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Crystallization and Structure Relationship of Polyolefin-based Polymers under Static and Flow Conditions

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dc.contributor.advisor Hsiao, Benjamin S en_US
dc.contributor.advisor Chu, Benjamin en_US
dc.contributor.author Li, Xiaowei en_US
dc.contributor.other Department of Chemistry. en_US
dc.date.accessioned 2017-09-20T16:52:01Z
dc.date.available 2017-09-20T16:52:01Z
dc.date.issued 2013-12-01 en_US
dc.identifier.uri http://hdl.handle.net/11401/77122 en_US
dc.description 162 pg. en_US
dc.description.abstract Polyolefins have played an important role in human society, partially due to wide applications, such as their extensive use in packaging films, cables, wires, bags, containers, and appliances. Therefore, it becomes a worthwhile undertaking to investigate and to improve their properties, which can reduce cost and decrease pollution to the environment. Polyethylene (PE) and Polypropylene (PP) take a large role in polyolefin products. They occupy more than half of the thermoplastic market. They are semi-crystalline polymers with a relatively high degree of crystallinity. The crystal structure is an important factor that should be considered as they are closely related to the material performance. Both the characteritics of the starting material and the processing steps have significant effects on the crystal structure and subsquent materials properties. In this thesis, the crystallization and structure relationship of polyethylene- and polypropylene-based materials, including pure polymer, blend and copolymer, were studied. <italic>In-situ</italic> Wide angle X-ray Diffraction (WAXD) and Small angle X-ray Scattering (SAXS) were performed during different processing steps, i.e., under static and flow conditions. A single cell heating stage was used for studying the static crystallization behavior of polyolefin-based materials under different thermal conditions. Isothermal crystallization of high-density polyethylene/silica (HDPE-SiO<sub>2</sub>) at different SiO<sub>2</sub> loadings showed that SiO<sub>2</sub> behaved as crystal nucleus in the blend samples. Different instruments were used to study the structural changes during different processing steps. A specially designed cross-slot flow cell device was applied to generate extension-dominant flow and its influence on the crystallization behavior of isotactic polypropylene (iPP). A modified tensile stretching machine that allowed symmetrical stretching of the film was used to investigate the structural change during stretching and their relationship with mechanical performance. Ionic liquid (IL) and ultra-high molecular weight polyethylene (UHMWPE) blend prepared by solution mixing showed a significant increase in the elongation-to-break ratio. For propylene-1-octene random copolymers with higher octene content, the elastic modulus and the yield stress were decreased. Then, they behaved more like elastomers. en_US
dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US
dc.format Monograph en_US
dc.format.medium Electronic Resource en_US
dc.language.iso en_US en_US
dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US
dc.subject.lcsh Polymer chemistry en_US
dc.subject.other Crystallization, Polyethylene, Polyolefin, Polypropylene, Structure en_US
dc.title Crystallization and Structure Relationship of Polyolefin-based Polymers under Static and Flow Conditions en_US
dc.type Dissertation en_US
dc.mimetype Application/PDF en_US
dc.contributor.committeemember Grubbs, Robert en_US
dc.contributor.committeemember Wong, Stanislaus en_US
dc.contributor.committeemember Tsou, Andy. en_US

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