PHASE-DIAGRAM FOR IRREGULAR AND NONSYMMETRICAL CROSS-LINKED POLYMER BLENDS

We consider a blend made of two types of polymers, A and B, of differe nt chemical nature. At high temperature, the homogeneous mixture is cr oss-linked. As the temperature is lowered, the two species try to segr egate but are kept together by the cross-links. We show that for inhom ogeneous, non-regular and non-permanent cross-links, there is a comple te segregation at low temperatures, if the system is just weakly cross -linked, and partial segregation otherwise. We also demonstrate that t here is no phase transition between the homogeneous phase and the micr ophase for non-symmetric systems. Our analysis is checked with the exp eriment. (C) 1998 Elsevier Science B.V. All rights reserved.