Preparation and Characterization of High-Performance Natural Rubber Latex Composites with Sodium Methylene Bis-naphthalene Sulfonate Modified Multiwalled Carbon Nanotubes

Multiwalled carbon nanotube (MWCNT) are widely used as reinforcing fillers for rubber materials due to their excellent mechanical, thermal and electrical properties. However, the MWCNT dispersion in the rubber matrix is normally poor owing to their high aspect ratio and agglomeration characteristics. In this paper we describe our research on natural rubber latex (NRL) composites filled with noncovalent modified multiwalled carbon nanotube (MWCNT), prepared by sodium methylene bis-naphthalene sulfonate (NNO) as an anionic surfactant. The high-performance NRL/NNO/MWCNT composites were prepared by a liquid latex blending method. Transmission electron microscopy (TEM) showed the dispersion of MWCNT modified by NNO in water was significantly improved. The original MWCNT dispersion state in the water was not sufficient, with a range of small to big agglomerates. On the other hand, the entangled bundles of NNO/MWCNT were reduced in size or eliminated. The NNO's interface interaction with the MWCNT was further studied by Raman spectroscopy and thermogravimetric analysis (TGA) which indicated the NNO was capable of modifying the surface of the MWCNT. In addition, the effects of the modified MWCNT on the mechanical and dynamic mechanical properties of rubber composites were also characterized. NNO was absorbed on the surfaces of the MWCNT through noncovalent action, which enabled the MWCNT to more evenly disperse in the rubber matrix, forming a good filler structure in the NRL and improving their composites mechanical properties. We note our approach is an easy and eco-friendly method to enhance the NRL composites.