SOLUBILITY AND DIFFUSION OF POLYBUTADIENE IN POLYSTYRENE AT ELEVATED-TEMPERATURES

The thermally-induced diffusion of low molecular weight perdeuterated polybutadiene (dPB) in polystyrene (PS) was measured with forward recoil spectroscopy (FRES). Diffusion coefficients were determined for 3000 g/mol dPB penetrating into a 350 000 g/mol PS matrix in the temperature range 97-115-degrees-C. The diffusion coefficients vary from 10(-15) to 10(-12) cm2/s. The apparent activation energy is 99 kcal/mol. Solubility limits for dPB in PS at temperatures ranging from 105 to 160-degrees-C were also determined with FRES. The results were used to construct a portion of the binodal curve for this polymer system. The derived value of the Flory-Huggins interaction parameter, chi, is 0.055 and 0.048 at 105 and 160-degrees-C, respectively.