Abstract: The miscibility and crystallization behaviour of blends of poly (ethylenc terephthalate) with poly(styrene-co-sodium acrylate) (ST-SA) were investigated by using DSCand FT-IRtechniques. The ionomer ST-SAwas found to have both nucleating and blending effects on PET. Not only the ionomer accelerated the crystallization of PET, but also improved the miscibility, forming a partial miscible two-phase system in the amorphous phase, Crystallinity data from both DSCand FT-IRmeasurements showed that the crystallinity of PETwas almost not affected by blending of the poly (styrene-co-sodium acrylate) at the equilibrium state. Avrami plot indicated that the secondary crystallization increased with the increase of the content of poly (styrene-co-sodium acrylate) in comparison with pure PET.

Key words: Poly(styrene-co-sodium acrvlatc), Poly(Ethylcnc teivphthalatc), Crystallization behaviour