SEARCH FOR A MODEL POLYMER BLEND

The thermodynamics of binary and multicomponent mixtures comprising po lymethylbutylene, polyethylbutylene, and polymethylbutylene-block-poly ethylbutylene was studied by small-angle neutron scattering. The Flory -Higgins interactions parameter, deduced from these measurements, was independent of blend composition, as well as molecular weight and mole cular architecture of the components, over the accessible temperature (27-201 degrees C) and pressure (0.01-0.86 kbar) range. At temperature s above 130 degrees C, the interaction parameter becomes independent o f pressure. These findings are compared with previous experimental stu dies on the thermodynamics of polymer blends. To our knowledge, this l evel of agreement with the Flory-Huggins theory has not been seen in a ny other polymer blend.