Effect of Non-Rubber Components on Properties of Sulphur Crosslinked Natural Rubbers

Abstract

Non-rubber components (mainly proteins and lipids) in natural rubber (NR) play important roles for controlling the properties of NR. Crosslinking process creates intermolecular chemical bonds in order to obtain a three-dimensional network, resulting in more elastic rubber. Sulphur crosslinking is the most popular method and is applied in the present study. Two types of NR were prepared, namely, whole natural rubber (WNR) and purified natural rubber (PNR). PNR was deproteinized by centrifugation method and then acetone extraction. These rubbers were crosslinked by an efficient vulcanization (EV) system. They were cured for three curing times (1x t 90 , 2x t 90 , 3x t 90 ) at 150°C. WNR presents shorter curing time than PNR because there are some phospholipids and proteins which are natural accelerators for curing reaction. The presence of non-rubber components seems to play a major role on crosslinking density and adhesion phenomenon for rubber/glass system. AFM images of WNR show more heterogeneity and roughness compared to PNR.