APPARENT SLIP AT A POLYMER-POLYMER INTERFACE

We consider a planar interface between strongly-segregated homopolymer s subjected to steady shear in the plane of the interface. We develop a constitutive equation for stress relaxation in an inhomogeneous syst em for chains obeying Rouse dynamics. Using this equation, the interfa cial viscosity for a symmetric blend is found to be zeta b(2)/(6 chi n u(0)) in agreement with a scaling prediction due to de Gennes, where z eta is the bead friction coefficient, b is the segment length, nu(0) i s the segment volume and chi is the Flory-Huggins interaction paramete r driving the phase separation. We generalize our results to asymmetri c blends and describe a phenomenological extension to entangled melts.