Effects of interphase interactions on the rheological properties of poly(ethylene terephthalate)-liquid-crystalline polyester blends

The rheological properties of poly(ethylene terephthalate) (PET) blends with a thermotropic liquid-crystalline (LC) polyester were studied and the physicochemical processes occurring at the interphase boundary between components in the me It were analyzed. The LC polyester was represented by a PET-p-hydroxybenzoic acid copolymer. Data of the optical interference microscopy revealed limited compatibility of the blend components and allowed the solubility of polyester in PET to be estimated. Rheological properties of the blends depend to a significant extent on the interphase boundary layer. The results of the capillary viscometry measurements indicate that the blend viscosity, exceeding the additive value in the entire range of concentrations studied, reaches maximum at a polyester content of similar to 70 wt %, Analysis of the IR spectra of the blends suggests that interchain exchange reactions take place at the interphase boundaries in the melt.