Himalayan nettle fibre-reinforced polymer composite: a physical, mechanical, and thermal analysis

Himalayan nettle fibre is abundantly available in the Himalayan regions of India and can effectively replace synthetic fibre in epoxy-based polymer composite synthesis. Fibre from nettle plants can be extracted by water, dew, controlled microbial retting, enzymatic treatment, and mechanical decortication methods. Cellulose (>86 wt.%) is the principal constituent of this fibre. In this study, epoxy-based composites were prepared with 0, 15, 20, 23, 25, 27, and 30 wt.% fibre loadings and investigated the influence of fibre content on thermal, mechanical, and physical properties. The samples were analysed with X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, universal testing machine, dynamic mechanical analysis, thermogravimetric analysis, density and void fraction measurement, and water absorption test. It was found that mechanical and thermal properties were increased with the increase in fibre loadings, attaining the maximum values at 23 wt.%, which signified the improvement in mechanical and thermal properties with fibre reinforcement. The fibre fraction of 23 wt.% resulted in the higher tensile (57.69 MPa), flexural (98.60 MPa), impact (0.689 J) strength, better thermal stability, higher storage modulus (1390.90 MPa), loss modulus (413.05 MPa), and crystallinity (40.5%). This study concludes 23 wt.% fibre loading as optimum reinforcement for the studied epoxy polymer.