How does glue stick things together? Can anyone elaborate?
2$\begingroup$ Related: physics.stackexchange.com/q/135626/2451 , physics.stackexchange.com/q/314140/2451 $\endgroup$– Qmechanic ♦May 15, 2018 at 18:30
Most glues are made up of polymers. When polymers are wet, they're sticky; as they dry, they become hard (which creates a bond between the items where the glue has been applied).
When glues were made from processed animal collagen, they worked in much the same way. A gelatin of collagen acts very much like the modern polymer glues of today.
In the case of epoxy resins, one way to think of them would be to think of welding. As an epoxy cures, it undergoes an exothermic reaction (not all epoxies undergo such reactions) which activates the hardeners in the resin and makes a semi-permanent bond between two or more surfaces.
2$\begingroup$ Oh yeah, I guess it makes sense because when you think of hot glue, it's totally obvious: when it's hot, it's liquid, and when it gets cold it creates a bond between the solid it's sticking to? $\endgroup$– SparkleMay 15, 2018 at 15:45