Abstract：Single and pauci chain aggregates of isotactic polystyrene (i-PS) were prepared by the freeze-drying process from dilute solutions with the concentration from 1?10-3 to 2?10-5 g/mL. It was found by DSC measurements that the melting point of samples gradually shifted to lower temperatures with the decrease of the solution concentration used for sample preparation. As a result, the lamella thickness of bulk samples and the samples prepared by the freeze-drying process from a solution of 2?10-5 g/mL was 19.3 and 12.6 nm, respectively. At 468.3 K the half crystallization time (t1/2) of samples freeze-dried from a solution of 1?10-4 g/mL was about 36 s, which was merely one tenth of that of the bulk sample. In addition, the growth rate of spherulite (dr/dt) of samples prepared from a solution of 2?10-5 g/mL was faster than that of the bulk sample annealed at 478.3 K. All these results should be attributed to the fewer entanglements in samples prepared by freeze-drying process from dilute solutions, and presented clear evidence for the influence of chain entanglements on the crystallization behavior of polymers.
出版日期: 2006-12-05
引用本文:
. Crystallization behavior of single or pauci chain aggregates of isotactic polystyrene[J]. Frontiers of Chemistry in China, 2006, 1(4): 465-468.
Xin Yan, Yu Ying, Zhang Yu, Fan Zhongyong. Crystallization behavior of single or pauci chain aggregates of isotactic polystyrene. Front. Chem. China, 2006, 1(4): 465-468.
