Molecular Dynamics Investigation on the Effect of MWCNTs on Thermo-Mechanical Properties of Amorphous Cellulose Reinforced with Silicon Carbide Nanotubes

Abstract

Cellulose is a biopolymer frequently implemented as fibers and membranes to fabricate high-performance and multi-functional composites. In this study, the molecular dynamics simulation is used to investigate the effect of CNTs on elastic modulus, ultimate strength, and toughness properties of silicon carbide nanotubes (SiCNTs) reinforced cellulose nanocomposite. Based on the simulation results, the temperature of the surrounding environment controls the stress transfer at the nanotube-cellulose interface. As the cellulose expands with increasing temperature creating more void regions at the filler-matrix interface, the load transfer from cellulose to nanotubes is reduced, leading to a noticeable reduction in tensile properties of cellulose composite. This behavior critically affects the tensile strength of cellulose composite reinforced with multi-walled CNTs (MWCNTs). The single-walled CNT with a high aspect ratio increases the cellulose composite’s tensile strength and toughness, while the MWCNT introduces the most significant increase in cellulose stiffness. The difference in polarity between MWCNT and cellulose, along with the low aspect ratio of the external nanotube, would limit the capability of MWCNT in improving the tensile strength and toughness of cellulose. The single-walled SiCNTs are structurally unstable, and their stiffness degrades rapidly at high temperatures. Therefore, they are hybridized with CNTs to improve their stiffness and structural stability. SiCNT, which is hybridized with two CNTs, exhibits the best structural performance at 100, 300, and 500 K temperatures.