Temperature measurement in single screw extrusion: late melting and thermal instabilities
Elaine Brown, Adrian Kelly, Phil Coates
University of Bradford
UK

Keywords: Extrusion, Temperature, Melting

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Various temperature measurement techniques have been used to investigate thermal profiles in the die of a 60mm single screw extruder, including invasive and wall mounted thermocouples, thermocouple meshes, ultrasound, and infrared. For a general-purpose polyolefin screw, large temperature differences of the order of 20°C were observed over short time periods of the order of 1 second, in the exit melt temperature. These instabilities were not detected by thermocouples or pressure sensors at the wall, but were evident during measurement of bulk melt temperature. Predictive temperature plots obtained from CFD simulations using a commercial software package are compared to empirical results.