Nanodiamond-treated flax: improving properties of natural fibers

Synthetic fibers are used extensively as reinforcement in composite materials, but many of them face environmental concerns such as high energy consumption during production and complicated decommissioning. Natural fibers have been considered as an attractive solution for making composites more sustainable. However, they are generally not as strong as synthetic fibers. It is therefore of interest to investigate ways to improve the properties of natural fibers without compromising environmental issues. Here, we present a study of the moisture absorption and mechanical properties of flax that has been exposed to hydrogenated nanodiamonds through an ultrasonic dispersion treatment. Nanodiamonds are known to be non-toxic, unlike many other carbon-based nanomaterials. We show that nanodiamond-treated flax fabric has a lower moisture content (~ −18%), lower moisture absorption rate and better abrasion resistance (~ +30%). Single yarns, extracted from the fabric, show higher tensile strength (~ +24%) compared to untreated flax. Furthermore, we present a theoretical model for the nanodiamond fiber interaction, based on the Derjgauin–Landau–Verwey–Overbeek (DLVO) theory of colloid interactions. The simulations indicate that the mechanical properties improve due to an enhancement of the electrolytic force, dispersion force and hydrogen bonding of nanodiamond-treated fibers, which strengthens the cohesion between the fibers. We also apply the model to nanodiamond-treated cotton. The lower zeta potential of cotton increases the electrolytic force. Comparing the results to experimental data of nanodiamond-treated flax and nanodiamond-treated cotton suggests that the fiber’s zeta potential is critical for the improvements of their mechanical properties. Graphical abstract: [Figure not available: see fulltext.]