Tensile properties and wear resistance of epoxy nanocomposites reinforced with cellulose nanofibers

Cellulose nanofibers (CNFs) were prepared from sugarcane bagasse and used as reinforcement in epoxy nanocomposites. To obtain CNFs, the cellulose was bleached with sodium chlorite, hydrothermally hydrolyzed with 5% w/v oxalic acid under pressure of 800 psi at 100 °C in a microwave reactor, and homogenized using a mechanical homogenizer. The diameters of CNFs determined from field emission scanning electron microscope (FE-SEM) vary from 8 to 86 nm. The percentage crystallinity obtained from X-ray diffractometry is 62.8%. The epoxy was mixed with the prepared CNFs and cured at room temperature for 7 days. The effects of CNFs concentrations (0, 0.5, 1.0, 3.0, 5.0 and 10.0 wt%, dry basis) on the tensile properties and scratch resistance of the nanocomposites were investigated. Young’s modulus and tensile strength increased with an increasing CNFs loading up to 3 wt %. Above that concentration the tensile elongation at break increased; this was at the rate faster than the modulus decreased. The instantaneous and healing scratch depths and thus viscoelastic recovery were determined using a micro-scratch tester. The percentage recovery values are higher for the nanocomposites than for the pure epoxy.