Velankar Strain recovery of model immiscible blends : effects of added compatibilizer

Immiscible homopolymers are often blended mechanically to obtain blends with properties significantly superior to those of the component polymers. The creep recovery of such blends was studied in the previous paper, henceforth referred to as I. Surface-active compatibilizers are commonly added to such blends to improve blending of the immiscible phases and to improve the mechanical properties of the resulting blends. This paper continues previous research on the effect of such compatibilizers on the rheological properties of two-phase blends (Velankar et al. 2001a, b, 2004a; Van Hemelrijck et al. 2004). Following the philosophy of keeping bulk rheology as simple as possible in order to focus on interfacial effects, all experiments are conducted on ‘‘model’’ blends of nearly-Newtonian polymer melts. Moreover, at sufficiently large concentrations, the compatibilizer can modify the rheological properties of the bulk phases. In order to avoid this complication, experiments are restricted to blends with only small amounts of compatibilizer (1 wt% or less) at which their effects on bulk rheology are negligible (Velankar et al. 2004a). Our previous research with such model compatibilized blends was restricted to droplet-matrix blends Jun Wang Sachin Velankar Strain recovery of model immiscible blends: effects of added compatibilizer