Poly(N,N-dimethylacrylamide)/copolymers of vinyl alcohol blends: effect ofthe comonomer

The miscibility behaviour of poly(N,N-dimethylacrylamide) (PDMA), with poly (ethylene-co-vinyl alcohol) (EVAL) of different compositions has been inves tigated and compared to that of the blends with poly(vinyl acetate-co-vinyl alcohol) (ACAL). Differential Scanning Calorimetry (DSC) results indicate that PDMA is miscible with EVAL78, EVAL68 and EVAL56 but immiscible with EV AL25, which has lower degree of hydrolysis. The limit of miscibility is low er in this case, indicating the influence of the vinyl alcohol content in m iscibility. Fourier transformed infrared spectroscopy (FTIR) studies of mis cible blends reveal the existence of specific interactions by hydrogen bond ing between hydroxyl groups in vinyl alcohol units of the copolymers and th e amide-carbonyl group in the PDMA, which appear to be decisive for miscibi lity. (C) 1999 Elsevier Science Ltd. All rights reserved.