Preparation of liquid epoxidized natural rubber in latex stage by chemical degradation

Abstract

Low molecular weight epoxidized natural rubber (ENR) may have potential to become one of the advanced green materials since it is prepared from the renewable resource of natural rubber. Low molecular weight ENR or liquid epoxidized natural rubber (LENR) was prepared by degradation of ENR latex using redox reagents in the presence of a surfactant. Preliminary studies on the optimization of degradation with regards to the starting material and reaction parameters were carried out. The results showed that the ENR latex of pH 8.0 and surfactant concentration of 2-3 w/w% of the starting material (ENR latex) were suitable to prepare LENR, in which this condition was significantly contributed to the decrease of molecular weight of LENR, i.e ±10 000 g/mol (Mn). Furthermore, the molecular weight decreased as the chemical concentrations increased. Comparable properties to ENR (starting material), the molecular weight and gel content of LENR was markedly reduced, the glass transition temperature of LENR was slightly increased, i.e. -21 °C, whilst the epoxidation level was about similar, 50 ± 5 mol%.