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 (t 1/2) 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.
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Translated from Chemical Journal of Chinese Universities, 2005, 26(10) (in Chinese)
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Xin, Y., Yu, Y., Zhang, Y. et al. Crystallization behavior of single or pauci chain aggregates of isotactic polystyrene. Front. Chem. China 1, 465–468 (2006). https://doi.org/10.1007/s11458-006-0044-7
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DOI: https://doi.org/10.1007/s11458-006-0044-7