Blends of poly(vinyl butyral-co-vinyl alcohol) and poly(ethylene terephthalate-co-ethylene naphthalate): Thermal, mechanical, and morphological properties

The miscibility behavior and morphology of a series of poly(vinyl butyralco -vinyl alcohol) (PVBA) copolymers containing 29, 52, 76, and 88 mol % of vi nyl alcohol units with poly(ethylene terephthalate-co-ethylene naphthalate) (PETN) was investigated by DSC and SEM. Blends of the PETN with PVBA were prepared by coprecipitation from a chloroform/o-chlorophenol (20/80 wt %) m ixture solvent. It was found that PVBAs with different vinyl alcohol conten t will form an immiscible phase with the amorphous PETN in the solution-cas t films. Also, PETN and PVBA with 29 mol % vinyl alcohol (PVBA-29) are not miscible within the whole composition range. The glass-transition temperatu res of the blends were higher than those of the two-component polymers. The values of the tensile properties of the blend films were also better than those of the original copolymer films. (C) 2001 John Wiley & Sons, Inc.