Comparing Flame, Corona & Plasma to Improve Surface Energy

Increasing the material’s Surface Energy 

As we all know that some plastic substrate materials are non-stick due to their low surface energy. Some common polymers like polypropylene, polyethylene, and PTFE (Teflon), as well as certain rubbers like EPDM and Santoprene, are typical “offenders.” These materials can be difficult to attach with industrial glue unless: You increase the material’s surface energy by different treatments such as flame, corona, or plasma.

Let’s first discuss surface energy before comparing these three treatments.

What is surface energy?

Surface energy, also known as surface free energy, is considered free energy on the surfaces of various materials. This energy creates activity or causes anything to happen in the thermodynamically purest sense. 

Surface energy may also be characterized as the additional energy present at a material’s surface relative to its bulk or as the labor needed to create a certain surface in a given region.

In manufacturing, regulating surfaces involves managing the surface energy of the materials employed.

Improving surface energy with different treatments with Pros and cons

All three of these techniques use tools specifically designed to chemically change a material’s surface to be more conducive to adhesion.

Plasma treatment

Plasma treatment has two important types: atmospheric and vacuum. Both kinds oxidize them, which changes the surface. Vacuum plasma therapy is carried out in a chamber that has been vacuumed, and it gives the user better control over factors such as composition and ratios. It is hence the preferred technique for coatings. For example, extremely specialized gas compositions are needed to generate protective or non-reflective coatings on eyeglasses, but this procedure involves more processes and takes longer.

In contrast, atmospheric plasma treatment applies to smaller treatment regions since it has fewer restrictions and employs a nozzle that draws its gas straight from the atmosphere.

Corona treatment

The method used in corona treatment involves the discharge of high-voltage, high-frequency electricity from an electrode located in a ceramic tube that extends the whole length of the roll of material that has to be activated. The material is wrapped around an electrically grounded metal roll known as the treater roll, through which the electricity is transmitted.

Flame treatment

In flame treatment, hot, oxygen-rich plasma is produced by carefully balancing a natural gas and air mixture. Heat first eliminates impurities. After the contamination has been eliminated, the oxygen-rich plasma partially oxidizes the surface to activate it.

Typically, low-energy surfaces like plastics and composites that might be challenging to cling to are treated with this method. Because the flame is the hottest of these processes, polymers treated with it may be more likely to melt or to produce LMWOM, or low-molecular-weight oxidized material, which may disrupt bonding. Examples of LMWOM include aliphatic hydrocarbons.

All of them are quite successful at getting a surface to the right level of cleanliness, but here are a few things that you need to keep in mind:

  • Under- or over-treatment of parts might have a negative effect on adhesion.
  • Because these techniques are not intended to remove oils, an excessively dirty mechanism could not be cleaned adequately.
  • Excessive treatment may volatilize and harm the surface, which would be bad for adhesion.

Frequently Asked Questions

 

Here are some important questions related to their comparison.

Why is surface energy important?

When choosing your adhesive, the bonding surface and its surface energy are important factors. For liquid adhesives, “wetting out”—where the glue spreads across the surface to optimize the attractive forces between the adhesive and the surface—is required for best adherence.

What determines surface energy?

For example, for the proper flexographic ink adhesion to happen. As a general rule, the substrate should have a dyne level (measurement of surface energy) that is at least 10 dynes greater than the surface energy of the ink that has been applied to it.

A combination of ethyl cellosolve and formamide is the widely recognized method for determining dyne levels or surface energy. 

What does surface energy mean?

Surface energy is a word used to refer to the extra interaction energy present at a substrate’s surface.

What does high surface energy mean?

As surface molecules are so strongly attracted to one another, they are also quite happy to be attracted to liquid molecules. Because of this, these materials are quite simple to wet out and bind. 

What is the difference between surface tension and surface energy?

Surface energy is the attractive force at a solid material’s surface. This force binds a material together into a coherent shape. Surface tension and surface energy are identical terms for solids and liquids, respectively.

How can the surface energy be improved?

There are specific strategies to raise a substrate’s surface energy.

  • Thorough cleaning
  • Verify the surface is completely dry.
  • Texture the Surface
  • Chemo-etching
  • Plasma
  • Utilize a primer