Epoxy/nano‐silica composites: Curing kinetics, glass transition temperatures, dielectric, and thermal–mechanical performances

Abstract

Nano-silica particles were employed for enhancement of epoxy vacuum pressure impregnating (V.P.I.) resin. The influences of nano-silica particles on the curing reaction, glass transition temperatures, dielectric behavior, and thermomechanical performances were investigated. The activation energy (E) for the epoxy curing reaction was calculated according to Kissinger, Ozawa, and Friedman-Reich-Lev methods. The glass transition temperatures were determined by means of differential scanning calorimetry, dynamic mechanical analysis, dc conduction, and ac dielectric loss analysis. Relationships between the glass transformation behaviors, the thermomechanical performances, and the dielectric behaviors were discussed. The influences of nano-silica particles on the mechanical properties were also discussed in terms of non-notched charpy impact strength and flexural strength. The morphologies were studied by means of SEM and TEM. The results indicated that nano-silica particles could effectively increase both the toughness and strength of epoxy resin at low loadings (no more than 3 wt %) when nano-silica particles could be well dispersed in epoxy matrix without any great aggregations.

Synergistic Effects of Mixed Silica Micro-nanoparticles on Compressive Dynamic Stiffness and Damping of Epoxy Adhesive

“…Pure nanoparticles at 2 wt% silica are well dispersed, achieving a large effective interface area; therefore, these provide stronger stiffening effects than those of micro-nanoparticles. Good dispersion of low-content silica nanoparticles was observed, which is in agreement with previous works by Bondioli et al [10], Zheng et al [9], and Feli and Jalilian [8]. This result suggests that composing silica micro and nanoparticles in appropriate ratios improves their dispersion up to certain weight fraction when using only a conventional mechanical mixer.…”

“…Welldispersed silica nanoparticles stiffen and toughen an epoxy adhesive more efficiently than silica microparticles owing to their larger surface-to-volume ratio, forming a more substantial matrix-filler interface area at a given weight fraction [1][2][3][4][5][6][7]. However, without any treatment, high-silica-content nanoparticles are difficult to disperse uniformly using a conventional mechanical mixer and tend to aggregate/agglomerate in the epoxy matrix [8][9][10].…”

On depression of glass transition temperature of epoxy nanocomposites

“…In recent years, many researchers have paid great attention to modifying the physico-mechanical properties of epoxy resins using inorganic nanoparticles. Provided the nanoparticles are evenly dispersed in epoxy matrices without serious agglomerations, several basic mechanical properties including stiffness, failure strength, fracture toughness of epoxy resins as well as interlaminar fracture resistance of epoxy-based laminate composites are increased effectively [1][2][3][4][5][6][7][8][9][10]. However, it is still uncertain how nanoparticles affect the glass transition behaviors of epoxy resins.…”

Preparation and Properties of Wood Flour Reinforced Lignin-Epoxy Resin Composite

“…These properties help epoxy resin to meet the performance requirements of some demanding applications. These applications include areas as diverse as construction, electronics, adhesives, and coatings (Musto et al 2007;Zheng et al 2009;Saad et al 2011). In epoxy cross-linked polymers, additive agents, such as the curing agent and the filler, play decisive roles in its properties.…”