Román Marín, José Manuel6; Huusom, Jakob Kjøbsted1; Javier Alvarez, Nicolas1; Huang, Qian1; Rasmussen, Henrik K.4; Bach, Anders7; Skov, Anne Ladegaard8; Hassager, Ole1
1 Department of Chemical and Biochemical Engineering, Technical University of Denmark2 The Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark3 Computer Aided Process Engineering Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark4 Department of Mechanical Engineering, Technical University of Denmark5 Manufacturing Engineering, Department of Mechanical Engineering, Technical University of Denmark6 Risø National Laboratory for Sustainable Energy, Technical University of Denmark7 Coloplast Danmark A/S8 Centre for oil and gas – DTU, Center, Technical University of Denmark
We propose a new control scheme to maintain a constant strain rate of the mid-filament diameter in a filament stretching rheometer for polymer melts. The scheme is cast as a velocity algorithm and consists of a feed-back and a feed-forward contribution. The performance of the controller is demonstrated on a commercial low density polyethylene. Several strain rates and experimental conditions are tested to demonstrate the necessity of the control parameters and the limits of both the control scheme and the experimental apparatus. When the control parameters are properly tuned, the algorithm ensures that the applied strain stays within 2% of the set point and measurements can be made up to Hencky strains of 6.5.
Journal of Non-newtonian Fluid Mechanics, 2013, Vol 194, p. 14-22