Chapter 2: Background Ideas

We start by looking back at how adhesives developed over the thousands of years from when Neanderthals worked out the surprisingly tricky art of converting birch bark into an effective glue for arrowheads, through Egyptian craft workers gluing together sophisticated furniture right through to the first industrial-scale use of skin, bones, milk, blood, eggs or just about anything that could be transformed into a sticky polymer. Although these adhesives are renewable and (just about) “natural” few of us would accept their many limitations, hence the need for modern high-performance (and planet-friendly) adhesives. Then it's time to make sure the basics are in place via gentle introductions to some core science ideas without which adhesion makes no sense. We need to agree on the meaning of measurement units, note some simple things about chemicals and polymers, and find out about some essential bits of mechanics such as the meaning of adhesion strength values and the dire effect of defects on adhesion. Add on the surprisingly important science of squeezing drops of glue and we have about all that's needed for the rest of the book.