Research On Urea Concentration Effect In The Radiation Vulcanization Of Natural Rubber Latex
Radiations vulcanization of natural rubber latex (RVNRL) has been developed extensively through various research and development programme. This holds important benefits for rubber industries in Southeast Asia and the Pacific Region. Myanmar also develops more and more rubber plantation and many rubber raw materials are processed to manufacture medical products, household items and industrial mechanisms. In this paper, advanced and effective radiation vulcanization technique is utilized to introduce the technology in rubber industries in Myanmar. It uses gamma radiation to initiate vulcanization, a process that chemically bonds molecules to promote rubber elasticity and strength. In the present study, the radiation effect on the vulcanization of natural rubber latex and the synergistic effect of urea addition along with n-butyl acrylate (n-BA) sensitiser on the crosslinking density and physical properties of RVNRL film have been investigated. Acrylate monomer was used in order to reduce the radiation dose required to vulcanize natural rubber latex, originally 300 kGy to 15 kGy. However, there is still a need to further reduce the dose requirement without increasing n-BA concentration. The way to fulfil the requirement is the using of urea. Therefore the various concentration of urea (0.1, 0.2, 0.3, 0.4 and 0.5) (phr) was used. Tensile strength, elongation at break, modulus at 500%, swelling ratio, gel content and crosslinking density were determined. Tensile strength and modulus at 500%, gel content and crosslinking density were found increasing with absorbed dose, as well as the proportion of monomer concentration in the rubber phase in presence of urea. The radiation dose for better cross-linking of natural rubber latex with six parts per hundred rubber (phr) n-BA was 15 kGy absorbed dose from the results. The results show that by addition of 0.3 parts per hundred rubber (phr) urea to the latex before irradiation, the crosslinking density and tensile strength increases respectively.
Keywords- Natural rubber latex, N-butyl acrylate, Urea, Gamma radiation, Vulcanization, Tensile strength, Crosslinking density