Improved Kinetic Model of Crystallization for Isotactic Polypropylene Induced by Supercritical CO2: Introducing Pressure and Temperature Dependence into the Avrami Equation
Improved Kinetic Model of Crystallization for Isotactic Polypropylene Induced by Supercritical CO2: Introducing Pressure and Temperature Dependence into the Avrami Equation
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DOI：
10.1021/ie101638b
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发表时间：
2011-08
影响因子：
4.2
通讯作者：
Renshi Zhang;Xue‐Kun Li;G. Cao;Yun-hai Shi;Honglai Liu;W. Yuan;G. W. Roberts
中科院分区：
文献类型：
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作者：
Renshi Zhang;Xue‐Kun Li;G. Cao;Yun-hai Shi;Honglai Liu;W. Yuan;G. W. Roberts
超临界二氧化碳（SC-CO2）提供了一种高度可调的技术，以诱导各种聚合物的形态和结晶动力学的变化。采用差示扫描量热法（DSC）研究了超临界CO2处理对等规聚丙烯（i-PP）结晶度的影响。Avrami方程适用于描述各种固体的结晶动力学。然而，结晶度随着时间接近无穷大而接近1.0的假设对于半结晶聚合物是不成立的，特别是在SC-CO2气氛中。通过在Avrami方程中引入平衡结晶度以及温度和压力相关项，提出了一种改进的CO2诱导异相聚丙烯结晶动力学模型。通过对DSC数据的最小二乘拟合，得到了结晶动力学模型的参数。结果表明，改进后的动力学模型能较好地描述异相聚丙烯在不同温度下的结晶行为。
Supercritical carbon dioxide (SC-CO2) provides a highly tunable technique to induce changes in morphology and crystallization kinetics of various polymers. In this study, the effect of SC-CO2 treatment on the crystallinity of isotactic polypropylene (i-PP) was analyzed by differential scanning calorimetry (DSC). The Avrami equation is suitable for describing crystallization kinetics of various solids. However, the assumption that the crystallinity approaches 1.0 as the time approaches infinity is not valid for semicrystalline polymers, especially in the atmosphere of SC-CO2. An improved kinetic model for the CO2-induced crystallization of i-PP was purposed by introducing equilibrium crystallinity, as well as temperature- and pressure-dependent terms into the Avrami equation. The parameters of the crystallization kinetics model were obtained by least-squares fitting of the DSC data. The results show that the improved kinetic model provides a reasonable description of the crystallization behavior of i-PP in...