Preparation and Characterization of Varying Carbon Black Particle Sizes on Poly(Epichlorohydrin) Elastomer: I. Improving of Curing Kinetics and Mechanical Properties

This study investigates the effect of carbon black (CB) particle size on the curing kinetics and mechanical properties of poly(epichlorohydrin) (H55) elastomers. The curing behavior was analyzed at 170 °C, 180 °C, 190 °C, and 200 °C, using first-order and nth-order kinetic models to determine the activation energy (Ea) and cure rate constant (k). Results indicate that CB significantly accelerates the vulcanization process, reducing the scorch time (ts2) and optimum cure time (t90) while increasing delta torque (ΔT) values, which correlates with improved cross-link density. The H55-N330 formulation exhibited the fastest cure rate and the highest delta torque, highlighting its superior curing efficiency. Mechanical testing revealed that adding CB enhanced stiffness, tensile strength, and modulus of elasticity, with the H55-N330 blend showing the highest elastic modulus (9.90 ± 1.07 MPa), approximately 13 times higher than CB-free H55 (0.70 ± 0.14 MPa). Swelling studies confirmed that CB increases cross-link density, leading to a 54% reduction in swelling ratio for the H55-N330 blend. Additionally, Shore A hardness values doubled with CB incorporation, while compression set values increased. Despite no significant differences in elongation at break, the addition of CB improved overall toughness and durability. These findings suggest that carbon black, particularly N330, significantly improves the curing kinetics, mechanical properties, and cross-link density of H55 elastomers, making them ideal for high-performance rubber applications in automotive, aerospace, and industrial sealing systems.