Adhesive Education Series: Cohesion and Adhesion
At Bostik, we work in the adhesive industry every day. We manufacture adhesive solutions, help our customers use them and promote them at events. In doing so, we talk about two fundamental adhesive characteristics like “cohesion” and “adhesion” much like people talk about the weather and weekend plans. Adhesion and cohesion are important to adhesives because they directly affect the strength of an adhesive bond.
But, what do these terms really mean?
Cohesion: The tendency of similar particles to cling together.
Water droplets are an example of cohesion. Internally, each individual molecule is attracted to another, forming a network of water molecules that pull into a drop form. Adhesives can gain cohesion due to weak attractions between molecules similar to water or even due to strong chemical bonds or physical connections between polymers.
Adhesion: The tendency of dissimilar materials to cling together
An example of this in our every day lives would be water droplets clinging to the sides of a drinking glass. In nature, adhesion is when those water droplets stick to a spider’s web.That attraction between the dissimilar materials like water and glass or a spider web is adhesion. Adhesives can also bond to dissimilar materials through chemical attractions but can form even stronger bonds through a variety of other interactions. These interactions include physically locking to a material with a porous surface, forming strong chemical bonds, or by molecules diffusing into the surface of one another.
At Bostik, we specialize in developing some of the most versatile adhesives on the market. Web adhesives are one example of Bostik’s innovations, which are used to bond and laminate to a variety of materials, including textiles, nonwovens, foams, leathers and plastic film. We recently launched two new flame retardant web products, featured here. To learn more about our web adhesives in general, watch this video.
Got questions about our adhesive products and the technology behind them? Contact a Bostik expert!