Sustainable hybrid green nanofiller based on cellulose nanofiber for enhancing the properties of epoxy resin

Herein, a novel hybrid nano filler (CNF/cloisite 30B) for epoxy was designed and developed from cellulose nanofiber (CNF) and montmorillonite clay (cloisite 30B). The hybrid nanofiller has a morphology of exfoliated clay layers inside fibrous network of CNF as evident by transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies. The crystallinity index of hybrid nanofiller was calculated as 17% from Segal equation. Upon incorporation of hybrid nanofiller, thermal, mechanical and flame-retardant properties of the epoxy was simultaneously increased. A surge in the impact strength (101%) was observed for epoxy/0.5 hybrid nanocomposites. Fracture toughness of the epoxy increases with the addition of hybrid nanofiller, 0.5 phr loading shows the maximum fracture toughness value. Besides this, inclusion of hybrid nanofiller makes the fracture surface of epoxy rougher as confirmed by field emission scanning electron microscopy (FESEM). A significant improvement in the glass transition temperature (Tg) was observed for the fabricated epoxy/hybrid nanocomposites. Compared to pristine epoxy, about 16% and 10% improvement in Tg was observed for 0.5 phr and 1.0 phr CNF/cloisite30 B hybrid loading, respectively. Well-dispersed hybrid nanofiller in the epoxy matrix and the resulting filler matrix interaction restrict the chain mobility by forming several constrained regions in the nanocomposites, which in turn enhances the glass transition temperature of the hybrid nanocomposites. Hybrid nanocomposites exhibited remarkable flame retardancy due to the formation of thick char layer and the reduction in the total heat released (THR) was 34% and 20% compared to neat epoxy resin. The current work ensures that the developed hybrid green filler can be a potential, low cost, and eco-friendly reinforcing agent for polymers.