Mobile amorphous, rigid amorphous and crystalline fractions in isotactic polypropylene during fast cooling

详细信息    查看全文

• 作者：Jürgen E. K. Schawe
• 关键词：Polypropylene ; Crystallization ; Rigid amorphous fraction ; Glass transition ; Fast scanning calorimeter
• 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：931-937
• 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

Crystallization of isotactic polypropylene was analyzed by fast scanning calorimetry (Flash DSC) at cooling rates between 1 and 4000 K s−1. By quantitative analysis of the glass transition intensity and the specific transformation enthalpy, the amount of mobile amorphous (MAF), rigid amorphous (RAF) and crystalline fractions (CFs) and its dependency on the cooling rate were determined. During cooling, two different crystalline phases are formed. At slow cooling rates (below 90 K s−1), the α-phase is crystallized. At faster cooling rates mesophase aggregates are formed. The crystalline phase reduces the relaxation time in the MAF independently from the kind of the crystalline phase. The RAF is formed during the crystallization process. In the case of mesophase crystallization, the ratio between CF and RAF is independent of the crystallinity. For α-phase crystals, this ratio depends on the crystallinity. A model for the CF-RAF structure is derived from the reported results.