Making Better use of the Melt Flow Rate Instrument - Multi-rate and Extensional Flow Measurements

摘要

The melt flow rate method is widely used in quality control within the polymer industry and is likely to remain as a dominant tool for quality control and assurance. However, it is widely accepted within the industry that the melt flow rate method has limitations. To address these limitations various developments to the melt flow rate method have been undertaken and are reported here. These developments encompass: the use of multi-load testing to enable melt flow rate data to be extrapolated more reliably to higher shear rate, the use of alternative die geometries to separate the shear and extensional flow behaviours and the measurement of extrudate swell. The results presented demonstrate good agreement of shear viscosity and entrance pressure drop data measured using the multi-rate melt flow rate method with data obtained using a capillary extrusion rheometer.