Synthesis and characterization of maleated ionomers via ring‐opening reaction of epoxidized styrene‐butadiene rubber with potassium hydrogen maleate and study of their behavior as compatibilizer

Abstract

AbstractA novel method for synthesizing maleate ionomer of (styrene‐co‐butadiene) rubber (SBR) from epoxidized SBR was developed. The epoxidized SBR was prepared via epoxidation of SBR with performic acid formed in situ by H2O2 and formic acid in cyclohexane. The maleated ionomer was obtained by ring‐opening reaction of the epoxidized SBR solution with an aqueous solution of potassium hydrogen maleate. The optimum conditions were studied. It was found that it is necessary to use phase transfer catalyst and ring‐opening catalyst for enhancing the epoxy group conversion. To obtain 100% conversion addition of dipotassium maleate is important. The product was characterized by FTIR spectrophotometry and transmission electron microcroscopy (TEM). The results showed that the product was really an ionomer with domains of maleate ionic groups. Some properties of the ionomer, such as water absorbency, oil absorbency and dilute solution behavior were studied. With increasing ionic groups, the water absorbency of the ionomer increases, whereas the oil absorbency decreases. The dilute solution viscosity of the ionomer increases abruptly with increasing ionic group content. The ionomer can be used as a compatibilizer for the blends of SBS and chlorosulfonated polyethylene (CSPE). Addition of a small amount of the ionomer to the blend can enhance the mechanical properties of the blends. 3 wt % ionomer based on the blend can increase the tensile strength and ultimate elongation of the blend nearly twice. The compatibility of the blends enhanced by adding the ionomer was shown by scanning electron microscopy. The blend of equal parts of SBS and CSPE compatibilized by the ionomer behaves as an oil resistant thermoplastic elastomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 792–798, 2006