The Evolution of Instant Adhesives
When Harry Coover invented the original cyanoacrylate adhesive more than 50 years ago, it seemed he had created the ultimate fast-acting adhesive. However, when you look at all of the different adhesives available these days, it now seems the best is yet to come.
Cyanoacrylate adhesives were essentially made up of methyl cyanoacrylates and ethyl cyanoacrylates. There was a saying that you should use methyl on metals and ethyl on everything else.
While it is true that methyl will bond better with metals and ethyl better with almost everything else, cyanoacrylates have improved so much that there needs to be far more said about your options when it comes to fast-acting adhesives.
Despite revolutionising adhesives, Coover’s cyanoacrylate adhesives did have some problems, as while they were fast acting and formed extremely strong bonds, their ability to deal with impact, extreme temperatures, and their poor water resistance made them less than perfect. Original cyanoacrylate adhesives also performed poorly on highly acidic surfaces.
As soon as it became clear that Coover’s efforts were imperfect, scientists began working to find ways to improve on the performance of cyanoacrylate adhesives, and they had massive success to say the least.
The advancements in fast-acting adhesives have been enormous, and the following are just some of the ways that cyanoacrylates have evolved to outperform Coover’s original cyanoacrylate adhesive.
Tougher — Modern cyanoacrylate adhesives are modified to incorporate rubber and other impact modifiers, enabling far greater impact resistance. Standard cyanoacrylate adhesives have an average impact strength of approximately 10 kJ per square metre, while modern cyanoacrylates can withstand an impact of up to 16 kJ per square metre.
Will bond to anything — Modern cyanoacrylates will bond even the most dissimilar of materials, and can be particularly useful for bonding materials where thermal expansion and contraction may be an issue. They will even bond impressively to acidic surfaces such as wood, cork and paper.
Non-blooming — Blooming can sometimes occur in standard cyanoacrylates, which is when liquid material is vaporising and reacts with moisture in the atmosphere, causing it to cure and fall back to the surface, often resulting in a dusty, white-coloured mark that can be difficult to remove. With modern cyanoacrylates, this is no longer a problem, as they use low-pressure monomers, enabling them to effectively eliminate blooming.
Resistant to high temperatures — Of all the improvements made to Coover’s adhesives over the years, the most impressive has been how much better they now are at dealing with high temperatures. While the original cyanoacrylate adhesive can withstand temperatures of up to 82 degrees Celsius, modern versions can deal with temperatures more than twice as hot, with some modern cyanoacrylate adhesives able to withstand up to 200 degrees Celsius. By providing a secondary cure, special cyanoacrylate adhesives can even be made to withstand up to 250 degrees Celsius.
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