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.

A controlled esterification of starch to replace the OH moieties with bio-derived medium chain fatty acids, and the changes in the polymer structure and properties for material applications is investigated in this research. The esterification is conducted via a homogeneous esterification process using an activated lauric acid (C 12 ) in the presence of a base catalyst. The degree of esterification through the replacement of hydroxyl groups of starch was estimated using elemental analysis (EA) and proton NMR. The effect of the modification on the structural and material properties of the modified starch polymer is elucidated by evaluating the changes in morphology, network thermal stability, hydrophobicity, solubility profile, and thermal transition events. Scanning electron microscopy imaging reveals structural changes ranging from surface roughness to complete disruption depending on the degree of substitution. This is confirmed by XRD. Because of the esterification of starch, the resulting polymers become melt processable thermoplastic that forms a transparent film with an elastic storage modulus of up to 226 MPa at room temperature. This shows that the starch-fatty acid polymer can be used for various industrial and advanced material applications without any other plasticizers or modifiers. The final material is completely bio-based, and is expected to be biodegradable in the environment.Among the various modifications, thermoplastic starch has attracted the most attention because of the ease and low cost of the process. However, leaching out of external plasticizers, water sensitivity, premature aging caused by re-crystallization, brittleness, and too fast biodegradation 9-11 have limited Additional supporting information may be found in the online version of this article.

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