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Morphology and property of polyethylene pipe extruded at the low mandrel rotation
Author(s) -
Nie Min,
Wang Qi,
Bai ShiBing
Publication year - 2010
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.21700
Subject(s) - mandrel , materials science , extrusion , polyethylene , composite material , rotation (mathematics) , cylinder stress , ultimate tensile strength , stress (linguistics) , geometry , mathematics , linguistics , philosophy
Abstract During the rotation extrusion of polyethylene (PE) pipes, with the rotating mandrel, compressed air as a cooling medium was introduced through their interior to achieve the quick cooling of the inner wall. The experimental results showed that the hoop stress exerted by mandrel rotation could promote the molecular orientation in the hoop direction; moreover, the introduction of compressed air could quicken its inner wall's cooling rate so as to slow down the relaxation of the oriented molecule and to reserve the orientation structure. Therefore, the hoop orientation degree increased with the increasing inner wall's cooling rate. As a result, the performance of the PE pipe was greatly enhanced. The hoop tensile strength of the PE pipe produced by the novel extrusion method increased from original 24.1 MPa up to 35 MPa; the pipe's crack initiation time increased from 27 to 60 h and the crack growth rate slowed down. POLYM. ENG. SCI., 50:1743–1750, 2010. © 2010 Society of Plastics Engineers