Preparation and characterisation of liquid epoxidised natural rubber in latex stage by chemical degradation

摘要

Preparation and characterisation of liquid epoxidised natural rubber in latex by chemical degradation was successfully carried out. The effect of certain parameters, such as surfactant concentrations, incubation time of ENR latex in the presence of surfactant and pH condition on the reaction efficiency were studied. Effect of degrading agent concentrations and drying temperatures of LENR were also investigated. The molecular weight, i.e., M-w and M-n, which was determined by gel permeation chromatography (GPC) and gel content of LENR were decreased gradually as the degrading agent concentrations increased. Moreover, the drying temperatures, ranging from 333 to 423 K showed no significant changes in epoxidation levels and epoxy derivatives, as the drying period decreased from 24 to 4 h. The resulting LENR were further characterised using Fourier transform infra-red (FTIR) spectroscope, nuclear magnetic resonance (NMR) spectroscope, differential scanning calorimeter (DSC) and field emission-scanning electron microscope (FE-SEM). The glass transition temperature, T-g of LENR, i.e., 252 K was increased compared with ENR, i.e., 248 K. Besides, the latex particles morphology of LENR were found to be more uniform and larger compared with ENR. The functional groups such as carbonyl as functional end group, hydroxyl, epoxy, ester and furan groups were increased after degradation of ENR to form LENR. This indicates that the presence of functional polar groups at the LENR backbone play an important role which brings about the distinguished characters and properties of LENR.