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Sakellarides, Stefanos L. 2014-12-15T19:54:32Z 2014-12-15T19:54:32Z 10000-01-01 1986 1986 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. Made available in DSpace on 2014-12-15T19:54:32Z (GMT). No. of bitstreams: 1 8701605.pdf: 6140485 bytes, checksum: 81ff18598e30dcfd8ea347d7b4b6b364 (MD5) Previous issue date: 1986 Embargo set by: Seth Robbins for item 69938 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 269 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986. http://hdl.handle.net/2142/69772 (UMI)AAI8701605 Engineering, Chemical Structure Formation and Crystallization in Two-Phase Polymer Blend Flows (Fibers, Polyethylene, Polypropylene) text Chemical Engineering Chemical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.