Adheres to adhesives – news from ULaval

They can join a variety of different materials together, carry a 2,000 kilogram load on a small adhesive surface, and even be sent into space. Since the first patent in 1814, the number and specialty of adhesives have exploded. As part of a new series of general public conferences from the Faculty of Science and Technology, Professor Michel Guillot is lifting the veil on this growing field that he is investigating with his research team.

Adhesives accounted for $49.5 billion in sales in 2016, then $63 billion in 2021. “In two to three years we will probably exceed the 100 billion mark,” predicts the professor from the Faculty of Mechanical Engineering. And for good reason, you can find them almost everywhere, he lists the possibilities. In electronics, they enable microchips to be fixed in a plastic housing. In aerospace, they are used to assemble thin walls and minimize their weight, “a very important factor in space,” while at the same time withstanding temperature fluctuations and solar radiation. When healthy, they can adhere to “living creatures, bones, tissue.” Not to mention their applications in construction, household appliances and transportation.

Why use adhesives instead of welding or good old rivets and bolts in industrial vehicle assembly? the speaker asks. For aesthetic reasons he answers first, explaining that they leave no marks, no holes, but a smooth surface that is easy to paint. Adhesives also increase stiffness and durability and reduce sheet metal vibrations and noise. They maximize the effectiveness of the connections and prevent moisture penetration between two metal parts, which can lead to galvanic corrosion.

There have been many developments in the last decade, continues Professor Guillot, and car manufacturers have adopted them on a larger scale. A car today consists of 110 to 120 meters of structural adhesive. Here too, one of the big advantages is the weight reduction by an average of around one hundred kilograms. Electric cars also represent a market with great potential, especially for battery assembly, the speaker emphasizes.

Important moments in the development of adhesives

1814 Patent for the first adhesive made from animal bones
1872 First production/patent of a glue made from fish bones
1875 Start of lamination of thin layers of veneer wood (plywood)
1917 Adhesive for aircraft construction (casein)
1927-1930 First rubber-based adhesive (1927), first printing tape (1930)
1930-1940 New adhesives: acrylic, polystyrene, PVC, polyethylene, etc.
1944-1948 First adhesive for metal (1944), first adhesive made of epoxy resin (1948)
1960 Cyanoacrylate (superglue)
1970 Adhesives that can withstand a temperature of 500°C
1970-1990 Other curing methods (liquid hardener, UV, heat)
1980-2010 Improvement of adhesives. Many brands, reputable products, higher trust, more testing and data, etc.
2010+ More specialty adhesives, improved adhesion, less preparation effort, structural use in automobiles

Research and standardized testing

Professor Guillot and the team he leads have been researching adhesives since 2006. In a partnership project with Styl&Tech Inc., they participate in the design of the structure of electric buses, mainly made of aluminum. Tests on specific sub-assemblies showed that the product was “structurally very efficient and approximately 30% lighter than that of competitors that do not use bonding.” The researchers also plan to collaborate on testing the full-scale prototype.

People who are unfamiliar with adhesives often have concerns about long-term strength and durability, says the professor. “These are the things we study. We carry out tests to ensure that the adhesives are sufficiently predictable and usable in the design.”

In these standardized tests, researchers examine adhesion and creep, i.e. the deformation of an adhesive under the influence of a load; They carry out fatigue tests, impact and durability tests, for example in the presence of salt water, heat or frost, explains the professor. You can also evaluate the performance of an adhesive that has passed its expiration date.

Thousands of products and brands for everyone

Silicone, polyurethane, acrylic, epoxy… instant adhesives, with UV curing, two-component structural adhesives, adhesive tapes… It’s easy to get lost in the adhesive shelf. In fact, there are thousands of products and brands, so many that it is difficult to count them, says the speaker. However, in his lecture he gives an overview and mentions that, despite their specialization, many are accessible to everyone.

You can get it from supplier sites like McMaster-Carr or Amazon, he says, but also from regional industrial dealers who have inventory or can order it. “Technical data sheets are easily available on the Internet,” says the professor.

Which materials are glued? Does applying the glue have to be easy or are we able to prepare the surfaces? How long is the work expected to take, given that fixing and curing times need to be taken into account? Here is an overview of the questions you should ask yourself before choosing the most reliable product.

To watch Professor Michel Guillot’s conference:

The series of free conferences offered by the Faculty of Science and Technology’s Continuing Education continues. The next one will take place on December 12, when Céline Vaneeckhaute, professor in the Department of Chemical Engineering, will give a talk entitled “Resource recovery and recycling: from the toilet to the plate.”

Past conferences are presented in repeats and all of them are also offered in the business area.