New Materials, Compounds and Applications

Metal oxides, particularly zinc oxide (ZnO), play a vital role as activators in the sulfur-based vulcanization of unsaturated rubber. ZnO significantly enhances the efficiency of vulcanization, improves the mechanical properties of the vulcanizate and reduces curing time. However, its widespread use raises environmental and safety concerns due to its toxicity and persistence. In an effort to find a safer, eco-friendly alternative, we synthesized two novel zinc chelates incorporating an azo dye and a Schiff base. These complexes were designed to release Zn²⁺ ions in a controlled manner, enabling effective crosslinking during vulcanization. Rheometric analysis revealed that these chelates influenced cure characteristics similarly to ZnO. Additionally, mechanical testing conducted before and after thermal aging demonstrated their ability to maintain desirable strength and elasticity. With further structural refinement, these zinc chelates show strong potential as sustainable and non-toxic replacements for conventional ZnO, aligning with green chemistry principles and regulatory trends in rubber manufacturing.