Evonik is the leading manufacturer of surface modified silica nanoparticles in epoxy resins. Using nanosilica several important properties of fiber reinforced composites can be improved:
- significantly improved modulus and
- flexural strength
- drastically improved fatigue performance
- increased toughness
- improved surface quality (reduced print
- reduced microcrack formation
The nanoparticles are chemically synthesized from aqueous sodium silicate solution. In this unique process the epoxy matrix resin is not altered, in contrast to processes in which powdered fillers are dispersed with dissolvers or other equipment using high shear energy.
These products are concentrates and, for most composite applications, are diluted with standard epoxy resins. Typical nanosilica levels in e.g. VARTM resin systems are 10 %.
products are suitable for all hardeners and all manufacturing processes. As the silica nanoparticles do not sediment, even solvent-based prepregging does not pose a problem.
Due to their small size and the absence of any larger aggregates, the nanoparticles can easily penetrate all fiber structures without compromising the impregnation by excessive viscosity, thereby enabling all the state-of-the-art process technologies like resin infusion, RTM, or resin injection. In addition to significantly improved mechanical properties (modulus, fracture toughness), the thermal expansion, shrinkage and electrical properties can also be improved.