拉丝级聚丙烯断裂伸长率不合格原因分析

Analysis of Reason for Unqualified Elongation at Break of Drawn Grade Polypropylene

针对拉丝级聚丙烯产品PPH-T03断裂伸长率骤降、异常断裂的现象,通过高温凝胶渗透色谱仪、正庚烷萃取法、差示扫描量热仪等研究了产品的相对分子质量分布、等规度和结晶性能,分析了产品断裂伸长率降低的原因。结果表明:合格产品与不合格产品分子链结构的差异很小。不合格产品所用添加剂中可能含有杂质,使其结晶温度偏高、熔点偏高、结晶度偏大,且球晶细碎,导致其断裂伸长率骤降。更换添加剂批次后,产品的断裂伸长率符合要求,产品合格。

Aiming at the phenomenon of sudden drop in elongation at break and abnormal breaking of PPH-T03,a drawing grade polypropylene product,the relative molecular weight distribution,isotacticity and crystallization property of product were studied by high temperature gel permeation chromatography,n-heptane extraction method,differential scanning calorimetry,etc.The reasons for the drop in elongation at break of product were analyzed.The results show that there is little difference in the molecular chain structure between qualified product and unqualified product.The additives used in unqualified product may contain impurities,resulting in high crystallization temperature,high melting point,high crystallinity and fine spherulites,leading to a sudden decrease in elongation at break.After replacing the batch of additives,the elongation at break of product meets the requirements and the product is qualified.