crystallizes from the glass into tetragonal structure (II) at ca. 0(DEGREES)C, depending on the sample thickness, then transforms to twinned hexagonal structure (I) upon aging at room temperature. In the presence of isopentane, PB crystallizes partially from the glass into untwinned hexagonal (I') structure at ca. -100(DEGREES)C, the rest of the sample transforms to tetragonal structure at ca. 0(DEGREES)C. The exact temperatures of both transformations depend on the amount of isopentane present and sample thickness. Upon aging at room temperature the tetragonal structure converts to twinned hexagonal structure even faster than in the absence of isopentane. Dynamic mechanical spectra show the presence of two relaxation-like peaks at -27(DEGREES)C and -15(DEGREES)C for the ultraquenched samples, presumably T(,g)(L) and T(,g)(U) respectively. X-ray diffraction, DSC and torsion pendulum show PB crystallizes from the glass at T(,g)(U).
PP crystallizes from the glass into a nodular, smectic structure (80 - 100 (ANGSTROM) diameter) at ca. -20(DEGREES)C and then transforms to monoclinic microcrystals at ca. 40(DEGREES)C. Annealing above T(alpha) results in the formation of short fibers. Dynamic mechanical spectra also suggest the presence of two T(,g)s for the as ultraquenched samples, T(,g)(L) = -10(DEGREES)C and T(,g)(U) = 10(DEGREES)C. Crystalization from the glass occurs at T(,g)(L).
For PVF(,2), electron diffraction indicates crystallization from the glass at ca. -35(DEGREES)C into the form. Dynamic mechanical spectra indicate the existence of two T(,g)s for both air quenched and ultraquenched samples. For the air quenched samples T(,g)(L) = -40(DEGREES)C and T(,g)(U) = 30(DEGREES)C; for the ultraquenched samples T(,g)(L) = -38(DEGREES)C and T(,g)(U) is between 0(DEGREES)C and 55(DEGREES)C. Rapid crystallization from the glass results in the development of a nodular, microcrystalline morphology which can only be changed by annealing above T.
Blends of PP and PB were prepared by either melt mixing or solution mixing followed by ultraquenching. The crystallization behavior of the blends from the melt and glass, and the resulting morphology and physical properties were characterized by different methods. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
|Date Available in IDEALS:||2014-12-16|
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Dissertations and Theses - Metallurgy and Mining Engineering
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois