Effects of multi-walled carbon nanotubes on the physical and mechanical properties of high-density polyethylene/wood flour nanocomposites

In this study, the effect of multi-walled carbon nanotubes (MWCNTs) and maleic anhydride-grafted polyethylene (MAPE) on the physical and mechanical properties of composites based on wood flour (WF) and high-density polyethylene (HDPE) was investigated. To meet this objective, MWCNTs, as a reinforcing agent, in 4 levels of 0, 1, 3, and 5 wt% and MAPE, as a compatibilizer, in 2 levels of 0 and 3 wt% were used. The amount of WF was fixed at 50 wt% for all formulations. First, the materials were prepared by melt compounding process in an internal mixer (Brabender® Plasti-Corder®), and then the samples were manufactured by injection molding method. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results showed that when the contents of the MWCNTs were increased from 0 to 3 wt%, the tensile strength and modulus of the samples increased to 41.7% and 24.3%, respectively, and the water absorption values of the samples decreased to 58.8%. Similar results were also observed for the thickness swelling values. Both mechanical and physical properties of samples were improved by adding MAPE up to 3 wt%. The nanocomposites having 3 wt% MWCNTs and 3 wt% MAPE exhibited the highest impact and tensile strength values, while tensile modulus and physical properties reached their maximum when 5 wt% of MWCNT and 3 wt% of MAPE were used. Also, SEM micrographs showed that CNTs can fill the voids of wood–plastic composites, and the addition of MAPE and MWCNTs enhanced the interaction between the components.