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首页> 外文期刊>Journal of Applied Polymer Science >Polylactide/Nano- and Micro-Scale Silica Composite Films. II. Melting Behavior and Cold Crystallization
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Polylactide/Nano- and Micro-Scale Silica Composite Films. II. Melting Behavior and Cold Crystallization

机译：聚乳酸/纳米和微米级二氧化硅复合薄膜。二。熔融行为和冷结晶

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摘要

Nonisothermal crystallization of polylactide (PLA)/silica composites prepared by (i) directly blending the PLA with nanoscale colloidal silica sol and by (ii) a sol– gel process are studied by differential scanning calorimeter (DSC) at various heating rates. Samples quenched from the molten state exhibited two melting endotherms(T_(ml) and T~(mh))due to melt-recrystallization during the DSC scans. Lower heating rate and the presence of silica particles generate a lower peak intensity ratio of T_(ml) /T_(mh).The nonisothermal crystallization kinetics is analyzed by modified Avrami model, Ozawa model, and Liu-Mo models. The modified Avrami and Liu-Mo models successfully described the nonisothermal cold crystallization processes, but Ozawa is inapplicable. The nucleation constant (K_g) is calculated by modified Lauritzen-Hoffman equation and the activation energy by Augis-Bennett, Kissinger, and Takhor models. These calculated parameters indicate consistently that the nanoscale silica particles seem to form more heterogeneous nucleation to increase crystallization, but microscale one form hindrance to retard crystallization.
机译：通过差示扫描量热仪（DSC）在不同的加热速率下研究了（i）直接将PLA与纳米级胶体二氧化硅溶胶共混，以及（ii）溶胶-凝胶法制备的聚乳酸（PLA）/二氧化硅复合材料的非等温结晶。在DSC扫描过程中，由于熔融重结晶，从熔融态淬灭的样品表现出两个熔融吸热峰（T_（ml）和T〜（mh））。较低的加热速率和二氧化硅颗粒的存在会产生较低的峰强度比T_（ml）/ T_（mh）。通过改进的Avrami模型，Ozawa模型和Liu-Mo模型分析了非等温结晶动力学。修改后的Avrami和Liu-Mo模型成功地描述了非等温冷结晶过程，但Ozawa不适用。成核常数（K_g）由修正的Lauritzen-Hoffman方程计算，活化能由Augis-Bennett，Kissinger和Takhor模型计算。这些计算出的参数一致地表明，纳米级二氧化硅颗粒似乎形成了更多种的异相形核，以增加结晶度，而微米级二氧化硅形式则阻碍了结晶化。

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