Educational: Importance of Surface Energy

The first thing I would teach someone who is trying to learn about adhesives would be the importance of surface energy. Surface energy is how attracted a material's molecules are to each other. . In simple terms, it measures how easy a surface is to stick to.

It ranges from high surface energy to low surface energy, the higher the surface energy, the easier something is to stick to. A good example would be your non-stick pans. They have a coat of PTFE, more commonly known as teflon on the surface. They do this on purpose so that your food does not stick to it. PTFE is one of the lower surface energy substrates out there. Below is a quick guide on common materials and what level of energy they have.

The guide below is helpful, but I would still encourage you to give us a call if you need help bonding your substrates :)

Note: When someone is working on a new project they usually first come up with the design of a tool. They work with the molder on what material to use in the tool. There is a lack of education from the molders side on surface energy. They will recommend great plastics, but some of these plastics are almost impossible to bond to. I have ran into a lot of applications where once they got into the production stage and their product had been molded out of polyethylene. The company will either have to change their material or triple their spend on getting adhesive that will bond to the polyethylene.

High Surface Energy-

Basically all metals (aluminum, steel, tin, etc). When bonding metals, be more concerned with the strength of the adhesive as you are generally replacing a strong rivet, weld, or screw.

Medium Surface Energy-

Nylon, Phenolic, Polyimide, Wood, Cement, Glass, Ceramic

Low Surface Energy-

PTFE (teflon), PVC, Polypropylene, Polyethylene, EDPM, Polystyrene, Powder Coats