Interfacial engineering and thermomechanical enhancement of bio-based grewia optiva fiber/PALF/marble dust reinforced-reinforced epoxy composites for circular economy applications

The rapid population growth and escalating environmental concerns have heightened the need for sustainable materials with enhanced mechanical properties that meet current structural requirements. This study aimed to systematically characterize the thermomechanical properties and interfacial bonding of surface-modified Grewia Optiva (Bhimal) fiber and pineapple leaf fiber (PALF)-based composite materials to evaluate its potential as a sustainable structural material. Bhimal fibers sourced from the Dehradun region of Uttarakhand India were used for reinforcement and PALF was introduced as a secondary natural-fiber reinforcement epoxy resin as a matrix, and marble dust as filler, which improve mechanical and physical properties. Surface modification with alkaline (NaOH) treatment, followed by benzoyl peroxide initiation, was used to improve fiber-matrix interfacial adhesion. Dynamic Mechanical Analysis (DMA) study showed an increased storage modulus (up to 16.14 GPa), a reduction in damping factor (tan δ), and improved glass transition-related parameters (Tg), suggesting improved interfacial stress transmission and increased crosslink density. Thermogravimetry Analysis (TGA) suggests thermal stability up to 290 °C, and Scanning Electron Microscopy (SEM) analysis images of the shattered surfaces show that the fiber and matrix are well bonded. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the chemical modification induced by surface treatments. The impact strength of the Bhimal fiber-based composite material was improved by 305%. This work helps to determine the value of Grewia Optiva (Bhimal) fiber-based composite and increases the understanding of interfacial Grewia Optiva structural composites.