[Study of the miscibility of polymer blends by inverse gas chromatography]

An investigation was made on the thermodynamic parameters chi'23 of the polymer system polyvinyl chloride (PVC)/ethylene-vinyl acetate copolymer(EVA) by inverse gas chromatogrphy(IGC), and the miscibility of the blends was studied by using chi'23 as judging foundation, and it was preliminary discussed the relation between chi'23 and composition of the blend, and molecules-chain structure of polymer, and temperature. The influence of the property of probes on chi'23 was also discussed. Results showed thermodynamic miscibility for PVC/EVA blend was accurately and directly indicated by chi'23. Experimental data confirmed the conclusion reported by other studies. It was immiscible for blends of which the acetate content was lower in EVA copolymer. The experimental temperature was favorable for improving miscibility of blends. The medium content in EVA copolymer resulted in partial miscibility for the blend, but the phase-seperation appeared when the experimental temperature was raised. This is in agreement with the previous studies on polymer blends. The apparent interaction parameter was found to be dependent on the chemical nature of the probe, the values of chi'23 were very different, but most experimental data show the same general trend with temperature and composition of blends.