Determination of thermal conductivity of liquids and polymers from batch mixer data

Abstract

The paper proposes a new technique allowing the determination of thermal conductivity of liquids and polymer melts with unknown rheological behavior from batch mixer data; the mixing elements can have simple or complex geometries. The simple mixer is represented by an equivalent simple Couette with a cup and a bob having an effective hydrodynamic (or thermal) radius, and the true batch mixer is represented by two adjacent concentric cylinder viscometer. Using the universal internal effective radius, the thermal conductivity for four polymers was estimated from the batch mixer temperature–rotor speed and torque data. A good agreement was found with the values measured by transient line source method and those of the literature. Melt activation energy was calculated from torque–temperature batch mixer data, and the obtained values were found to be consistent with the values extracted from low-amplitude oscillatory shear experiments as well as with the available published data.