MISCIBILITY AND MORPHOLOGY OF AB C-TYPE B LOCK-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 unit s has been prepared and studied by DSC and TEM. The enthalpy relaxatio n method has been used to the blends, Physical aging below T-g gives r ise to two separated enthalpy recovery peaks associated with PMMA bloc ks 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%) hyd roxyl contents show only one transition, This conclusion is in good ac cordance with that from TEM observation, Besides, for the blends, a su bstantial broadening of T-g is observed, which can be explained by ''t he segment-density gradient model'' proposed by Jiang et al..