A weighting function approach to modeling the creep behavior of cellulose nanocrystal epoxy nanocomposites

Abstract This study investigates the influence of cellulose nanocrystals (CNCs) on the creep behavior and mechanical performance of epoxy-based nanocomposites, with a focus on optimizing CNC loading for enhanced durability. CNCs were extracted from cotton linters via acid hydrolysis and incorporated into an epoxy matrix (DGEBA-based KER 828) at varying weight percentages (0.5, 1.0, and 1.5 wt%) using a combination of mechanical and ultrasonic dispersion techniques. Tensile and creep tests were conducted on bulk epoxy to evaluate the mechanical and viscoelastic properties. Results indicate that 1.0 wt% CNC loading yields optimal dispersion, improving tensile strength by 20% and elastic modulus by 21% compared to neat epoxy, while also enhancing creep resistance by reducing the Norton-Bailey creep coefficient A by 14%. However, at 1.5 wt%, CNC agglomeration induces stress concentration, leading to reduced toughness and diminished creep performance. A modified Norton-Bailey model incorporating a CNC weighting function was developed to predict the creep behavior of nanocomposites, validated through experimental data with less than 10% error. The weighting function, derived from normalized creep rates, peaks at 0.987 wt% CNC, closely aligning with the experimentally determined optimum. These findings highlight the critical role of nanoparticle dispersion and interfacial adhesion in determining long-term performance, establishing 1.0 wt% CNC as the optimal threshold for sustainable, high-performance composites in structural applications.