Melting of the blends between syndiotacticity-rich and atactic poly(vinyl alcohols

A highly syndiotacticity-rich (s-) poly(vinyl alcohol) (PVA) of a 66 s-dyad % [s(66)-PVA] was blended by a solution method with atactic (a-) PVA of a 5 5 s-dyad% and another s-PVA of a 61 s-dyad%. The s(66)-PVA was shown to be able to produce cocrystallized phases with the other PVAs by investigating the melting behavior. The melting temperature and heal of fusion changed wi th the average syndiotacticity that was controlled by blending two PVAs wit h various compositions. As a result, the maximum melting temperature and th e maximum heat of fusion appeared when the average rr triad value was 0.40, indicating that the high nucleation rate due to the high syndiotacticity c omponent decreased the morphological factors such as the crystal size or th e order of molecular packing, (C) 1999 Elsevier Science Ltd. All rights res erved.