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Zhidk. krist. ikh prakt. ispol'z. = Liq. Cryst. and their Appl., 2018, 18 (1), 55—65. DOI: 10.18083/LCAppl.2018.1.55
Non-Newtonian Flow of Structured Systems. XXV. Viscoelasticity of Polymer Melts
E. A. Kirsanov, Yu. N. Timoshin
Author affiliations State University of Humanities and Social Studies,
30 Zelyonaya St., Kolomna, 140411, Moscow Region, Russia E-mail: Kirsanov47@mail.ru
Abstract Structural rheological model is used to interpret the results of dynamic measurements of polymer melts, namely, low density polyethylene, high density polyethylene, polystyrene, fluoropolymer, copolymer of propylene-ethylene, linear low density polyethylene. The rheological curves G''(ω) and G'(ω) of all these polymers have similar character. In the interval of high frequencies of shear oscillations, the curves can be approximated by the equations of structural rheological model, which describes the change in the viscoelastic properties while changing the structure of matter under the action of shear vibrations. In the interval of low frequency, the structure of polymer samples does not change or changes a little. In this case, the loss modules and the storage modules are described by a linear dependence. The straight lines G'(ω) intersect the axis below the origin of coordinates. The straight lines G''(ω) intersect the axis above the origin or at the origin of coordinates. The quadratic dependence G' ∼ ω2 is rarely observed at the very low frequencies.
Keywords: polymer melts, viscoelastic properties, structural rheological model