Interaction of fumed silica with epoxy resin
Researchers recently investigated the chemical interaction of fumed silica of different sizes with epoxy via ultrasonication for improved coating.
Blank epoxy coating (EC) and fumed silica epoxy composite coatings (SECCs) reinforced with different loading levels of nano- (7 nm) and micro (0.2-0.3 μm) silica were successfully prepared using ultrasonic technique. SEM analysis revealed a uniform dispersion of nano- and micro-silica fillers in the epoxy matrix up to 3 wt.% loading. It is found that ultrasonication results in permanent chemical bonding between epoxy resin and silica particles as investigated by FT-IR spectroscopy and DSC. Quantitative FTIR generally reveals that nano-silica shows more participation in chemical bonding to epoxy than micro-silica.
Use of nano-silica leads to improved corrosion resistance
Coated steel panels with either EC or SECCs were evaluated with regard to surface wettability, corrosion resistance, thermal stability and mechanical properties. Micro-silica treated coatings show enhanced hydrophobicity in contrast to nano-silica samples as revealed by contact angle measurements. Results of salt spray test and thermogravimetric analysis indicate that the addition of nano-silica show improved corrosion resistance and thermal stability of the epoxy coating compared to micro-silica. The mechanical properties namely scratch hardness, adhesion, impact strength and abrasion resistance were also improved in the same manner.
The study is published in: Progress in Organic Coatings Volume 129, April 2019, Pages 1-9.
