Fabrication and characterization of epoxidized natural rubber nanocomposites reinforced with mercapto-functionalized nanozirconia filler

The objective of this study was to develop a new type of nanocomposite material by reinforcing epoxidized natural rubber (ENR) through the integration of mercapto-functionalized nanozirconia (SH-ZrO2 NPs) synthesized using a ring-opening reaction. The ENR was prepared through the epoxidation of natural rubber (NR) using in situ generated performic acid from formic acid and hydrogen peroxide. The SH-ZrO2 NPs were pretreated and systematically embedded into the ENR matrix via a latex-casting process, resulting in ENR/SH-ZrO2 nanocomposites with enhanced properties. To prevent the accumulation of nanofillers in the ENR matrix, the surface of the nanozirconia was treated with 3-(mercaptopropyl)trimethoxysilane (MTS) to create mercapto-terminated ZrO2 NPs (SH-ZrO2 NPs) that were covalently attached to the ENR chains. The presence of MTS on the surface of the nanozirconia was confirmed by FTIR and thermogravimetric analysis (TGA) analyses. Structural and morphological characterization of the resulting nanocomposites was performed using standard techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), and TGA. The morphological studies indicated a uniform distribution of SH-ZrO2 NPs throughout the ENR matrix. Furthermore, TGA analysis revealed that the thermal stability of the nanocomposites was improved, as evidenced by a shift in the decomposition temperature to a higher value compared to neat ENR. Overall, this work demonstrates the potential of SH-ZrO2 NPs as an effective reinforcing agent in ENR-based nanocomposites, with improved thermal stability and homogeneity.