A Carboxylated Nitrile Butadiene Rubber Latex Film with Synergistically Enhanced Water-Based Lubricity and Tensile Strength: Fabrication and Characterization

To address the inherent trade-off between high wet friction and poor mechanical properties in carboxylated nitrile butadiene rubber (XNBR) films, this study introduces a layered silicate (bentonite) as a dual-functional lubricating-reinforcing additive. Unlike the conventional linear polymer anionic polyacrylamide (APAM), which has limited efficacy, bentonite exhibits superior performance attributed to its unique two-dimensional (2D) nanosheet structure. The mechanism is twofold: under shear stress, the hydrated nanosheets align to form a highly efficient, low-friction interface; simultaneously, these rigid nanosheets act as a reinforcing filler within the matrix, enhancing mechanical strength through stress dissipation and microcrack inhibition. Consequently, the bulk incorporation of bentonite resulted in a remarkable 38% increase in tensile strength, coupled with a significant 48% reduction in the wet coefficient of friction. This work elucidates an effective mechanism for synergistically improving both surface and bulk properties of a polymer using inorganic nanosheets, offering a new strategy for the design of advanced functional composites.