Vulcanization of natural rubber latex with low energy electron accelerator

Radiation-induced cross-linking of natural rubber (cis-1,4-polyisoprene) dispersed as microscopic particles in an aqueous medium, called RVNRL (radiation-vulcanization of natural rubber latex), is an excellent vulcanization process: free from N-nitrosoamines, very low cytotoxicity, less protein content, easy degradation in the environment, transparency and softness, and less formation of SO2 when incineration. These arise from the process without dithiocarbamates, sulfur and zinc oxide that are essential chemicals for the conventional process but the radiation process needs Co-60 or high-energy accelerator facilities with bio-shielding which result in high cost. Thus, RVNRL with a self-shielding low energy accelerator was proposed and the inevitable disadvantages such as high absorption by air and low penetration in latex were overcome by employing specially designed irradiation system with a rotating drum irradiator or a belt conveyer type irradiator and others that are described in this report. From the pilot plant operation it was concluded that low energy electron accelerator is a practical radiation source for RVNRL. (S. Ohno)