EFFECT OF GAS-PRESSURE ON THE SOLUBILITY AND DIFFUSION OF POLYBUTADIENE IN POLYSTYRENE

Tracer diffusion of 3000 g/mol perdeuterated polybutadiene (dPB) into high molecular weight polystyrene (PS) was measured with forward recoi l spectroscopy (FRES) in the temperature range from 90 to 110-degrees- C in the presence of argon and helium pressures up to 11.3 MPa. The di ffusion coefficient for dPB in PS at 107-degrees-C increases from 1.2 X 10(-13) to 8.7 x 10(-13) cm2/s as the argon pressure is increased fr om atmospheric pressure to 11.3 MPa. When helium is the pressurizing m edium, the diffusion coefficient for dPB in PS at 107-degrees-C decrea ses from 1.2 x 10(-13) to 3.7 x 10(-14) cm2/s as the pressure is incre ased from atmospheric pressure to 11.3 Wa. The results are explained i n the framework of competing hydrostatic pressure and plasticization e ffects. The solubility of dPB in PS is independent of pressure, irresp ective of the gas used as the pressurizing medium.