Preparation And Properties Of Epoxy/SiO₂ Hollow Spheres Nanocomposites

As a good thermosetting resin, Epoxy resin (EP) has been widely applied in printed circuit board and used as casting material of electronic apparatus. Epoxy resin needs to be further developed because of the development of large scale integrated circuit, electric products constantly changed to miniaturization, high frequency and high powerful.In this paper, nano-structured SiO₂ hollow spheres with particle size of 50nm were successfully synthesized from tetraethyl orthosilicate (TEOS) by the template approach with the ultrasonic assisted. Then, with adding the nano-structured SiO₂ hollow spheres, toughening reagent and curing agent into the epoxy resin, the EP/SiO₂ hollow spheres nanocomposites were prepared by mechanical blend method. The chemical structure, fractured surface morphology, decomposition temperature (Td) and dielectric properties of the nanocomposites were characterized by Fourier Transform Infrared Spectrometer (FT-IR), Scanning Electronic Microscope (SEM), Thermogravi- metric analysis(TGA), Precision impedance analyzer, respectively.The results indicate that: For EP/SiO₂ and EP/PU/SiO₂ hollow spheres nanocomposite materials, dielectric constant (ε) both decreased with frequency increasing at the same contents of SiO₂; When the content of SiO₂ hollow spheres is more than 3wt%,εalso decreased with increasing contents of SiO₂ at the same frequency.For EP/SiO₂ hollow spheres nanocomposites, dielectric loss (tanδ) increased with increasing of frequency. Tanδof nanocomposites was larger than pure EP from102 to 104Hz, but less from 104 to 106Hz. With adding the polyurethane into the materials, the values of tanδof all the samples decreased with increasing of frequency gradually in the range of 102¹03.5Hz, but increased in the range of 10^3.510⁵Hz. At the same frequencies, the values of tanδincreased with increasing contents of SiO₂ in the range of 10²¹0^3.5Hz, but decreased in the range of 10^3.510⁵Hz.With polyurethane modified, the impact performance of composite materials was first increases, then decreases with the content of polyurethane increasing. When polyurethane content is 15wt%, impact performance (17.5kJ/m²) and tensile strength (53MPa) both reached the maximum, and they increase by 37.8% and 39.6%. Meanwhile, with adding the polyurethane into the materials, the thermal property was slightly improved from the TGA curves.