Improved mechanical properties without compromises in the processability

Fracture toughness and impact resistance of epoxy resins can be improved significantly by reinforcing them with nanoparticles. Further mechanical and thermal properties can be improved with Nanopox® G. Due to the nanoparticles in Nanopox® G, low viscous systems despite high filling ratios can be obtained.

Product overview
Improvements to properties
How it works

Product overview [back]

Technical data (no specification)

Improvements to properties [back]

Under the brand name Nanopox® G we are producing a number of colloidal silica sols in various epoxy resins which are highly suitable for modifying epoxy resins. Important properties can be significantly improved in epoxy formulations by using Nanopox® G:

• lower viscosity of the formulation in comparison to conventional reinforced fillers
• no sedimentation
• increase in fracture toughness, impact resistance and modulus
• improved scratch and abrasion resistance
• reduction of shrinkage and thermal expansion
• improvement, or at least no negative effect, in numerous desired properties, such as: thermal stability, chemical resistance, glass transition temperature, weathering resistance, dielectric properties
• the combination of Nanopox® G  with conventional fillers - such as quartz - enables a reduction in the resin content of the formulation, which means that the total filler content can be increased to previously unattained levels
• the processability remains essentially unchanged in comparison to the respective base resin

Figure 1 shows the improvement of the fracture toughness (KIC) and the modulus as a function of the silica content. The system shown is based on Nanopox® G 420 cured with anhydride. A significant increase in the fracture toughness is discernible with an accompanying increase in the modulus.
 
Nanopox® G is used in applications where the above improvements to properties are desired or necessary, without compromising the processability by an excessive increase in viscosity (known when using fumed silica). Example applications are casting compounds and coatings .

Figure 1:  Development of fracture toughness and modulus with increasing nanosilica content

How it works [back]

Nanopox® G is a colloidal silica sol in a matrix of a standard epoxy resin. The disperse phase consists of surface-modified, spherically shaped silica nanoparticles with diameters below 50 nm and an extremely narrow particle size distribution (Fig. 2). 

Figure 2:  Particle size distribution (Determined by SANS)

The silica spheres, only a few nanometers in size, are distributed agglomerate-free in the resin matrix (Fig. 3). This produces a very low viscosity of the dispersion with silica contents of up to 40 wt%.

Figure 3: TEM – images of a cured Nanopox® sample with 5% SiO2 nanopartcles

The nanoparticles are chemically synthesized from aqueous sodium silicate solution. In this unique process the binding agent is not damaged, in contrast to processes in which powdered fillers are dispersed with dissolvers or other equipment using high shear energy.

For further details, please contact our application specialists.