Nucleation and growth mechanism of polymers with high purity-important role of molecular weight

根据分子量(M)与成核和生长速率的关系的最新实验结果，对高纯聚合物的成核和生长机理进行了研究。在常压和高压(P=4kb)条件下，对纯的、分级较好的聚乙烯(PB)和等规聚丙烯(IPP)进行了等温结晶。在PE上发现，Vocm^-^H是一个常数，被称为“横向生长速率的幂定律”。在IPP上也发现了类似的规律，并首次在PE上发现了IOCM^-^H，命名为“成核速率的幂定律”。这些结果表明，结晶机理中的“幂定律”具有普遍性。提出了一个拓扑模型，解释了聚合物的成核和生长过程是一个在熔体、晶核、晶体以及熔体与晶界之间解缠和链滑动扩散的过程。

Nucleation and growth mechanism of polymers with high purity was studied based on the new experimental findings on the molecular weight (M) dependence of nucleation and growth rates, 1 and V.respectively. Pure and well fractionated Polyethylene (PB) and isotactic polypropylene (iPP) were isothermally crystallized at atmospheric pressure or under high pressure (P=4kb). It is found on PE that V ocM^-^H, where His a constant, which was named "power law of lateral growth rate". Similar law was also found on iPP.It is also found on PE for the first time that I ocM^-^H which was named "power law of nucleation rate". These results suggest the universality of the "power law" in crystallization mechanism. A topological model was proposed to explain the results that the nucleation and growth of polymers is a process of disentanglement and chain sliding diffusion within the melt, nucleus, crystal and interface between the melt and crystals.