Preparation Of Epoxidized Acrylonitrile-Butadiene Rubber And Its Blending Modification

Chemical modification of rubber has been both of academic and industrial interest. Epoxidation of unsaturated rubber is among the most widely investigated rubber modifications. So far, some non-polar rubber such as natural rubber, polybutadiene rubber, styrene-butadiene rubber and ethylene propylene diene rubber have been epoxidized successfully. The introduction of epoxy group along the polymeric chain improves oil resistance, gas impermeability, good wet strip, adhesion to polar materials and so on. More importantly, this modification offers a chance for further reactive blending due to the great reactivity of epoxy group. For example, reactions with polar polymer containing carboxyl, hydroxy, amido or anhydride have been studied on epoxidized rubber . However, most of the epoxidation of rubbers are performed in latex or in organic solvent, and these reaction systems have the shortcomings of high cost, inconvenient operation and harm to environment. For the sake of making the epoxidation process of unsaturated rubber cleaner, safer, and more efficient, solventless reactive processing is chosen as a good method of producing the epoxidized rubber.The in-situ epoxidation of acrylonitrile-butadiene rubber (NBR) was successfully carried out in the reactive processing equipment of HAAKE rheometer with tert-butyl hydroperoxide and molybdenum trioxide. The structure of epoxidized NBR was characterized by ATR-FTIR. Reaction conditions such as temperature, reaction time and catalyst content were investigated. Epoxidation rate constant at different reaction temperature and apparent activated energy were given through kinetic analysis.ENBR was blended with carboxylic acrylonitrile butadiene rubber (XNBR) by mechanical blending process. ENBR/XNBR blends vulcanized at 180℃without any vulcanizing agent. ATR-IR spectra, DSC and vulcanization curves confirmed the self-vulcanization behavior of blends at the high temperature. The tensile strength, elongation at break and Shore A hardness of blends were improved with the reinforcement of filler.Epoxidized NBR/carboxylic carbon nanotubes composites were prepared by mechanical blending process. The vulcanization, dynamic mechanic and thermolysis properties were investigated. The results showed that carboxylic carbon nanotubes promoted the crosslink of the composites, and the composties showed the good vulcanization properties between 150~190℃.The storage modulus of the composites was influenced significantly by carboxylic carbon nanotube when the temperature was below the glass transition temperature. The thermal stability of the epoxidized rubber improved with the existence of carboxylic carbon nanotubes.