How to formulate the perfect adhesive

Jon Lawson

The first reported use of an adhesive was protecting cave paintings — around 70,000 BC, when cavemen in South Africa used a glue-like substance made from tree-sap. We now use a range of adhesives and bonding agents for different substrates and applications. Here Ramya Sriram, digital content manager of freelance platform for scientists Kolabtree, discusses how a freelance formulation chemist can help you develop and test your adhesives. 

The global adhesives and sealants market is expected to reach US$82.4 billion by the year 2025, according to a report by Grand View Research. The growing market is benefitting from developing adhesive chemistry — materials are now capable of undergoing shock, vibration, extreme temperatures and many other destructive agents without breaking apart. 

Adhesives can join, seal and protect components and are used widely in the construction, assembly and automotive sectors. They’re a cost-effective solution, suitable for many applications. For example, the automotive industry uses adhesives to bond interior parts during the manufacturing process, as well as eliminate rivets and reduce weight. New adhesives are being developed to meet the needs of a changing market, for example to be more environmentally friendly.

What are the sustainable alternatives for adhesive?

While adhesives play an essential role in the working life of a product, they can cause problems later on — adhesives can make products difficult to recycle. According to the UN, 20 to 50 metric tonnes of electronic waste are discarded every year, making recycling a pressing issue.

The components in electronics, such as smartphones, are commonly bonded with adhesive, as it is lightweight and can provide a protective coating. However, removing an adhesive to recycle a device can be time consuming, expensive, damaging to the components and require harsh chemicals. One emerging solution, developed by Karlsruhe Institute of Technology, is a reversible adhesive, which disintegrates at higher temperatures, so that it can be easily removed. 

Electronics is not the only sector that requires innovative sustainable adhesives. In another example, Henkel Corp, a global manufacturer of adhesives and sealants teamed up with TerraCycle, which specialises in hard-to-recycle waste including coffee capsules and laboratory waste. TerraCycle discovered that Henkel could dispose of its anaerobic bottles by curing the adhesive residue first. Anaerobic adhesives remain liquid as long as they’re exposed to oxygen, which means shredding the bottles could lead to the adhesive leaking. Once anaerobics have been cured, the adhesive becomes a hard plastic and can be recycled. 

Once a new adhesive has been formulated, the next step is to evaluate their strength and effectiveness. Shear tests, tensile tests, cleavage and peel tests will give you some basic mechanical properties of the adhesive.

Whether you’re developing your own bonding agent or designing or assembling a product that you want to recycle, it’s important that you can access the specialist knowledge and expertise that’s required. Developing new products in response to market change is not an easy feat. One way it can be made easier is to work with a freelance formulation chemist, who has experience formulating new, alternative adhesives.