Self-nucleation and crystallization of polyvinyl alcohol
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- 作者：David Thomas ; Peggy Cebe
- 关键词：Polyvinyl alcohol (PVA) ; DSC ; Thermogravimetric analysis ; Self ; nucleation
- 刊名：Journal of Thermal Analysis and Calorimetry
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：127
- 期：1
- 页码：885-894
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Physical Chemistry; Analytical Chemistry; Polymer Sciences; Inorganic Chemistry; Measurement Science and Instrumentation;
- 出版者：Springer Netherlands
- ISSN：1588-2926
- 卷排序：127
文摘
Polyvinyl alcohol (PVA) is a hydrophilic, biodegradable, semicrystalline polymer with a wide array of commercial uses ranging from textiles and packaging to medicine. Film samples of PVA were investigated to assess crystallization and melting behavior during self-nucleation experiments and thermal degradation, using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis, respectively. TG results show that degradation occurred at temperatures in excess of 200 °C which is close to the observed peak melting temperature of 223 °C. PVA was heated to various self-nucleation temperatures, Ts, within its melting range, and then cooled and reheated. Three distinct crystallization regimes were observed upon cooling, depending upon the self-nucleation temperature (Ts) selected. At low values of Ts, Ts < 227 °C, PVA only partially melts, and upon cooling the residual crystals anneal and become more stable. At intermediate values of Ts, 228 °C < Ts < 234 °C, PVA was found to crystallize exclusively from self-nucleation. For Ts > 235 °C, the PVA melts completely and absence of self-nucleation sites causes crystallization to occur at lower temperatures.