GOALI: Optimum Design of Extrusion Dies using the Estimated Elongational Viscosity of Polymers

Michigan Technological University, Houghton MI

Investigators

Abstract

This Grant Opportunity for Academic Liaison with Industry (GOALI) project deals with two important issues in polymer processing. Research will be focused on enhancing the control of the processing through the development a new methods for indirect measurement of the elongational viscosity of the polymeric material. In addition, efforts to optimize die channel geometry for polymer extrusion will be investigated in terms of the effects of elongational viscosity on the polymer flow in the die. In this project, strain-rate dependence of elongational viscosity will be determined by finding the optimal values of the four parameters in the Sarkar-Gupta elongational viscosity model such that the difference between the pressure loss predicted by a finite element simulation and the corresponding experimental data from a capillary or slit rheometer is minimized. The optimization model, which will be developed in this project, is expected to provide much better die design than the design obtained by using currently available software packages, which do not account for the elongational viscosity of a polymer. Even though this proposal involves optimization of extrusion dies, a successful completion of the proposed research will open the avenues for including the effect of elongational viscosity on design of the equipment for other polymer processing techniques involving elongation-dominated flows such as blow molding and fiber spinning. The software developed in this project will be used in a senior-level course to educate the students on importance of elongational viscosity in polymer processing. For the next three years, a graduate student will spend one month per year at The Dow Chemical Co. to conduct various experiments resulting in additional educational benefit from the project.