Mechanical Properties and Electrical Conductivity of Poly(methyl methacrylate)/Multi-walled Carbon Nanotubes Composites

Carbon nanotubes (CNTs) remain one of the most efficient reinforcing material for enhanced mechanical and electrical properties. In this study, the effects of multi-walled CNTs (MWCNTs) fillers on mechanical, structural, and electrical properties of polymethyl methacrylate (PMMA)/MWCNTs composites were studied. The PMMA/MWCNTs composites, containing varying MWCNTs concentration of 0.1, 0.3, and 0.5 wt%, were prepared by a solution casting method. The mechanical properties of the composites such as tensile strength, elongation, Young modulus, tear resistance, fracture energy, impact strength, and hardness were investigated. Results showed that the mechanical properties of the composites were enhanced significantly. At 0.5 wt% MWCNTs, the tensile strength, elongation, tear strength, hardness, fracture energy and impact strength increased by 397%, 567%, 89%, 27%, 12%, and 36%, respectively, while the Young modulus decreased by 26% compared to pure PMMA polymer sample. Both the dc electrical conductivity and the activation energy increased with increased concentration of MWCNTs. From the electrical conductivity measurements, the percolation threshold was found to equal similar to 0.55 wt% MWCNTs. Based on the Fourier-transform infrared spectroscopy analysis, enhancement of mechanical and electrical properties is attributed to the formation of covalent bonds between polymer strands and MWCNTs. Moreover, a mechanism was proposed to describe the influence of MWCNTs on electrical and mechanical properties of PMMA/MWCNTs composites.