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Effect of crystallization on drawdown force at capillary extrusion for polyethylene

By Jiraporn Seemork, Tomoki Itoh, Shogo Nobukawa and Masayuki Yamaguchi

Abstract

The effect of crystallization on the drawdown force, i.e., the force needed to stretch a molten polymer uniaxially, was studied using conventional polyethylene samples. It was found that the drawdown force of high-density polyethylene (HDPE) increases with increasing the die length. This is attributed to the rapid crystallization owing to the low density of entanglement couplings after passing through a long die. On the contrary, the die length has no/little influence on the drawdown force of linear low-density polyethylene (LLDPE), indicating that the molecular orientation applied in a long die is almost relaxed prior to the crystallization. Even for LLDPE, however, the drawdown force becomes sensitive to the die length by the addition of a small amount of HDPE, because the crystallization process is accelerated

Topics: Elongational Flow, Drawdown force, Polyethylene, Capillary extrusion, Crystallization
Publisher: 'Society of Rheology Japan'
Year: 2016
DOI identifier: 10.1678/rheology.44.23
OAI identifier: oai:dspace.jaist.ac.jp:10119/13786
Provided by: JAIST Repository

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