DETERMINATION OF CHEMICAL AND MECHANICAL PROPERTIES OF HYDROGENATED NATURAL RUBBER SYNTHESIZED AT SEMI PILOT SCALE

Abstract

The use of natural rubber goods for outdoor based applications like elastomeric bearing pads is limited by their low thermal oxidative resistance. This weakness could be improved by chemical modification such as diimide transfer hydrogenation of natural rubber in the latex phase. Diimide is a reactive hydrogen donor substance which is generated in situ by oxidation of hydrazine hydrate with hydrogen peroxide. In this research, the hydrogenated natural rubber was synthesized by diimide transfer hydrogenation at semi pilot scale at a capacity of 2.5 kg latex concentrated/batch. The aim of the research was to determine the chemical and mechanical properties of hydrogenated natural rubber obtained from the semi pilot scale reaction. Unmodified natural rubber was used as a control. The result of the evaluation showed that the diimide substance produced from a higher hydrogen peroxide concentration could effectively convert unsaturated C double bonds into saturated C single bonds in the natural rubber molecular chain. The improvement of the thermal oxidative resistance is illustrated by a higher plasticity retention index and less change in hardness and elasticity for hydrogenated natural rubber prepared from 35 phr hydrogen peroxide. This new type of modified natural rubber could potentially be a substitute for synthetic rubber used in the manufacturing of elastomeric bearing pads.

Keywords: Diimide, hydrogenation, natural rubber, themal oxidative resistance