Experimental Study of the Flow of Highly Viscous Materials

An experimental apparatus was designed and fabricated to study the flow of highly viscous synthetic rubber material. The flow rate, pressure drop, and temperature rise of the material was monitored during flow through the test section. Viscous heating was found to generate a significant temperature rise. Density, thermal conductivity, heat capacity, and apparent viscosity measurements were made for the test material at various temperatures. The dependence of viscosity upon shear rate was also measured. At temperatures above 250° F, the material starts vulcanizing and the Mooney viscosity increases rapidly. This was also observed for flow in capillary tubes at elevated temperatures where dramatic pressure increases reflect curing of material during flow. The property measure ments are used to predict the flow curve with a mathematical model that considers temperature-dependent viscosity. Agreement with the experimentally determined flow curve is excellent.