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Rheological behavior of ultrahigh molecular weight polyethylene semidilute solutions. I. Solvent effect
Author(s) -
Zhang Anqiu,
Chen Kequan,
Zhao Hentai,
Wu Zongquan
Publication year - 1989
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1989.070380715
Subject(s) - decalin , solvent , rheology , thermodynamics , viscosity , theta solvent , shear rate , quantum entanglement , materials science , newtonian fluid , polymer chemistry , activation energy , chemistry , solvent effects , physics , organic chemistry , quantum mechanics , quantum , catalysis
The rheological behavior of ultrahigh molecular weight polyethylene (UHMWPE) semidilute solutions with different solvents has been studied. In a temperature range of 150–185°C, the viscosity of a UHMWPE semidilute solution with paraffin oil as solvent (soln 1) is more temperature‐independent and viscosity‐stable than that with decalin as solvent (soln 2). Usually the reduction of the molecular entanglement density in solution causes a rapid reduction in viscosity. Apparently soln 1 has a different entanglement density compared with soln 2. The activation energy of UHMWPE semidilute solutions changes with both shear stress and shear rate. The regressive equations for both solutions in between E σ and σ or E ṙ and \documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma } $\end{document} have been obtained from a least‐squares method. Finally, there is a discontinuity in the non‐Newtonian flow region of η vs. \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} curve, no matter which temperature or solvent was used. The discontinuity occurs at a shear rate of about 70 s −1 , where a transformation from a qualitative change in entanglement in the solution takes place.