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