Extension induced phase separation and crystallization in semidilute solutions of ultra high molecular weight polyethylene

POLYMER

卷:136

Article

Wingstrand, Sara Lindeblad¹  Imperiali, Luna²  Stepanyan, Roman²  Hassager, Ole¹ 

[1] Tech Univ Denmark, Dept Chem & Biochemcial Engn, Danish Polymer Ctr, DK-2800 Lyngby, Denmark

[2] DSM Res Performance Mat, Mat Sci Ctr, NL-6160 BB Geleen, Netherlands

关键词: Crystallization;    Extensional flow;    Rheology;   

DOI  :  10.1016/j.polymer.2017.12.042

来源: Elsevier

【 摘 要 】

We investigate the influence of controlled uniaxial extension on various flow induced phenomena in semidilute solutions of ultra high molecular weight polyethylene. Concentrations range from 9 w% to 29 w% and the choice of solvent is paraffin oil. The start-up extensional behavior is measured at various Hencky strain rates epsilon and at two different temperatures (150 degrees C and 170 degrees C) well above the melting point. For Hencky strains epsilon > 0.9 the qualitative behavior of the samples differ significantly depending on the imposed conditions and the concentration of the samples. Overall we propose two flow scenarios: Scenario 1 - flow induced phase separation resulting in an unstable bulky filament and Scenario 2 - flow induced phase separation and crystallization resulting in a stable deformation and a smooth strongly strain hardening filament. Scenario 2 is observed only at 150 degrees C at high epsilon and high concentrations. Scenario 1, observed at both temperatures, is most pronounced at low rates and/or high concentrations. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

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