Flow Induced Crystallization of Polyethylene Fibers From Solution
Rietveld, Jeroen
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https://hdl.handle.net/2142/69749
Description
Title
Flow Induced Crystallization of Polyethylene Fibers From Solution
Author(s)
Rietveld, Jeroen
Issue Date
1984
Department of Study
Chemical Engineering
Discipline
Chemical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Chemical
Abstract
This study deals mainly with investigating the growth sequence of a polyethylene fiber in the Poiseuille flow geometry. Features of an earlier study using the surface growth method to produce polyethylene fibers in Couette geometry are also included in the discussion. Fiber growth is initiated from a polyethylene seed inserted into a capillary tube and the growth phenomenon is observed through crossed polars. The formation of an unoriented, concentrated and amorphous phase is documented. This precursor fiber becomes crystalline through the growth of oriented crystallites and results in a gradual increase of fiber birefringence. The duration of the transformation sequence is effected by both flow rate and crystallization temperature, and decreases with the former whereas it increases with the latter. The role of trapped entanglements acting as semipermanent crosslinks is discussed and an analysis of the crystallization data is made based on the treatment given to crosslinked polymers under strain. The results obtained as such are in correct agreement with theory. Further studies are required to understand the exact nature of the precursor fiber and its formation.
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