Radiation Vulcanization of Natural Rubber Latex with Diacrylates

Abstract

Diacrylate such as 1, 6-hexanediol diacrylate (A-HD), neopentyl glycol diacrylate (A-NPG) and 1, 3-butylene glycol diacrylate (A-BG) has a strong sensitizing effects on radiation vulcanization of natural rubber latex. The latex containing diacrylate tends to coagulate due to low solubility of diacrylate in the latex rubber particles. The stability of the latex was improved by the addition of ligroin which brings about increase of solubility of diacrylate in rubber particles. Among diacrylates A-HD shows excellent sensitizing effect in the presence of 20 phr of ligroin. However the presence of ligroin is liable to cause air pollution by evaporation during the drying of the irradiated latex. 2-ethylhexyl acrylate (2EHA) which easily converts to non-volatile polymers by irradiation was found to be able to substitute for ligroin as a stabilizing solvent. The stabilizing effect of 2EHA is higher than that of ligroin. The tensile strength of the vulcanized latex rubber decreased with increasing the amount of 2EHA. The dose for radiation vulcanization decreased by the addition of 2EHA, even it has only one C=C double bond in the molecules. The maximum tensile strength of radiation vulcanized latex rubber was obtained at a dose of 30kGy when 5 phr of 2EHA was added to the latex.