共聚序列结构对生物基共聚尼龙5T/56非等温结晶动力学影响

Effect of Copolymerization Sequence Structure on Non-isothermal Crystallization Kinetics of Bio-based Copolymer PA 5T/56

以生物基单体戊二胺为原料,分别制备无规共聚和嵌段共聚尼龙(PA5T/56)。通过核磁共振波谱仪对其进行了结构表征,采用差示扫描量热仪研究其共聚体系的非等温结晶行为。分别用Ozawa方程、Jeziorny方程、莫志深法进行非等温结晶动力学分析。Ozawa方程分析结果表明,结晶过程中晶核生长方式具有温度依赖性,晶核生长方式随温度升高而复杂化。无规共聚PA 5T/56的结晶过程更为复杂,晶体生长方式更多维。Jeziorny方程分析结果表明,无规共聚PA5T/56的结晶速率更高,结晶更完善。且共聚体系仅在主结晶期对该拟合方程具有良好的线性关系,结晶后期偏离拟合直线方向。莫志深法分析结果表明,同一相对结晶度下,无规共聚PA5T/56体系的结晶速率较嵌段共聚体系更高。通过Kissinger方程计算得到无规共聚PA5T/56和嵌段共聚PA5T/56的活化能分别为-311.23kJ/mol,-168.88k J/mol,表明无规共聚PA5T/56较嵌段共聚PA5T/56具有更高的平均结晶速率,更强的结晶能力。

The PA5T/56 with random copolymerization and block copolymerization were prepared based on the bio-based monomer 1,5-pentanediamine.The structures of PA5T/56 were characterized by nuclear magnetic resonance.The non-isothermal crystallization behavior of PA5T/56 was studied by differential scanning calorimetry.Ozawa equation,Jeziorny equation and Mo equation were used to describe the non-isothermal crystallization kinetics.The Ozawa equation results show that the growth mode of crystal nucleus is temperature-dependent and the growth mode of crystal nucleus becomes complicated with the increase of temperature.The crystallization process and crystal growth mode of random copolymer PA 5T/56 are more complex and multidimensional than that of block copolymer.The results of Jeziorny equation show that the crystallization rate of random copolymer PA5T/56 is higher and the crystallization is more perfect.In addition,the copolymerization system has a good linear relationship with the fitting equation only in the main crystallization stage,and deviates from the fitting straight line in the later stage of crystallization.Mo method indicate that the crystallization rate of random copolymer PA5T/56 system is higher than that of block copolymer system under the same relative crystallinity.The activation energies of random copolymerization and block copolymerization PA5T/56 calculated by Kissinger equation are-311.23 kJ/mol and-168.88 kJ/mol respectively,which indicate that random copolymer PA5T/56 has higher average crystallization rate and stronger crystallization ability than block copolymer PA5T/56.