LDPE及LDPE/TiO_2纳米复合材料的熔限及等温结晶研究

Research of Melting Temperature,Melting Range and Isothermal Crystallization of LDPE and LDPE/TiO_2 Nanocomposites Determined by Dilatometry

采用熔融共混法制备了LDPE/TiO_2纳米复合材料,以膨胀计对LDPE及LDPE/TiO_2复合材料的熔点、熔限及等温结晶进行了研究。结果表明:膨胀计可用于LDPE及LDPE/TiO_2纳米复合材料熔点及熔限的测试;与LDPE相比,LDPE/TiO_2复合体系的半结晶期及Avrami指数较小,表明TiO_2粒子对LDPE的结晶具有明显的异相成核作用;而Avrami指数为非整数,且Avrami作图直线的最后部分与实验点的偏离,则表明LDPE及LDPE/TiO_2纳米复合材料的等温结晶过程比Avrami方程要复杂得多。

The LDPE/TiO2 nanocomposites were prepared by melt-compounding, the melting temperature, melting range and the isothermal crystallization kinetics were characterized by dilatomery. The experimental results showed that the dilatometry can be used to test the melting temperature, melting range of LDPE and LDPE/TiO2 nanocomposites easily; the relatively lower half crystallization time （t1/2） and Avrami index indicated that the TiO2 nanoparticles in the composites matrix showed obvious heterogeneous nucleation effect on the crystallization of LDPE. Avrami index was not integer, and the later part of the beeline of the Avrami equation deviated from the experimental data, indicating the isothermal crystallization of LDPE and LDPE/TiO2 nanocomposites was more complex than that described by Avrami equation.