The characterization and thermal stability of purified epoxidized natural rubber with 25 mol% epoxidation (ENR-25) and treated epoxidized natural rubber with 25 mol% epoxidation / Zirconium dioxide (ENR-25/ZrO2) Composites were studied using Fourier transform infrared spectroscopy (FTIR) and thermo gravimetric analysis (TGA). The ENR-25/ZrO2 composites were treated with acetic acid and two different loading (50 and 100 mg) of ZrO2 were used to form the composites. FTIR results show the ester (C-O) peaks at 1000-1300 cm-1 due to the presence of acetic acid in the composites. The disappearance of epoxide peak at range 880-875 cm-1 indicated that ZrO2 have formed hybrid bonds with opened epoxide rings. The both ENR/ZrO2 composites showed 2 major thermal degradation steps (304 - 489°C and 493 - 551°C) for 50 mg ZrO2 loading and (306 - 497°C 512 - 581°C) for 100 mg ZrO2 loading indicating that the thermal stability of the composites have improved.
