Effect of surface treatment of MWCNTs on the enhancement of the thermal and mechanical properties of aramid-MWCNT composites

Abstract

Visco-elastic properties in thermo-set composites can be enhanced using an Aramid matrix reinforced with multi-walled carbon nanotubes (MWCNTs). Surface modifications of MWCNTs, with silane coupling agents, improve their thermal and mechanical properties. The objective of this study is to evaluate Aramid-MWCNT nanocomposites modified with propyl silane (APrTES) and aromatic silane (APhTMS) by comparing their mechanical and thermal enhancements. Two types of composites were prepared: physically mixed with pristine MWCNTs (Ar-MWCNT) and chemically bonded with surface-modified MWCNTs (Ar-PrSi-MWCNT and Ar-PhSi-MWCNT). The mechanical and thermal stability of the composites was assessed using dynamic thermal mechanical analysis (DMTA) and thermogravimetric analysis (TGA). The chemically bonded Ar-PrSi-MWCNT composites demonstrated a 28% increase in tensile strength and a 15% improvement in storage modulus compared to the physically mixed composites. Glass transition temperature (Tg) increased by 10 °C, indicating enhanced thermal stability. The phenyl silane-modified composites (Ar-PhSi-MWCNT) exhibited the highest storage modulus (5.50 GPa) and Tg (370 °C), with a 28% increase in tensile strength. TGA results showed a decomposition temperature of 524 °C, confirming superior thermal stability. These improvements are attributed to the better dispersion of silanized MWCNTs and stronger interfacial bonding between MWCNTs and the Aramid matrix. The phenyl group in the silane modification contributes to a rigid interface, providing higher performance. Overall, surface modification with APrTES and APhTMS significantly enhances the thermal and mechanical properties of Aramid-MWCNT nanocomposites, with the phenyl silane-modified systems outperforming the propyl silane-modified and physically mixed systems.