3. Results and Discussion
3.1 Curing Characteristics of EPDM/Bt composites
Fig. 1 and 2 both displayed the curing characteristics of vulcanizate EPDM/Bt composite. The optimum
curing time of vulcanizate EPDM/Bt increased with increasing Bt loading. The increase was attributed to the
adsorption of curative that arise from the presence of hydroxyl group at silicate layer of Bt clay. The similar
result was reported by Ansarifar et al, (2000) that also found the curing time of rubber delayed as the amount of
silica increased. The presence of hydroxyl group was reported able to disrupt the vulcanization process and
resulted in the increase in curing time and scorch time7
. Scorch time of EPDM/Bt composites shows increasing
trend with increasing amount of Bt only after incorporation of 30 phr Bt clay. At lower loading, a slight decrease
in scorch time was probably due to high surface area of Bt that promotes better heat distribution in rubber system.