STUDY OF COMPATIBILITY OF POLY(ETHER URETHANE UREA) ELASTOMER WITH VINYL CHLORIDE POLYMERS

The effect of the chemical structure of vinyl chloride-based polymers (VCP) on their compatibility with poly(ether-urethane-urea) elastomer (PUU) has been studied. Among a variety of VCP, poly(vinyl chloride) (PVC), chlorinated PVC (CPVC), vinyl chloride/vinyl acetate copolymers with 15 wt.% (A-15 copolymer) and 25 wt.% (A-25 copolymer) of vinyl acetate moieties were used. PUU/VCP blends were obtained by solution casting technique using N,N-dimethylformamide as solvent. Observation of the structural features of the polymer-polymer blends showed the appearance of donor-acceptor interactions between nitrile moieties of rigid segments of PUU and polar groups of VCP at the interface. Using DSC, the formation of a mixed phase was observed in the PUU blends with 30 wt.% PVC or A-15 copolymer, and the composites are characterized by three glass relaxation transitions. With increasing PVC or A-15 content up to 50-70 wt.%, the compatibility of the components decreases and the blends form a biphasic microheterogeneous structure. Increasing the chlorine content in CPVC enhances the compatibility of the polymers in the blends. These composites are characterized by a single broad glass relaxation transition over the entire concentration range. The experimentally determined glass transition temperature (Тс) of PUU/40CPVC (a number indicates a content of VCP in wt.%) is higher than the theoretical one calculated using the Flory-Fox equation. This fact indicates the formation of an interpolymer complex in the blend. Increasing the content of polar vinyl acetate moieties in VCP thermoplastics up to 25 wt.% (А-25 copolymer) results in a decrease of its compatibility with PUU elastomer. Finally, in these formulations the phase separation processes are activated and the blends are characterized by a biphasic structure in all composition range. A comparative analysis of the dependence of density, tensile strength and residual strain on the composition of the blends confirms the significant influence of the chemical structure of VCP on the interfacial adhesion, and the maximum strengthening of the composite is observed in the PUU/CPVC blends stabilized by stronger donor-acceptor bonds.