Compatibilization of natural rubber (NR) and chlorosulfonated polyethylene (CSM) blends with zinc salts of sulfonated natural rubber

Abstract

A rubbery ionomer of zinc salt of sulfonated natural rubbers (Zn-SNR) was synthesized and used as a new compatibilizerfor the blends of natural rubber (NR) and chlorosulfonated polyethylene (CSM). Epoxidized natural rubber (ENR)was also used for the preparation of NR/CSM blends. The effect of ionomer concentration on melt viscosity of the 50/50(%wt/wt) NR/CSM blends at different constant shear rates was characterized. It was found that the incorporation of ionomerincreased shear viscosity of the blends, indicating an increase in interfacial interaction between the NR and CSM. Themaximum shear viscosity was observed when the ionomer of 10% by weight of NR was added into the blends. The tensile,tear, oil resistant properties and morphology of the various 20/80 NR/CSM blends with and without the Zn-SNR and ENR atthe 10% wt of NR were examined. The 100% modulus, tensile strength, tear strength and oil resistance of the compatibilizedblends improved over those of the uncompatibilized blends. The blends compatibilized with the Zn-SNR showed higher levelsof improvement in modulus, tensile and tear strength than those of ENR. The tensile strength of 20/80 blends with the Zn-SNRand ENR compatibilizers increased by 38 and 30% over the corresponding neat blends. Furthermore, the addition of ionomerand ENR resulted in decreased domain of dispersed NR phase size and improved interfacial adhesion between the NR andCSM, indicating enhanced blend compatibility. These results suggest that the Zn-SNR is a new effective compatibilizer forNR and CSM blends