Relaxation spectra of binary blends: Extension of the Doi-Edwards theory

¹  Department of Applied Mathematics, University of Twente - PO Box 217, 7500 AE Enschede, The Netherlands
²  Wageningen University, Department of Mathematics & Biometris - PO Box 100, 6700 AC Wageningen, The Netherlands
³  Eindhoven University of Technology, Faculty of Mathematics and Computer Science PO Box 513, 5600 MB, Eindhoven, The Netherlands
⁴  DSM Research, Material Science Centre - PO Box 18, 6160 MD Geleen, The Netherlands

Received: 19 April 2007
Accepted: 9 August 2007

Abstract

A molecular model is presented which allows the calculation of the stress relaxation function G for binary blends consisting of two monodisperse samples with arbitrary molecular weights. It extends the Doi-Edwards reptation theory (Doi M. and Edwards S. F., The Theory of Polymer Dynamics (Oxford Press, New York) 1986) to highly polydisperse melts by including constraint release (CR) and thermal fluctuations (CLF), yet making use of the same input parameters. The model reveals an explicit nonlinear dependence of CR frequency in the blend on the blend's molecular weight distribution (MWD). It provides an alternative way to quantify polydisperse systems compared to the widely used “double-reptation" theories. The results of the present model are in a good agreement with the experimental data given in Rubinstein M. and Colby R. H., J. Chem. Phys., 89 (1988) 5291.