等规聚丙烯与液晶成核剂的共混改性研究

以单丙烯酸酯液晶单体（RLC）为成核剂，通过共混反应法对等规聚丙烯（iPP）进行改性，制备含β晶型的聚丙烯产品（β-iPP）。首先介绍了β-iPP的制备工艺，然后通过偏光显微镜、广角X射线衍射对纯iPP、iPP/RLC共混物的球晶结构进行了分析；最后通过X射线衍射、差示扫描量热分析等测试方法研究共混物的结晶结构、结晶行为和热性能。结果表明，液晶成核剂RLC能够诱导iPP生成β晶型；制备β-iPP的最佳工艺条件是RLC含量为0.5 %（质量分数，下同），结晶温度为110 ℃；β晶型相比于α晶型处于热力学亚稳态，在升温过程中，会发生β晶向α晶的转变，但较高的升温速率会抑制这一转变。

Blending Modification of Isotactic Polypropylene and Liquid Crystal Nucleating Agents

β-form containing polypropylene was prepared using a liquid crystal monoacrylate monomer (RLC) as a nucleating agent. Polarized light microscope was adopted to study the nucleation process, crystallization behavior, and spherulites morphology of the polypropylene. The crystal structure was also investigated by X-ray diffraction and differential scanning calorimeter (DSC). When the mass fraction of RLC was 0.5 wt % and the crystallization temperature was 110 ℃. Compared with α-form, β-form was thermodynamically metastable and could be affected by the temperature fluctuation. The metalstable β-form could transform into α crystal form, while a higher heating rate would inhibit this transformation.