Azadeh Farahanchi, Dynisco Rheological Scientist, Ph.D. Kevin Craig, Dynisco Online Rheology Engineering Manager Dynisco, 38 Forge Parkway, Franklin, MA 02038 ABSTRACT The growing tendency towards productivity, efficiency, and sustainability among manufactures and recyclers in the plastics industry arises the necessity of timely control of the process and quality while eliminating the waste amount. Online rheometers have increasingly been used in variety of extrusion lines to have continuous data stream of rheological properties and real-time information on the process without any delay for the laboratory testing. A newly designed online rheometer, Dynisco’s ViscoIndicator (VI), has been developed to duplicate the test conditions of laboratory rheometers, continuously provide information on the melt flow rate (MFR), and shear viscosity of in-process extrudate materials. The present work aims to describe how this online rheometer has been designed on an extruder to closely match results from a melt flow rate tester or capillary rheometer. Moreover, through calculation of activation energy for a specific material and introducing a temperature correlation, it has been investigated how the ViscoIndicator Online Rheometer considers the temperature dependency of material`s rheological properties and accurately measures these parameters at various operating temperatures.