MISCIBILITY AND MORPHOLOGY OF AB/C-TYPE BLOCK-COPOLYMER HOMOPOLYMER BLENDS .3. ENTHALPY RELAXATION OF THE BLENDS

A series of blends composed of block copolymer PI-b-PMMA and modified polystyrene PS(OH) with different contents of hydroxyl-containing units has been prepared and studied by DSC and TEM. The enthalpy relaxation method has been used to the blends, Physical aging below T-g gives rise to two separated enthalpy recovery peaks associated with PMMA blocks and PS(OH) respectively far the blends with lower (0 and 1.0 mol%) hydroxyl contents. while the blends with higher (1.7 and 5.0 mol%) hydroxyl contents show only one transition, This conclusion is in good accordance with that from TEM observation, Besides, for the blends, a substantial broadening of T-g is observed, which can be explained by ''the segment-density gradient model'' proposed by Jiang et al..