Moving Beyond Organosilanes: Tris(hydroxymethyl)aminomethane as a Superior Surface Modifier for Zirconia in NBR Composites

Abstract

This study investigates the potential of Tris(hydroxymethyl)aminomethane (Tris) as a surface modifier for zirconia to enrich the ultimate properties of nitrile rubber (NBR) composites. By substituting commonly used organosilanes with Tris to modify the surface of zirconia, significant improvement in zirconia particle dispersion within the NBR matrix is achieved, leading to a stronger rubber-filler interaction. Scanning electron microscopy (SEM) images reveal a finer dispersion of zirconia particles, facilitated by the efficient surface modification of zirconia by Tris. Rubber-filler interactions, examined through the Lorenz-Park principles and viscoelastic properties, demonstrate that Tris modification reduces the surface energy of zirconia, enhancing its dispersibility and improving interfacial bonding between the rubber and the zirconia due to increased reactivity. This causes significant improvement in mechanical and other composite properties such as thermal stability, oil resistance, flame retardancy for the Tris modified in situ zirconia filled composites. Among the compositions examined, the composite containing 2 phr of Tris and 30 phr of zirconia (In-2T-Zr-30) exhibits a substantial improvement in tensile strength, over 20 times higher than that of the unfilled sample. These findings highlight the potential of Tris as an effective surface modifier for zirconia, enhancing filler performance and offering a promising alternative to organosilanes in the development of high-performance nitrile rubber composites