Effects of carbon nanotube content on the mechanical and electrical properties of epoxy-based composites

The effects of multi-wall carbon nanotube (MWCNT) content on the mechanical and electrical properties of MWCNT/epoxy composites were investigated. Results indicate that both tensile strength and flexural modulus exhibit maxima at MWCNT contents of 0.1% and 0.25% (mass fraction), respectively. The tensile modulus increases and the strain to failuredecreases with MWCNT content, indicating a transition from plastic to brittle failure with increasing MWCNT content. The flexural strength of a sample with a MWCNT content of 0.05% is the highest. The electrical percolation threshold of the composite is found to occur at a 0.5% MWCNT addition. A good dispersion of MWCNTs in epoxy is important to improve the mechanical properties of the composites. A non-uniform dispersion leads to agglomeration of MWCNTs, which causes an early-stage failure under loading. The electrical properties of the composites are less affected by the presence of agglomerates.