Analysis of entrance pressure drop techniques for extensional viscosity determination

Abstract

V této práci byla navržena a testována speciální kapilára pro přesnější stanovení tahové viskozity, a to jak experimentálně tak teoreticky pomocí metody konečných prvků.

In this work, a novel (patent pending) orifice die design for precise extensional viscosity data determination from entrance pressure drop measurements has been developed and tested both theoretically (through Finite Element Analysis) and experimentally. It has been demonstrated that the proposed novel orifice die allows much more precise extensional viscosity measurements for polymer melts in comparison with conventional orifice dies. Moreover, it has been found that, for extensional strain hardening and extensional strain thinning polymer melts, the corrected Cogswell model and Binding/Gibson model should be preferred, respectively. Otherwise, the extensional viscosity determination can be rather erroneous.