Morphology-Property Relationships in Polymers: Poly(vinyl Chloride) and Polybutene-1 (Polyvinyl)
Yang, Yung-Chin
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https://hdl.handle.net/2142/71799
Description
Title
Morphology-Property Relationships in Polymers: Poly(vinyl Chloride) and Polybutene-1 (Polyvinyl)
Author(s)
Yang, Yung-Chin
Issue Date
1982
Department of Study
Metallurgy and Mining Engineering
Discipline
Metallurgical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Abstract
Solid state PVC processed by various methods were characterized. The (as polymerized) virgin polymer is higher in crystallinity than following normal melt processing. Crystallinity determined by x-ray and Fourier transform infrared (FTIR) is in good agreement when appropriately calculated. Two exothermic and two endothermic peaks are observed in the differential scanning calorimeter (DSC) scans, the intensity varying as a function of melt temperature, quenching rate, aging and compression during processing; the processing history can be characterized by the DSC spectrum. Two kinds of crystals which behave differently from each other in deformation can be prepared through various methods. Models for the two types of crystals were proposed. The tensile properties depend on the degree of crystallinity and type of crystals. Four PVC/solvent gels (PVC/Dimethyl phthalate, PVC/Bromobenzene, PVC/Dioxane and PVC/Dichloroethane) were characterized. The crystal melting temperatures in the gels were found to be different from the gel melting temperatures. The melting enthalpy of these gels are in the vicinity of the hydrogen bonding energy. The number of molecules involved per junction in the gel was determined to be two. Molecular entanglement and hydrogen bonding rather than crystal formation is suggested to be responsible for gel formation. Gel forming ability and gel hardness was found to be determined by polymer-solvent interaction. Crystals grow in the gel phase after gel formation as observed by DSC and FTIR. Freeze-fracture, freeze-etch microscopy suggests that PVC molecules aggregate while forming the gel to form a network-like structure. Melt-crystallized PB-1 consists of spherulites which are composed of ca. 200 (ANGSTROM) thick ribbons. The II (--->) I phase transformation is suggested to occur by growth along the ribbons. The transformation is accelerated by plasticizing liquid and by tensile deformation. The tensile properties depend on the crystal form and deformation rate. IR band frequency shifts were observed in PB-1 during aging and deformation. Blocks (mosaic) and inter-crystallite tie-molecules are observed in deformed PB-1 by electron microscopy. Deformation proceeds differently with respect to the relative direction between the molecular axes in crystals and the deformation direction. A morphological model of PB-1 deformation process is proposed.
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