Torque viscometry of molten polymers and composites

A systematic approach for collecting data from a torque rheometer is described, and the Bousmina et al. model is evaluated for HDPE, LDPE, LLDPE and HDPE/filler composites. The torque rheometer results are in good agreement to capillary and parallel plate viscometer measurements for neat polymers, when the torque values measured are corrected for the temperature rise due to viscous dissipation. For the composites, the torque and capillary results virtually coincide, but the viscosities are lower than those measured with the parallel plate instrument, in oscillatory mode, because the Cox-Merz rule is not valid. Although there are some limitations at high shear rates, due to viscous dissipation, the present work provides a proof and a methodology for the practical utility of torque rheometers for viscosity measurement in highly viscous systems. © Appl. Rheol.