Synergistic Cross-linking and Reinforcing Enhancement of Rubber Latex with Cellulose Nanocrystals for Glove Applications

The effect of cellulose nanocrystals (CNCs) on the reinforcing, cross-linking, and solvent barrier properties of lightly cross-linked natural rubber (NR) latex films for dipped goods applications were investigated. Predispersed CNCs, activating, and curing agents were mixed with natural rubber latex and allowed to mature for 2 h. Films were then prepared from the matured latex via dipping and solvent casting processes. The incorporation of CNCs in the NR latex led to remarkable improvement in tensile strength and modulus with progressively thinner films. An increase in the cross-linking density of the rubber films were observed as a result of the incorporation of CNCs, which was observed from proton nuclear magnetic resonance analysis, and toluene swelling studies. This was likely attributed to an enhanced dispersion of the zinc oxide (ZnO) used as a cross-linking activator as observed from electron dispersive X-ray spectroscopy (EDX). A possible mechanism for the improved dispersion of ZnO in the latex in the presence of CNCs was the formation of Zn–CNC complexes. Higher cross-linking densities also led to lower water absorption over a prolonged time period. The nanocomposite thin films showed low permeability to a nonpolar solvent vapor, such as tetrahydrofuran (THF), but increased permeability to water vapor. A practical application of the observed barrier properties in dipped rubber goods could be in gloves, where permeation of perspiration from hands, is allowed while preventing the passage of nonpolar solvents.