VCL#13 Incidence of Free Volume on the Formulation of Rheological Equations

Introduction to VCL#13 (Video) 2 min

Abstract

This Lecture describes the formulation of rheology at constant free volume, i.e. at constant (T-Tg) instead of classically done at constant T. We show that the classical formula of rheology (G'(w) and G"(w) proportional to w² and w at low w (the Maxwell's formula), or the 3.4 exponent for the molecular weight dependence of Newtonian viscosity), are in fact modified if one works at constant free volume (T-Tg(w)). We re-construct the rheological response at constant free volume from frequency curves obtained under isothermal conditions. The conclusion is that viscosity is not separable into a free volume term independent of a molecular weight term, as commonly admitted. At constant free volume the molecular weight dependence varies with a slope of 5.3, not 3.4.

Links to download VCL#13 (1h 45 min):inquire at newschoolpolymerphysics@gmail.com

Att: Dr. A. Beltzeki