取代芳基杂环磷酸盐类成核剂改性等规聚丙烯的非等温结晶动力学

采用示差扫描量热(DSC)法对取代芳基杂环磷酸盐类成核剂(简称成核剂)改性等规聚丙烯(iPP)的非等温结晶动力学进行了研究,采用Caze法对DSC数据进行了处理。实验结果表明,一价成核剂的加入可大幅度提高iPP的结晶峰温度并缩短半结晶时间,当冷却速率为10℃/min时,iPP-2,2′-亚甲基双(4,6-二叔丁基苯基)磷酸钠的结晶峰温度可从iPP的117.6℃提高到131.2℃,半结晶时间可从44s缩短到26s;而二价和三价成核剂对iPP的结晶峰温度和半结晶时间的影响相对较小。成核剂的加入改变了iPP的晶体生长方式,对于iPP,Avrami指数为3.71,表明iPP为均相成核的三维球晶生长方式;而对于成核iPP,Avrami指数基本都接近于3,表明成核iPP为异相成核的三维球晶生长方式。不同成核剂的加入都可提高iPP的结晶活化能。

Non-Isothermal Crystallization Kinetics of Isotactic Polypropylene Modified by Substituted Aromatic Heterocyclic Phosphates as Nucleating Agent

Non-isothermal crystallization kinetics of isotactic polypropylene(iPP)modified by substituted aromatic heterocyclic phosphates as nucleating agent was studied by means of differential scanning calorimetry(DSC).Caze method was used to deal with DSC results.Addition of monovalent metallic salts of substituted aromatic heterocyclic phosphate can greatly raise crystallization peak temperature of iPP and shorten its crystallization half-time,but bivalent and trivalent metallic salts have only small effects.Addition of nucleating agents can change mode of iPP crystal growth.Avrami exponent of iPP is 3.71,indicating homogeneous nucleation with three-dimensional spherulite growth of iPP exists.Avrami exponents of nucleated iPP are close to 3,indicating heterogeneous nucleation with three-dimensional spherulite growth of nucleated iPP exists.Addition of various nucleating agents all raises crystallization activation energy of iPP.