STRUCTURE FORMATION AND CRYSTALLIZATION IN TWO-PHASE POLYMER BLEND FLOWS (FIBERS, POLYETHYLENE, POLYPROPYLENE) | Posted on:1987-04-08 | Degree:Ph.D | Type:Dissertation | University:University of Illinois at Urbana-Champaign | Candidate:SAKELLARIDES, STEFANOS L | Full Text:PDF | GTID:1471390017459502 | Subject:Engineering | Abstract/Summary: | | Flow induced crystallization of high density polyethylene and polypropylene has been studied in a two-phase flow system using linear low density polyethylene as the carrier phase. Extensional stresses were generated under slow flow conditions by either of two methods: one involving flow past a stationary seed, the other involving a droplet deformation and bursting mechanism. In both cases, oriented, fibrillar crystallization of the high density phase was observed optically and correlated with calculations indicating the presence of flow-induced extensional gradients. Morphological, thermal, and birefringence data indicate that the crystalline fibers produced are oriented and superheatable, and consist of a multifibrillar substructure. For fibers produced by the droplet bursting process a semi-quantitative agreement was found between fiber melting point and birefringence based on the simplified analysis for the bursting induced extensional flow. These results demonstrate that two-phase flows of crystallizable systems are a convenient means for studying the phenomenon of flow induced crystallization in polymer melts. | Keywords/Search Tags: | Flow, Crystallization, Two-phase, Polyethylene, Induced, Fibers | | Related items |
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