Facile coating of carbon nanotubes by different resins for enhancing mechanical, electrical properties and adhesion strength of NR/Nylon 66 systems

In this work, the effect of multi-walled carbon nanotubes (MWCNTs) coated by two resins, namely unsaturated polyester (R1) and urethane alkyd resin (R2) on mechanical, electrical, wear properties, and adhesion strength of natural rubber (NR)/nylon 66 systems before and after UV exposure was studied. Three different loadings of CNTs (i.e. 0.5, 1.5, and 3 wt.%) were used and characterized by X-ray diffraction. Transmission electron microscopy images of coated CNTs nanocomposites confirmed that better dispersion of nanofiller in the NR matrix occurred at 1.5 wt.%. The results revealed that the use of 1.5 wt.% CNTs coated by R1 resin increased the tensile strength by 340% compared to unfilled NR. Also, the electrical behavior and the wear resistance of NR nanocomposites were enhanced. Pull-out adhesion tests clarified that the adhesion force of NR/R1-1.5% was nearly twice that of the pristine NR and showed the best adhesion, especially for unexposed samples. While for exposed samples, the results showed inferior adhesion values in most matrices. Scanning electron microscopy utilized to demonstrate the failure mechanism of adhesion for investigated samples between the rubber and nylon 66 cords after pull-out tests.