ACAV A2

Surface chemistry
Surface chemistry determines rheology of coating colors in low shear rate area (rotational viscometers).

There are both attractive and repulsive forces between the particles.
The main forces are:
- Electric attraction/repulsion
- Van der Waals attraction
- Steric repulsion

If attractive forces are too strong, particles tend to flocculate. Viscosity increases and suspension becomes unstable. Other very important factor is reactions between polymer chains and pigment/latex particles. In low shear area clay coating colors have usually higher viscosity than calcium carbonate coating colors. For example CMC and clay form strong structures.

The same applies to viscoelasticity. CMC and clay tend to form structures stronger than starch or carbonate. Surface chemistry and structure formation are not so important at higher shear rates, as structures break down under the shear.

»ACAV A2
»Full Shear Rates
»Surface Chemistry
»Hydrodynamic Factors
»Key Benefits

»ACAV A4
»Key Benefits

»SLIT System

»DRW

»PERMI
»Key Benefits