The effects of octadecylamine functionalized multi-wall carbon nanotubes on the conductive and mechanical properties of ultra-high molecular weight polyethylene

Multi-wall carbon nanotubes (MWCNTs) are usually used as conductive fillers to improve the conductive and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) simultaneously. But the poor dispersion of MWCNTs in UHMWPE and the weak compatibility between MWCNTs and UHMWPE lead to lots of defect sites and limit the efficiency of load transfer between UHMWPE and MWCNTs. To solve these problems, octadecylamine (ODA) functionalized MWCNTs (MWCNT-ODA) were prepared and its effects on the conductive and mechanical properties of UHMWPE were investigated. The X-ray photoelectron spectrometer (XPS) measurements indicated that ODA was successfully grafted on the surface of MWCNTs. The electrical conductivity tests showed that 0.5 wt% addition of MWCNT-ODA can obviously reduce the volume resistivity of UHMWPE composites by 12 orders of magnitude compared to pure UHMWPE. Meanwhile, its impact strength achieved an increase of about 42.1% and the tensile strength was slightly improved from 33.5 MPa to 40.7 MPa compared with that of UHMWPE. The microstructure features of the impact fracture surfaces were analyzed by field emission scanning electron microscope (SEM). This result revealed the existence of a stronger interfacial force between the UHMWPE and MWCNT-ODA, which is responsible for the improvement of mechanical properties of UHMWPE.