Dispersion, temperature and torque models for an internal mixer

Abstract

Models based on kinetic, thermodynamic and rheological equations have been developed to compute dispersion extent, batch temperature and relative batch viscosity at discrete intervals during a mix cycle in an internal mixer. The calculated relative bulk viscosity can be linked empirically to a measured variable such as rotor torque or power consumption. Solution of the models over successive time intervals allows the computation of complete dispersion, temperature, and torque/power profiles for a mix cycle. The mix models exhibit good fits to experimental torque and temperature curves for mixing natural rubber with carbon black over a wide range of carbon black loadings (0 to 50 phr) for rotor speeds ranging from 40 to 70 RPM in two lab‐scale internal mixers. The models are shown to be suitable for moderately reinforcing (ASTM N660) as well as highly reinforcing (ASTM N121) grades of carbon black. Rate constants for filler dispersion, incorporation and erosion can be extracted from the models and can be interpolated to generate dispersion, temperature and torque curves at new conditions of carbon black loading and rotor speed. The mix models could thus be used for process‐control purposes and for specifying drop targets based on batch properties in addition to the time‐temperature‐energy criteria typically used today. Polym. Eng. Sci. 44:1247–1257, 2004. © 2004 Society of Plastics Engineers.

Processing of wood plastic composites: The influence of feeding method and polymer melt flow rate on particle degradation

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Nonisothermal modeling of heat transfer inside an internal batch mixer

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