Extensional flow induced crystallization from solution

摘要: An experimental apparatus and technique were developed for studying the crystallization of polyethylene from solutions undergoing an oscillatory, constant stretch rate, extensional flow. Investigation resulting fiber morphology, obtained at various temperatures rates, shows that fibers exhibit a bead stringlike appearance. Study melting, acid etching, selective dissolution behavior leads to conclusion growth occurs in fashion which directly results string morphology is not result secondary, epitaxial crystal as previously believed. A model process, suggested by data, presented. Evidence also presented suggest certain triclinic phase transformation during flow process. The effect produce two separate melting entities appear be rate sensitive, line with published studies on effects stretching bulk polymer.