Assessment of nonlinear strain measures for extensional and shearing flows of polymer melts

摘要: From stress-strain experiments in extensional and shearing flows, nonlinear strain measures effective damping functions are derived for a polyisobutylene melt. The determined planar flow simple shear coincide. Experimental results compared with predictions of two molecular theories, the Doi-Edwards model stress function approach Wagner Schaeffer. Discrepancies between theories experiment lead to reconsideration classification flows. symmetry field is identified quantified as an important parameter influencing measure, unifying measure general flows polymer melts presented.