Effects of nanocrystalline calcium oxide particles on mechanical, thermal, and electrical properties of EPDM rubber

In this research, the effect of calcium oxide (CaO) nanocrystalline particles filled ethylene propylene diene monomer (EPDM) rubber composites is investigated, at different weight percentages (1.0, 2.0, 4.0, and 8 wt%) of CaO nanocrystalline particles using two methods of mixing. In one case conventional mixing on twin roll-mill was used, in the other case ultrasonic mixing as a pre-mixing was applied. CaO particles are synthesized by the precipitation method. The average crystallite size of CaO is 100 ± 20 nm. Adding CaO nanocrystalline particles increases the thermal stability of EPDM and the glass transition temperature. The hardness of EPDM rubber gradually increases with increasing the amount of CaO particles, the maximum hardness 64.2 observed in 8 wt% of CaO particles for both cases almost 26% higher than neat EPDM. Tensile strength decreases, while the maximum % modulus of the ultrasonic mixed sample was 1.48 MPa which is 24% higher than EPDM.