2006-06-22 10:04:58 · 12 answers · asked by someonelikeyou 2 in Science & Mathematics ➔ Other - Science
Glue and a solvent reside in a bottle of glue. The solvent keeps the glue from sticking inside the bottle.
When you squirt the glue out of the bottle onto a piece of paper or a broken china cup, the solvent gradually evaporates, allowing the glue to get sticky.
The solvent molecules bounce and jiggle at the surface of the glue-solvent mixture and some get enough energy (when neighbors slam into them) to escape. That's evaporation. Outside of the bottle, few solvent molecules remain near the spread glue to hit it and renter the mixture. So, gradually enough solvent molecules leave the mixture that the glue gets sticky.
It's different in the capped bottle. The solvent molecules evaporate inside the bottle-just as they do outside the bottle when you spread the glue. However, once airborne they don't have far to go. They're trapped in the bottle. Some of the solvent molecules near the surface of the glue bop into and reenter the glue. That's condensation. Gradually--as more and more solvent molecules crowd into the airspace above the glue-solvent mixture--more and more solvent molecules reenter the mixture. Until, eventually, as many solvent molecules leave as reenter and the mixture reaches equilibrium.
Glue manufacturers make sure the glue mixture stays runny by choosing a sufficiently small air space when they fill the bottle. You may have noticed that old glue in an almost empty bottle gets viscous or even solid. It's a good idea to buy only enough glue for use in the near future.
As far as sticking to the bottle is concerned, here's the poop from Elmer's glue: "If it were to dry out or harden, it would form a very weak bond with the special nonporous plastic used to make the bottle and could be de-bonded or removed easily," says Robert Thompson.
2006-06-22 18:48:22 · answer #1 · answered by Anonymous · 0⤊ 1⤋
After applying glue, parts must be held together (with clamps?) until the glue cures. Depending on the type of glue it may have to cool, or evaporate water or some other volitile liquid or absorb air or moisture. Some epoxy glues require two chemicals to be mixed. Curing often permits the glue to form long hard chains from liquid. The glue bottle (or tube?) often lists materials that the glue will (or will not) stick to. With the cap on the bottle or tube the glue can not cure. If the cap is left off the glue many or may not stick to the bottle or tube. Even more important, the glue should not stick the cap to the bottle or tube when a small amount of exposed glue at the cap cures. Chemists can determine proper materials for the caps and bottles such that the molecules of cured glue will not adhere to them.
2006-06-22 18:00:22 · answer #2 · answered by Kes 7 · 0⤊ 0⤋
It is too much glue to dry up inside the bottle. If you leave just a film of glue in the bottle it will get hard and dry up.The glue must have air in order for it to harden. Ever notice that when you leave the top off the bottle, the tip of the bottle gets clogged up with glue?
2006-06-22 17:13:12 · answer #3 · answered by the sealer 3 · 0⤊ 0⤋
well, you'll notice that glue will stick on the lid if it leaks out, but not on the inside of the bottle. It's becuase the contents of the bottle haven't hit the air to dry out. Leave the bottle open for a long time and it will stick to the sides.
2006-06-22 18:23:08 · answer #4 · answered by solitusfactum 3 · 0⤊ 0⤋
See, in the bottle, there's little air. What makes the glue move is the water in the glue. In the bottle, there's no air, so the water doesn't evaporate. When it leaves the bottle, or the bottle is left open, the water evaporates or dries and sticks things together. We say it dries because it loses the moisture by evaporation.
http://www.asktaco.com/qanda/view/qid-1028?sessionid=cf488f82bdab3a7ec3a21021eaae181f
2006-06-22 17:13:07 · answer #5 · answered by bjm_116 2 · 0⤊ 0⤋
Because its still a liquid. Only after glue hardens when it comes to contact with something else does it stick and glue things together.
2006-06-22 17:09:37 · answer #6 · answered by tommynycity 2 · 0⤊ 0⤋
It depends on the chemical properties of the glue and those of the bottle. Think of oil and water, sort of like that.
2006-06-22 17:08:42 · answer #7 · answered by Anonymous · 0⤊ 0⤋
Because the plastic the bottle is made of cannot adhere to the adhesiveness of the glue.
2006-06-22 17:08:45 · answer #8 · answered by Anonymous · 0⤊ 0⤋
The inside of the bottle isn't stickyable unless you leave the lid off for a while, so I guess it must be the air :)
2006-06-22 17:09:48 · answer #9 · answered by Mummy of 2 7 · 0⤊ 0⤋
All of the air is pumped out of the bottle
2006-06-22 17:08:21 · answer #10 · answered by jgcii 4 · 0⤊ 0⤋