Normal stress differences behavior of polymeric particle suspension in shear flow

Abstract

Normal stress differences behavior of polymeric particle suspension in shear flow is investigated. The first normal stress difference (N1) in shear flow is found to mainly arise from the polymer matrix with a relaxation behavior altered by the presence of particles, which has its origin from the polymer chains trapped in the near-contact asymmetric regions of closely packed particles, while the second normal stress difference (N2) is dominated by the microstructure of particles at high volume fractions. It is proposed that the stress tensor in a polymeric suspension is the sum of a particle-contributed stress arising from the microstructure interaction and a polymeric matrix contributed stress with a relaxation spectrum altered by the particle microstructure. A simple model is proposed to describe how the relaxation behavior of a polymer matrix can be changed by the confinements of particles in suspension. © 2014 The Society of Rheology.