Mechanism and characterization of polydopamine modified multi-walled carbon nanotubes reinforcement of natural rubber latex composites

Abstract Multi-walled carbon nanotubes (MWCNTs) are generally applied to reinforce macromolecular material due to their low density, high thermal conductivity, and high elastic modulus. However, the reinforcement effect of MWCNTs is not significant due to their poor dispersion. In this paper, we modified MWCNTs by using polydopamine (PDA). We found this is the best way to improve the dispersity of MWCNTs. We characterized the π-π conjugation reaction between MWCNTs and polydopamine by TGA, FTIR, and Raman spectroscopy. The results indicated the physical adsorption of PDA did not change the structure of MWCNTs. Besides, we also tested the mechanical properties of PDA modified MWCNTs reinforcement of Natural Rubber Latex Composites (PDA/MWCNTs/NRL). We found that when the mass ratio of MWCNTs to PDA was 1:0.3, the tensile strength and tear strength of PDA/MWCNTs/NRL composites increased by 25% and 53%, respectively. These results indicated that the surface modification of PDA improved the dispersion of MWCNTs in PDA/MWCNTs/NRL. In addition, combined with the test results and the sliding theory of the rubber macromolecular chain, we first proposed the reinforcement mechanism of MWCNTs in natural rubber matrix composites and described it in detail through pictures.