Thread: Glue

I'm doing a science fair and I'd like to know if leaving glue in the open makes it stronger or weaker. I've tried super glue, white glue and a glue stick and I've obtained my results, I just need to back them up. I applied different weights to the glues after leaving them to dry for 1, 6 and 24 hours. Can anyone tell me what happens scientifically and some sources would be nice, but an explanation as well.

If you want sources, why can't you find them yourself?

I have tried but no where (that I can find) on the internet are there sources of how time affects glue. Thats what I wanted to know if there may have been a book about glue. I would also like an explantion on how glue works.

Originally Posted by bob22

I have tried but no where (that I can find) on the internet are there sources of how time affects glue. Thats what I wanted to know if there may have been a book about glue. I would also like an explantion on how glue works.

Try Google first off

Perhaps search for "effects of aging on glue"

or "how does glue work"

Yes you can actually ask a question in Google and most of the time you get an answer.

Originally Posted by (In)Sanity

Originally Posted by bob22

I have tried but no where (that I can find) on the internet are there sources of how time affects glue. Thats what I wanted to know if there may have been a book about glue. I would also like an explantion on how glue works.

Try Google first off

Perhaps search for "effects of aging on glue"

or "how does glue work"

Yes you can actually ask a question in Google and most of the time you get an answer.

In most cases that would be a good first step.

However, the "science" of how glue works is not very advanced. I looked into this once, and quizzed several adhesive chemists, without much satisfaction. Basically the advice is to prepare the surface, degrease it, and keep pressure on the bond while the adhesive cures or dries. There are many different adhesives and they work in very different ways.

You can find a lot of information on the chemistry of various adnesives and how they cross-link and cure. What you don't find is a good explanation of how they make two different materials stick together. It is generally not a chemical bond, but more commonly some sort of mechanical bond or entqnglement of large molecules.

There is no hard and fast rule as to how adhesives age. In the aerospace industry there are expensive aging and surveillance programs designed to study the aging of materials and bonds over long periods of time. They are purely phenomenological, and the underlying theory is poorly understood.

The OP mentioned several different glues, that operate in very different ways. There is unlikely to be any unifying principle that addresses the aging behavior of all of them.

I think the typical mechanism is hydrogen bonding with the surface, although a covalent bond may also be possible on certain surfaces through a substituation reaction. In the case of most superglues, this is then followed by polymerisation so that the glue itself is hardened, from liquid monomers. My guess would be that the glue only begins to polymerise when in contact with some partially-charged surface (including metals with delocalised electrons) so that the monomers can become hydrogen bonded to it; affecting the partial charge of the molecule elsewhere allowing it to begin polymerising.

This being the case (I would advise checking this by googling), high temperatures would cause the polymer to break up, as would exposure to UV light, and high/low pH solutions may catalyse the breakdown of the monomer. When the glue is broken by a weight, as mentioned in the OP, the force from the weight breaks intermolecular forces between polymer chains so they 'slide' past each other untill they are completely seperated.


So, things you might want to look at are exposure to UV light, temperature, and pH. That should be plenty for your project

The OP mentioned several different glues, that operate in very different ways. There is unlikely to be any unifying principle that addresses the aging behavior of all of them

When the glue's wet, not as much force is required to break of the bonds but when it dries, more force is required, while 24 hours is the curing time for both the glue stick and the PVA white glue.

Thanks guys, but the reason I did resort to using this forum is because I had no luck with google.

It's 'adhesive ' not glue .Glue is an old term for a sticky substace derived primarily from animal hoves and other animal parts. adhesives cure not dry.
anyway how are you evaluating the effect of time - a tensile test I presume?
I think your sciece fair will be history before you get any meaningful results.