NANOPOX® products are high-performance concentrates of nanosilica in epoxy resins and have been especially designed for adhesive applications. The silica phase consists of surface-modified SiO2 nanospheres with a defined size of 20 nm and a very narrow particle-size distribution. NANOPOX® products are used to replace part of the epoxy resin in an existing formulation; typically in the range of 8–15%. Some applications require higher concentrations of nanosilica. They can be blended with all commercial epoxy resins and cured with all commercial hardeners available. The introduction of nanosilica in the epoxy formulation improves various properties of the adhesive:- increased strength, modulus, and hardness
- improved toughness (fracture energy, fracture toughness, impact resistance)
- significantly improved fatigue performance
- dramatically improved compressive properties
- no change in Tg
As the particles are entirely transparent, NANOPOX® products can be used for transparent adhesives as well. NANOPOX® A 611 can be used to formulate UV-curable adhesives. Application Recommendations: Part of the epoxy resin used in the formulation to be improved is replaced by a NANOPOX® A product. The amount of hardener is reduced in proportion to the new epoxy equivalent of the resin blend. For some non-stochiometric hardeners like dicyandiamide, you need not change the hardener amount. Use fillers and other ingredients of the formulation as you normally would. If the viscosity of NANOPOX® products turns out to be too high for the formulating procedure, manufacturer recommends preheating the product to 60–80°C. The viscosity will be lowered below 10,000 mPas. The best improvements in adhesive properties can usually be obtained with around 5 wt% silica nanoparticles. Information provided by Evonik |
