EFFECT OF FLOW ON POLYMER-POLYMER MISCIBILITY

The effect of shear now on the miscibility of three model polymer blends has been studied by one-dimensional and two-dimensional light scattering, differential scanning calorimetry and in-situ optical microscopy. Shear was applied between parallel plates and the range of shear rates used was from approximately 0.5 s(-1) to 15 s(-1) Shear was observed to induce both miscibility and phase separation depending on the temperature and shear rate used. Under certain conditions, a large wave-like pattern was observed by in-situ microscopy which gave rise to elongated streaks in the two-dimensional light scattering patterns. These ''waves'' appeared to be independent of phase separation and instead seem to be consistent with the presence of fluid instabilities.