Local versus integral measurements of the extensional viscosity of polymer melts

摘要: A simple method to measure the local extensional properties of polymer melts using a modified Munstedt rheometer is demonstrated. Real time imaging specimen during extension process provides rates strain as function coordinate along specimen. Simultaneously, stresses are assessed by measurements sample diameter and synchronous force exerted on bottom plate rheometer. The quantitative homogeneity deformation states via kinematic dynamic fingerprint process. Test experiments geometrically homogeneous samples reveal good level agreement between integral transient viscosity thus validate method. Furthermore, this technique employed assess quantitatively impact inhomogeneities viscosity. It concluded that in case initially inhomogeneous samples, depend strongly position usual highly unreliable unrepeatable. Higher Hencky indicate that, although inhomogeneity increases systematically experiments, data remain reliable long were reasonably their initial state.