Effect of Lead and Borax Powder on the Swelling Behavior of EPDM Rubber Composite in Toluene

Synthetic EPDM reinforced, with carbon-black (N-220) as filler, was cured by sulfur with other ingredients. Three groups of samples were prepared. The 1st group contains different concentration (phr) of lead, the 2nd group contains different phr of borax, and the 3rd group contains 25phr borax and different phr of lead. The swelling test was carried out for all samples in the toluene. Swelling parameters such as the rubber volume fraction, crosslinking density, swelling index etc. were calculated. The results showed that the crosslinking density increase as the concentration of lead increase and the ability of the sample to swell decrease. In contradiction, it is observed that the samples contain different phr lead and 25phr borax the crosslinking density decreased, and the samples swelled to high extent. Adding borax only to the samples had no considerable effect on the crosslinking density and on the swelling behavior. Also, the swelling index has been obtained to all samples. The result showed that n similar to 0.5 which Fickian diffusion. Two models (Kraus and Cunnen - Russel) were applied to test the filler rubber interaction. The models give a good result with the experimental data. One way ANOVA statistical analysis was applied to find out more information about the effect of lead, borax and both of them on the swelling behavior through the calculated coefficients. The statistical results confirmed the practical results, and consequently the post-test Tukey was used to assess the significance of differences between pairs of group means.