Measurements of the Composition and Molecular Weight Dependence of the Flory−Huggins Interaction Parameter

Abstract

The phase behavior of binary blends of polyolefins is studied using small-angle neutron scattering. Component 1 is polyisobutylene (PIB), and component 2 is deuterated polybutadiene (dPB). Blends of these polymers are known to exhibit lower critical solution temperatures. The scattering intensity profiles from homogeneous PIB/dPB blends are fit to the random phase approximation to determine χ, the Flory−Huggins interaction parameter. We demonstrate that χ depends on temperature, blend composition, and component molecular weights.