CO-PHASE CONTINUITY IN IMMISCIBLE BINARY POLYMER BLENDS

Methods of microscopic observation and macroscopic characterization ha ve been developed for determining the co-phase continuity in immiscibl e binary blends. After selective dissolution of the component polymers , the morphologies of microscopic observation are consistent with the results of macroscopic observation and weight percentage determination . By using these methods, the relationship between co-phase continuity , composition and blending time has been explored for two immiscible b inary polyblends with different viscosity ratios (lambda), polyamide 6 /polyethersulfone (PA/PES, lambda = 0.03) and poly(butylene terephthal ate)/polystyrene (PBT/PS, lambda = 1). Both blend systems show a simil ar dependence of co-phase continuity on the composition and mixing tim e. That is at short mixing time (for example, 2 minutes), the co-phase continuity takes place in a wide composition range. With increasing b lending time, the composition range of co-phase continuity becomes nar row, and finally shrinks to one point. After a long enough mixing time the co-phase continuity region will occur only at a volume fraction o f 50/50, no matter what the viscosity ratio of the blend is. (C) 1997 Elsevier Science Ltd.