Isothermal crystallization kinetics of poly(phenylene sulfide)/TLCP composites
Isothermal crystallization kinetics of poly(phenylene sulfide)/TLCP composites
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DOI：
10.1002/pen.21263
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发表时间：
2009-02
影响因子：
3.2
通讯作者：
A. K. Kalkar;V. Deshpande;M. J. Kulkarni
中科院分区：
文献类型：
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作者：
A. K. Kalkar;V. Deshpande;M. J. Kulkarni
采用差示扫描量热法（DSC）和光学显微镜研究了聚苯硫醚（PPS）与热致液晶共聚酯Vectra A950 （TLCP）的熔融复合材料的等温结晶动力学、形貌和熔融行为。PPS/TLCP复合材料中PPS的结晶行为对复合材料中Tc和不混相TLCP的含量高度敏感。TLCP的存在显著降低了PPS/TLCP复合材料中PPS的球晶生长速率、总结晶速率和活化能。Avrami动力学参数（n和k）分析表明，TLCP与PPS共混导致了非均相生长过程和成核机制。在低Tcs条件下，PPS的结晶速率比TLCP负载≤30 wt%的纯PPS快，而在高Tcs条件下，PPS的结晶速率几乎保持不变。对复合材料熔炼行为的分析表明，聚硫磷晶体的稳定性和结构重组都受到复合材料成分和Tcs的影响。随着复合材料中TLCP含量的增加，球晶的大小和数量随复合材料成分的变化有较大的变化，在一定的Tc下，球晶的生长速度下降较快。基于Lauritzen-Hoffmann二次成核理论的分析，利用现有的DSC数据表明，在现有的Tcs范围内，现有的数据主要遵循线性增长趋势，复合材料中的PPS结晶仍然按照状态II动力学发生，即在衬底上形成多个表面核，在初始形成的生长层完成之前就开始了多个成核行为。复合材料中PPS链的折叠面自由能高于整齐PPS链的折叠面自由能，导致链折叠功平均更高，这归因于复合材料熔体中PPS链迁移率的普遍发展。变异较大。ENG。科学。, 2009年。©2008塑料工程师协会
The isothermal crystallization kinetics, the morphology, and the melting behavior of melt-processed composites of poly(phenylene sulfide) (PPS) with a thermotropic liquid crystalline copolyester, Vectra A950, (TLCP) were studied by differential scanning calorimetry (DSC) and optical microscopy. The crystallization behavior of PPS in PPS/TLCP composites is observed to be highly sensitive to Tc and immiscible TLCP content in the composites. The spherulite growth rate, the overall crystallization rate, and the activation energy of PPS in PPS/TLCP composites are markedly depressed by the presence of TLCP. The analysis of the Avrami kinetic parameters (n and k) indicates that blending of TLCP with PPS causes heterogeneous growth process and nucleation mechanisms. At low Tcs, the PPS crystallization rate is faster than that neat PPS with ≤30 wt% TLCP loading whereas at high Tcs it remains almost unchanged. The analysis of the melting behavior of these composites indicates that the stability of PPS crystals and their reorganization is influenced both by the Tcs and the composite compositions. The sizes and the number of spherulites change a great extent with composite composition with a drop of spherulite rapid growth rate, at constant Tc, with increasing content of TLCP in composites. The analysis based on the Lauritzen-Hoffmann secondary nucleation theory, using present DSC data, indicates that present data predominantly follow a linear growth trend over a present range of Tcs and PPS crystallization in composites still occurs according to regime II kinetics, whereby multiple surface nuclei form on the substrate with multiple nucleation acts commencing before initially formed growth layer is completed. The fold surface free energy of PPS chains in composites is found higher than that of neat PPS, leading to an average higher work of chain folding and is ascribed to a general development of the PPS chain mobility in the composite melt. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers