(2) Modification of epoxy resin composite materials

Epoxy resin has good mechanical, electrical, adhesive, and chemical stability properties, making it an important application in adhesives, electrical insulation materials, and composite materials. However, the biggest weakness of epoxy resin is the brittleness of the cured product. Traditional toughening methods can increase the strength of the material by several times, but inevitably reduce other properties of the material. The rise of nanotechnology has ushered in a new revolution in the modification of this material. Adding nano-SiO2 to epoxy resin is completely different from the epoxy resin-based composite material added with coarse-crystalline SiO2 in structure. Coarse-crystalline SiO2 is generally added as a reinforcing agent and is mainly distributed between the chains of polymer materials. Nano-SiO2 has strong activity due to its serious surface coordination deficiency, huge specific surface area and surface oxygen deficiency. It can easily form a bond with the oxygen of epoxy cyclic molecules, thereby increasing the bond force between molecules. At the same time, some nano-SiO2 particles are still distributed in the gaps of the polymer chain. Compared with coarse-crystalline SiO2, they show high fluidity, thereby greatly improving the strength, toughness and ductility of the epoxy resin material added with nano-SiO2.