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Abstract

The flow behavior of several low molecular weight polymers has been studied as a function of shear rate and temperature. These polymers, which had terminating hydroxyl or bromine groups, included homopolymers of polybutadiene and acrylonitrile–butadiene and styrene–butadiene copolymers. Viscosity was measured as a function of shear rate for the temperature range 25°–35°C, and the limiting zero shear viscosities were obtained for the range 25°–60°C. A cone plate viscometer was employed to measure the effect of shear rate on viscosity, and a Brookfield viscometer was used to verify the zero-shear rate values. A tendency of the fluid to flow out of the cone-plate gap was observed for some of the materials studied. From the viscosity data, characteristic times were estimated, and the data were compared with two constitutive equations. A modified Arrhenius equation was fitted to the zero-shear viscosity data. In the case of one material, it was possible to test the Nakajima relationship between viscosity and molecular weight distribution. The dependence of material parameters on temperature is discussed in detail.