LIQUID LIQUID-PHASE SEPARATION IN MELTS OF BLENDS OF LINEAR WITH BRANCHED POLYETHYLENES - MORPHOLOGICAL EXPLORATION OF THE PHASE-DIAGRAM

The liquid-liquid phase separation in blends of linear and branched polyethylenes has been observed using a morphological technique. The results confirm our previous conclusion that the phase-separated region of the phase diagram has a closed loop shape. We have also been able to demonstrate that the phase separation occurs at the same temperature on heating and cooling and hence argue that it represents an equilibrium phase boundary. The process of phase separation has been studied by observing changes in the shape and sizes of the phase-separated regions with time. In some cases, we argue that it is possible to distinguish between morphologies caused by liquid-liquid phase separation which occurred through nucleation and spinodal decomposition.