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Zhidk. krist. ikh prakt. ispol'z. = Liq. Cryst. and their Appl., 2014, 14 (3), 15—23.
Non-Newtonian Flow of Structured Systems. XII. Elasticity of Polymer Melts
E. A. Kirsanov, Yu. N. Timoshin
Author affiliations Moscow State Region Socio-Humanitarian Institute
Zelenaya st., 30, 140410 Kolomna, Moscow Region, Russia. E-mail: Kirsanov47@mail.ru
Abstract The structural rheological model for the description of the elastic properties of polymer melts under steady state flow is discussed. The new equation for the first normal stress difference N1 includes coefficients, connected with molecular elasticity and structural elasticity. This elasticity equation describes experimental dependence at high shear rates. The nonlinear dependence is explained by gradual destruction of the elastic macromolecular associates with increasing shear rate. The linear dependence was obtained at low shear rates. The cause of the linear dependence consists in the fact that the dimensions of the elastic macromolecular associates do not change in the range of low shear rates. The rheological behavior of low density polyethylene and polypropylene is described. The new model is an alternative to the well-known description of elasticity with the help-means of spring and damper mechanical models.
Keywords: viscoelastic systems, polymer melts, structural rheological model, first normal stress difference, equation of elasticity