Chelation of Zinc Ions by <scp>EDTA</scp> : A Novel Strategy for Stabilizing the Vulcanization Degree of Prevulcanized Natural Rubber Latex

ABSTRACT Many natural rubber latex (NRL) products are produced using prevulcanized latex. Both insufficient and excessive vulcanization can adversely affect product quality. However, the degree of vulcanization in latex continues to increase during storage. Therefore, maintaining a stable vulcanization level in prevulcanized natural rubber latex throughout storage is critical for producing high‐quality latex products. In this study, EDTA was used to chelate the active zinc ions released from the decomposition of zinc oxide during storage, thereby enhancing the stability of the vulcanization degree in prevulcanized NRL over time. The results indicate that the addition of 0.5 phr EDTA effectively stabilizes the vulcanization degree of prevulcanized latex during storage, with minimal changes in the equilibrium swelling index. EDTA/NRL films showed no cracking from over‐vulcanization, and after 90 days of storage, their mechanical properties remained comparable to films without EDTA (tensile strength: 25.6 vs. 23.49 MPa; tear strength: 37 vs. 37.03 kN/m). Raman spectroscopy revealed changes in crosslink density during storage, elucidating the mechanism by which EDTA stabilizes vulcanization and maintains film mechanical integrity. EDTA had minimal impact on colloidal properties and thermal stability, and even at low dosages, it provided effective stabilization, demonstrating practical advantages for industrial processing.