Abstract
Speciality engineering thermoplastics are steadily gaining importance in a wide variety of high temperature applications due to their excellent performance char acteristics at elevated temperatures. A knowledge of the rheological behaviour of these speciality polymers over an industrially relevant range of shear rate and temperature is essential m the design of polymer processing equipment, process optimization and trouble-shooting. A method proposed earlier has been extended to estimate the complete flow curves for some of the important speciality poly mers such as polyphenylene oxide, polyphenylene sulfide, polyether sulfone, polyaryl sulfone, polyether ether ketone, polyetherimide and polyarylates, through the use of the developed grade- and temperature-independent unified curves along with the appropriate melt flow index value. The master curves have been fitted by appropriate rheological models and then using a single integral constitutive equation of the BKZ type the unified normal stress difference curves have been predicted. These unified normal stress difference curves would be useful for determining the elastic flow parameters for the speciality polymer melts merely from the knowledge of the melt flow index.
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