Miscibility and surface segregation in PVC/polyester blends—The influence of chain architecture and composition

Four poly(butylene adipate) (PBA) polyesters, the structure ranging from linear to highly branched, were synthesized and solution casted with poly(vinyl chloride) (PVC) in 20 or 40 wt % concentrations to evaluate the influence of polyester chain architecture on miscibility, surface segregation, and mechanical properties. The miscibility of PVC and polyesters is based on specific interactions between the carbonyl group in the polyester and PVC. These interactions cause a shift in the carbonyl absorption band in the FTIR spectra. The shifting of the carbonyl absorption band was more significant for all the 40 wt % blends compared with the blends containing 20 wt % of the same polyester. In the 20 wt % blends surface segregation and enrichment of polyester at the blend surface increased as a function of branching. However, all the films containing 40 wt % of polyester had similar surface composition. This is explained by better miscibility and stronger intermolecular interactions in the 40 wt % blends, which counteract the effect of branching on the surface segregation. High degree of branching resulted in poor miscibility with PVC and poor mechanical properties. A linear or slightly branched polyester structure, however, resulted in good miscibility and desirable blend properties. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1552–1563, 2007