The Surface Modification Of Nanoparticles And Its Phenolic Coatings

Nano-particles have high surface activity and a great inclination to agglomerate due to the lack of coordinate atoms on the surfaces. Moreover, the poor interfacial compatibility between the nano-particles and the polymer matrix prevents the formed nano-composite from obtaining the expected excellent properties. As a result, dispersion of nano-particles plays a crucial role in preparing high-performance nano-composites. In this paper, three different methods were applied to modify nano SiO₂: coupling agent grafting method, phenolic resin grafting method with salicylic acid as the medium, and polyethylene glycol grafting method. Fourier transform infrared spectroscopy (FT-IR) characterization and thermal gravimetric analysis (TGA) revealed the chemical linkage between nano-silica and the grafted organic matter. Besides, it was found phenolic resin grafting method with salicylic acid as the medium can obtain the best grafted ratio, that was 34.52%. From transmission electron microscopy (TEM) images it can be observed that the modified nano-particles were well dispersed. Nano compound coating was prepared by adding modified nano silica into phenolic coating. The cohesion, hardness, wear property and resistance to NaCl, acid, alkali and water of the phenolic coating was estimated by relevant assessment methods. The result showed all of these properties were improved to some extend. It was also found that the properties of composite coating changed with the variation of filling ratio, the preferred modification methods and the preferred filling ratio of every kind particles were educed by comparing different kinds of properties.