α/β复合成核剂协同增强煤基均聚聚丙烯力学性能

Synergistic Improving of Mechanical Properties of Coal-Based Homo Polypropylene by a/β Hybrid Nucleating Agent

针对煤基均聚聚丙烯(PP)结晶过程中β晶型成核生长能力较弱、冲击强度较低的问题,利用差示扫描量热仪(DSC)、广角X射线衍射仪(WAXD)和万能材料实验机研究了单独添加a,β和复合添加a/β成核剂对煤基均聚聚丙烯的结晶性能和力学性能的影响。研究表明,单独添加a或β成核剂均会存在一定的性能缺陷。DSC结果表明,a/β复合成核剂中β成核剂的存在会抑制a晶型的生成,β晶熔融峰强度会增加,在降温结晶曲线中也呈现出明显的β晶优先成核现象。WAXD结果表明,复合成核剂可以提高聚丙烯的β晶体的相对含量(K_(β))。a/β复合成核剂的加入有助于同时实现煤基均聚聚丙烯的刚韧平衡,当复合成核剂质量分数为0.15%、a/β比例为1:2时,PP的拉伸强度、断裂伸长率和冲击强度分别提高了15.9%,305.3%和72.5%。

In order to solve the problems of weak β nucleation and crystal growth in the crystallization process of coal-based homo polypropylene(PP) and its resultant low impact strength, the effects of adding a or β nucleating agent and a/β hybrid nucleating agent on the crystallization and mechanical properties of coal-based homo PP were studied by differential scanning calorimetry(DSC), wide angle X-ray diffraction(WAXD) and universal material tester. The results show that adding a or β nucleating agents will lead to certain performance defects. DSC results show that the presence of β nucleating agent in a/β hybrid nucleating agent will inhibit the generation of a crystal type, the intensity of β crystal melt peak will increase, and the preferential nucleation of β crystal is also obvious in the cooling crystallization curves. Meanwhile, XRD results show that the hybrid nucleating agent could increase the relative content of β-crystal(K_(β)) of coal-based homo polypropylene. The addition of a/β hybrid nucleating agent helps to achieve the stiffness and toughness balance of coal-based homo polypropylene. When the hybrid nucleation agent mass fraction is 0.15%(a/β ratio is 1:2), the tensile strength, elongation at break and impact strength of coalbased homo PP are increased by 15.9 %, 305.3 % and 72.5 %, respectively.