Syndiotactic Polystyrene: Crystals, Morphology, Crystallization Kinetics and Induced Changes
碩士 === 國立成功大學 === 化學工程研究所 === 85 === The crystalline, morphology, crystallization kinetics and induced changes of two syndiotactic polystyrene-based blends (s-PS/a-PS and s-PS/PPO) were studied and determined. s-PS presents a very complex polymorphic morphologies, with four different crystalline...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
1997
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| Online Access: | http://ndltd.ncl.edu.tw/handle/97960476338047387081 |
| Summary: | 碩士 === 國立成功大學 === 化學工程研究所 === 85 ===
The crystalline, morphology, crystallization kinetics and induced changes of two syndiotactic polystyrene-based blends (s-PS/a-PS and s-PS/PPO) were studied and determined. s-PS presents a very complex polymorphic morphologies, with four different crystalline forms identified so far. The structure and morphology of s-PS and its blends were investigated using wide angle X-ray scattering diffractometer (WAXD) and differential scanning calorimetry (DSC); The literature shows that a mixture of the α、β and β' form is present in pure s-PS annealed sample. The relative intensities of these forms changed with the crystallization temperature(Tc), with Tc above 250℃ that favoring the attainment of the β form . Blending s-PS with PPO or a-PS was to found to favor the P form in these blends. The DSC melting curve also indicated same results, whuch shows one endotherm peak of a form and two endotherm peaks of f3 form. Isothermal spherulitic growth rates of s-PS and its blends with a-PS or PPO were determined over a range of crystallization temperature using polarized-light microscopy and a hot stage. The spherulite growth rate of s-PS decreased as the PPO(or a-PS) volume fraction was increased. The Avrami equation was used to analyse the data of the bulk kinetics of crystallization. The values of the Avrami index (n) range between 2∼3. indicating mixed crystallization and nucleation mechanisms. The Avrami rate constants (k) decreased with increasing crystallization temperature.
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