The effects of three different fillers (i.e., talc, calcium carbonate, and cassava starch) and surface functionalization by 3-aminopropyltriethoxysilane (APTES) and vinyltriethoxysilane (VTES) on morphology, thermal and tensile properties of the poly(lactic acid) (PLA) composites were comparatively examined. Dynamic differential scanning calorimetry (DSC) results revealed that the incorporation of filler can facilitate the cold crystallization of PLA, as confirmed by lowered cold crystallization temperature. By fitting DSC data with Avrami model, the highest isothermal cold crystallization rate constant k and the shortest crystallization half time t_1/2 were obtained for the PLA/talc composites under isothermal temperature of 100 °C, implying that talc was the most effective nucleating agent for PLA in this study. The average Avrami index n of neat PLA and its composites lay within the same range of 3.0–3.6, which reflected the three-dimensional spherulitic growth of PLA with the mixture of instantaneous nuclei and sporadic nuclei. In comparison with the composite cast films, the thermoformed films had higher degree of crystallinity as well as higher tensile strength and Young’s modulus owing to the chain orientation upon annealing. Furthermore, the addition of silane-treated talc, especially APTES-treated talc, fastened cold crystallization rate and enhanced tensile properties because of the improved interfacial interaction between talc particles and PLA matrix.

中文翻译：

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热成型聚乳酸复合材料的等温冷结晶动力学和性质：滑石，碳酸钙，木薯淀粉和硅烷偶联剂的作用

三种不同填料（即滑石粉，碳酸钙和木薯淀粉）和3-氨基丙基三乙氧基硅烷（APTES）和乙烯基三乙氧基硅烷（VTES）的表面官能化对聚乳酸（PLA）的形态，热和拉伸性能的影响复合材料进行了比较检查。动态差示扫描量热法（DSC）结果表明，填料的掺入可以促进PLA的冷结晶，这可以通过降低冷结晶温度来确认。通过用Avrami模型拟合DSC数据，可获得最高等温冷结晶速率常数k和最短结晶半衰期t _1/2在100°C的等温温度下获得的PLA /滑石复合材料的滑石粉，这表明滑石是PLA中最有效的成核剂。平均Avrami指数n纯PLA及其复合材料的最大射程在3.0-3.6的范围内，这反映了瞬时核和零散核的混合物对PLA的三维球状生长。与复合流延膜相比，由于退火时的链取向，热成型膜具有更高的结晶度以及更高的拉伸强度和杨氏模量。此外，由于改善了滑石颗粒与PLA基质之间的界面相互作用，添加了硅烷处理的滑石，特别是APTES处理的滑石，可加快冷结晶速率并提高拉伸性能。