The Collin ® on-line rheometer determines the viscosity function of a polymer melt over a wide range of shear rates. To reduce the effort involved in performing the measurement, the melt flows through three capillaries simultaneously. This is accomplished by having a three-outlet gear pump divide the melt coming from the extruder into three identical flows for each capillary. Absolutely precise temperature control in the extruder and along all subsequent flow paths guarantees an exact temperature. User-friendly software determines the viscosity function of the melt from the pressure drop in each capillary. In addition, the Carreau coefficients, Bagley correction and WLF temperature shift are also determined by the evaluation program. In this way, it is possible to establish the viscosity function that is so important when designing the flow characteristics of molds, dies and screws with a minimum of time and effort.
