Enhancing dynamic viscoelastic performance of flax fiber/fly ash hollow cenosphere‐reinforced composites coated by in situ fabrication of ultrasonically synthesized nanotitanium dioxide

Abstract

AbstractThis study demonstrates a novel, single‐step, and low‐energy ultrasonic approach to fabricate lightweight, high‐performance flax fiber‐reinforced composites enhanced by nanotitanium dioxide coating and fly ash hollow cenospheres. This innovative approach leads to a remarkable 23% weight reduction compared with conventional composites, making it ideal for the applications demanding both lightweight and superior mechanical properties. Through dynamic mechanical testing, it is found that the composites' viscoelastic behavior, including storage modulus and damping factor, is significantly influenced by both frequency and temperature. By applying time–temperature superposition principles, the composite's dynamic properties are comprehensively characterized across a wider frequency range. A modified fractional calculus Huet–Sayegh model accurately captures the observed viscoelastic behavior. The combined effect of nanotitanium dioxide coating, which strengthens the fiber–matrix interface, and the inclusion of rigid fly ash hollow cenospheres results in significant improvements in both storage modulus (10% increase at room temperature) and peak loss factor (80% increase) compared with uncoated flax fiber‐reinforced composites. The nanocoating and cenospheres' rigid shells contribute to enhanced stiffness, while the cenospheres' hollow structure provides efficient energy dissipation mechanisms, leading to an improved damping performance. This ultrasonic approach offers a promising and sustainable method for synthesizing natural fiber nanocomposites with superior viscoelastic properties.