Abstract
The measurement of elongational viscosity of polybutene-1 melt has been carried out at a constant strain rate with an elongational rheometer which measures simultaneously the diameter of elongating samples. Non-linearity parameter of the viscosity was calculated from the total elongational viscosity values by dividing with the values of linear parts. The non-linearity parameters of the elongational viscosity were almost independent of strain rate and temperature. Four rheological constitutive models of integral type were chosen and applied for the elongational flow at a constant strain rate. The chosen models were the Lodge model, the Bogue and White model, the Bernstein, Kearsley and Zapas model, and the Wagner model. These models predicted the non-linearity of the elongational viscosity at high strain rate well. However, the non-linearity parameter predicted from these constitutive models showed strong dependences on both strain rate and temperature.
