Surface phenomena and polymer miscibility of PVC/EVA blends

The study of the interface in polymer blends gives a riser full information about the thermodynamical miscibility of the system. The surface tension studies of the pure copolymers have shown that the acetate content plays the major role and this is also reflected in the interfacial tension of the PVC blends. The results show a direct relationship between the interface thickness and the vinyl acetate content in rite EVA copolymer. Interaction parameter values show an inversely related correlation. Calculated values obtained from the appropriate equations have shown small discrepancies from experimental data. The Flory-Huggins parameters, theoretically calculated by using recent theories which suppose that the vitreous transition is a true transition, are in good agreement with the values obtained from calorimetric measurements. Thermal stability and the degradation process were also studied. The experimental data showed a relationship between the thermogravimetric curves and the degree of interaction in the mixtures as compared to pure polymers that are consistent with microscopy analysis. Kinetic parameters and life time data of the mixtures were also calculated. (C) 1997 Elsevier Science Limited.