243 / 2018-09-24 16:12:13

Thermal Stability of Epoxy Resin Doped by Aminosilane Coupling Agents with Different Chain Lengths

Molecular dynamics; Silane coupling agents; Epoxy resin; Thermal properties

In this work, based on molecular dynamics method to study microscopic mechanism of polymer composites, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 3-[2-(2-aminoethylamino)ethylamino]-propyl-trimethoxysilane with different chain lengths were grafted on the surface of nano-silica particles, respectively. Then, the surface-modified nanoparticles were doped into the epoxy resin, and influence of the doped nano-silica particles on the thermal performance of the epoxy resin was studied. Firstly, the surface of nano-silica particles was treated by hydrogenation, that is, adding hydrogen atoms to unsaturated oxygen atoms and hydroxyl groups to unsaturated silicon atoms on the surface of nano-particles of dioxide, and then three silane coupling agents were grafted onto the surface of nano-silica particles. Secondly, the grafted nanoparticles were doped into epoxy resin matrix, and the structure of the model was optimized based on COMPASS force field so as to obtain a reasonable structure model. Lastly, the parameters such as radial distribution function, mean square displacement, glass transition temperature and thermal conductivity of the composites were obtained. The results show that the glass transition temperature of the epoxy resin that were doped by nanoparticles which surface had been grafted with 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 3-[2-(2-aminoethylamino)ethylamino]-propyl-trimethoxysilane increased by 16.5 K, 36.5 K and 21.5 K, and also the thermal conductivity elevated by 4.9%, 24.5% and 3.2% compared to pure epoxy, respectively. The results show that the nano-silica particle composites doped with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane have better thermal properties than others under the same conditions.