ON THE EFFECT OF PRESSURE ON THE SHEAR AND ELONGATIONAL VISCOSITIES OF POLYMER MELTS
Tomas Sedlacek, Martin Zatloukal, Anezka Lengalova, Petr Saha
Tomas Bata University in Zlin
Czech Republic

Keywords: viscosity-pressure dependence, White-Metzner model, pressure coefficient

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The pressure dependencies of shear and elongational viscosities of selected polymer melts were measured on a capillary rheometer modified by an addition of a second chamber below the main capillary. The chamber equipped with a constraining needle enables the change in pressure in the range of 10 to 70 MPa. The obtained viscosity values were the input in the modified White-Metzner model serving for the calculation of coefficient b, expressing the dependence of the melt viscosity on pressure. The results reveal that the pressure of the melt can significantly affect both shear and extensional viscosities.