A linear viscoelastic model of matrix/core-shell modifier polymer blends

Abstract

Palierne's emulsion model is utilized to develop a linear viscoelastic model for the rheological description of matrix/core–shell modifier blends with strong adhesion at the particle/matrix interface. In this model, the total stress is assumed to be the sum of a mean stress and an additional mean stress. The mean stress due to the viscoelastic effects in microflows of matrix polymers around the dispersed phase is formulated according to the Palierne approach. The additional mean stress due to strong adhesion at the interface is expressed with the three-parameter Maxwell model. The rheological behavior of the matrix chains trapped by the shell of the modifier is described by the introduction of the frequency-dependent parameter ξ and its evolution equation. By definition, ξmax changes from zero to unity as the frequency increases. The additional mean stress predominates at low frequencies, and as the frequency increases, the contribution of the mean stress to the total stress becomes more significant. The experimental data obtained for polymethylmethacrylate/core–shell polybutylacrylate blends confirm that the model developed in this study describes the rheological properties of incompatible blends more properly than the Palierne model. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 942–953, 2000