Corona treatment – when atmospheric air is subjected to different voltage potentials, an electrical discharge develops leading to an avalanche effect caused by a collision of neutral molecules and the electrically charged molecules that constitute the voltage.
At the collision, the neutral molecules are electrically charged, resulting in a heavily loaded zone or “lightning”. This in turn creates a powerful oxide blend of ozone and nitrogen oxides. To avoid this avalanche effect, an isolator is placed between two electrodes.
The result is a cloud of ionized air or corona discharge used for surface treatment of plastic and other materials. When a substance is placed under the corona discharge, the generated electrons influence the energy treatment area two to three times greater than what is necessary to break the molecular bonds on the surface.
This causes the free radicals to react quickly with the oxidation of products in the corona discharge or adjacent free radicals on the same or another chain, resulting in crosslinking. Surface oxidation increases the surface tension or surface energy, which allows for better wetting by liquids and promotes adhesion.
In the photos above note how the water droplet has a lower contact angle on the corona treated surface. Clear proof that corona treatment creates significant improvement in functionalizing surfaces.