Exploring the suitability of psyllium husk nano-ash as green nano-filler for development of natural rubber nanocomposite

For the first time, an agricultural waste-based nanomaterial, psyllium husk nano-ash (PHNA) was applied as an environmentally friendly, cost-effective and naturally occurring green nano-filler for the development of natural rubber (NR) nanocomposite. Fourier transformed infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) were performed to characterise the psyllium husk-based PHNA. The cure properties including rheometric torque difference (R_∞) and curing rate index (CRI) were found to increase due to the addition of only 3 parts per hundred parts of rubber (phr) of PHNA into the NR matrix. The mechanical properties like moduli at 100% and 300% elongation, tensile strength (TS), percentage of elongation at break (%EB) and elasticity of the NR composites were found to be improved in the presence of the 3 phr of the PHNA. The dispersion of the PHNA particles in the rubber matrix was confirmed by the FESEM analysis. The NR-PHNA compatibility was studied by the conformational entropy change (∆S) and the elastic Gibbs free energy change (∆G). Thermal stability of the NR composite was also enhanced due to incorporation of the PHNA and this was confirmed by oxidative thermal ageing experiment and thermo-gravimetric analysis (TGA).