Effect of organosilane coupling agents on microstructure and properties of nanosilica/epoxy composites

Abstract

Three types of silane coupling agents, γ‐aminopropyltriethoxysilane, γ‐glycidoxypropyltrimethoxysilane, and γ‐methacryloxypropyltrimethoxysilane, were used as modifiers to modify the surface of the nanosilica, respectively, and the nanocomposites of the epoxy resin filled with nano‐sized silica modified by three silane coupling agents were prepared by physical blending. The properties of the modified silica nanoparticles were characterized by Fourier transform infrared spectrum and particle‐size analyzer. The microstructure, mechanical behavior, and heat resistant properties of the nanocomposites were investigated by transmission electron microscopy, scanning electron microscopy, thermo gravimetric analyses, differential thermal gravity, differential scanning calorimetry, and flexural tests. The results showed that these modifiers are combined to the surfaces of nanosilica by the covalent bonds, and they change the surface properties of nanosilica. The different structures of coupling agents have different effects on the dispersibility and stability of modified particles in the epoxy matrix. In comparison, the silica nanoparticles modified by γ‐glycidoxypropyltrimethoxysilane exhibit a good dispersivity. The nanocomposites with 4 wt% weight fraction nanosilica modified by γ‐glycidoxypropyltrimethoxysilane have higher thermal decomposing temperature and glass transition temperature than those of the other two composites with the same nanosilica contents, and they are raised by 43.8 and 8°C relative to the unmodified composites, respectively. The modified silica nanoparticles have good reinforcing and toughening effect on the epoxy matrix. The ultimate flexural strengths of the composites with 4 wt% nanoparticles modified by γ‐aminopropyltriethoxysilane, γ‐glycidoxypropyltrimethoxysilane, and γ‐methacryloxypropyltrimethoxysilane are increased by 10, 30, and 8% relative to the unmodified composites, respectively. The flexural fracture surfaces of modified composites present ductile fracture features. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers

Organosilanes Surface Modification of Zirconium Diboride Composite Engineering Ceramics and Its Effect on the Tribological Performance of Epoxy Composites

“…Meanwhile, the O-H stretching peaks at 3 440 cm À1 clearly broaden, and the intensity of O-H bending peaks at 1 380 cm À1 increases, which demonstrates that the amounts of -OH groups on the surface of modified particles increase. [25] These results mentioned above indicate that ZrB 2 /Al 2 O 3 composite ceramic particles were successfully functionalized with functional groups of organosilanes introduced on the surface of composite particles by the chemical reaction between silane compounds and composite particles and the chemical bonding of organosilane onto composite particles surfaces was realized through Al-O-Si bonds. Also the absorption peaks at around 2 928 and 2 856 cm À1 which are ascribed to asymmetrical and [24] in Figure 1b-d, respectively.…”

“…[22] In comparison with Figure 1a, after surface modification by three types of organosilanes, the IR spectra of modified particles as presented in Figure 1b-d show new absorption bands. This is mainly caused by the partial overlap of the absorption peaks of -NH 2 introduced by g-aminopropyltriethoxysilane (N-H, 3 434 cm À1 ) [25] and -OH. Meanwhile, the O-H stretching peaks at 3 440 cm À1 clearly broaden, and the intensity of O-H bending peaks at 1 380 cm À1 increases, which demonstrates that the amounts of -OH groups on the surface of modified particles increase.…”

Fabrication and evaluation of acrylated epoxidized castor oil‐toughened diglycidyl ether of bisphenol A nanocomposites

“…[42,43] 100 g of castor oil (CO), 26 g of glacial acetic acid, and 29 g of H 2 SO 4 were charged in a three-necked round flask.…”

Preparation of water‐soluble electrical steel coating with SiO2 modified by glycine

“…The compatibility between water-soluble resin and nano-particle was a problem [1][2][3][4][5] for the water-based composite electrical steel coating. So it is a great chance to deal the problem, as a result the nano-particles were always modified to enhance the compatibility [6][7][8][9][10][11][12], such as modified by silance coupling agent [13,14], titanate coupling agent, or grafted by polymer [4,[15][16][17][18][19]. In the present paper, glycine was used to graft the SiO 2 nano-particles in the study, and the compatibility between the polyester solvent and the SiO 2 particles was enhanced.…”