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Swelling behavior in extrusion
Author(s) -
Miller John C.
Publication year - 1963
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760030208
Subject(s) - die swell , swelling , materials science , extrusion , composite material , body orifice , die (integrated circuit) , capillary action , thermoplastic , viscoelasticity , mechanical engineering , engineering , nanotechnology
The diameter increase of a molten thermoplastic extrudate is discussed in terms of the viscoelasticity of the resin. A swelling index, the ratio of the extrudate diameter to the orifice diameter, is defined. It was observed that swelling data taken at different temperatures can be correlated with stress in the die. An unexpected influence on the swelling for polyethylenes is the length of the die where short dies show larger swelling than long dies. Some suggestions for reducing swelling tendencies are made based on a simple model for flow in a capillary.