Small-angle neutron scattering from pressurized polyethylbutylene/polymethylbutylene blends

Model polyolefins with molecular weights of about 200,000 g/mol were synthesized. In situ pressure was applied to the sample using a hydraulic pressure cell. The pressurizing fluid compresses the 1 mm-thick sample up to 1 kbar pressures. Small-angle neutron scattering (SANS) measurements were performed to characterize the phase transition lines and their changes with pressure and the phase separation kinetics. Pressure was observed to shift the phase boundary lines upward in temperature, that is, pressure favored demixing.