Glue for polythene?

Heat. They melt together quitr nicely.

Not much, and not cheap or easy.

For real strength you can use a structural adhesive like 3M's ScotchWeld DP8005, but it ain't cheap (the first ten grams, plus necessary applicators etc., will set you back the best part of £100) - or, for lesser strength, flame treat the surface and try a really good polyurethane.

You can also use many of the surface treatment, adhesive and "welding" products used for polypropylene bumper repair in the motor trade, but I don't know much about them.

And that's about it, unless you want to get into *really* nasty chemicals, or explosive welding, or ...

-- Peter Fairbrother

I don't think I have any other options than melting the two parts and fusing them, potentially using some filler rod.

Chris

Might be worth experimenting with a hot melt glue gun...

Regards, Tony

Not a chance, IMHO. You might use the nozzle as a soldering iron?

You really need to specify more clearly what you are trying to glue.

Trying to make a balloon envelope from sheet PE without using welding (unless I have to) or adhesive tape.

Chris

Peter,

Any idea what the Scotchweld contains? If it's a solvent for polythene it must be something pretty unusual (but I bet it doesn't cost £10/g wholesale either).

David

Then I guess a bead from a hot melt gun might work, with the right combination of bead width, poly thickness, and time and pressure. Although I'd be concerned about controllability; cheap d/s tape or a pro welder seems like the right way to me.

Use a heat sealer, like polythene bags?

If you have to weld, you'll have to pre-treat the weld area just before welding, and use a filler from the car bumper repair range, wot I know nowt about.

-- Peter Fairbrother

I've had success with both a cyanoacrylate that comes with a special primer for low surface energy plastics and also an acrylic 2 part adhesive designed for such materials. Just had a look, the cyano is Loctite All Plastics and the acrylic 2 part is Super Crylic from Deluxe Materials; both were bought either from CPC or Rapid Electronics I think. Martin

Not entirely sure, but in general 1) grit to get accurate joint thickness 2) a fairly ordinary pmma acrylic adhesive and 3) some remarkable surface treatment agents. I used to know a bit more about the agents, but I've forgotten, would have to look them up (and I'm pretty sure they are proprietary).

If it's a solvent for polythene

No, only about 35p per gram in 5 gallon lots. But you need to buy a 35 gram package, plus an applicator, plus a pack of mixer/nozzles (it has a

7 second pot life, so you *really_need* these bits) - which will cost £100 or so - in order to do anything.

There's supposed to be a new one coming out with a longer pot life, I'm a bit out-of-date here and it may already be out. Might be cheaper to start with, though I have my doubts - but you may be able to mix it by hand, and not need the gun and nozzles etc.

There's also a Loktite one, but I don't know the number offhand and it's supposed to be not as good as the 3M one.

for googling, try "low surface energy" with the quotes

-- Peter F

I've tried Loctite/Bostic Super Glue with the 'All Plastics' activator pen successfully with PTFE, although I didn't try very hard to break the bond! Since they specifically state that it works with polyethylene and polypropylene I think it's the way to go. You paint the pen over the plastic surfaces to be joined, wait a minute for it to dry and then glue as usual. I'd meant to experiment with using the activator pen and araldite to see if it worked with that. Anyone tried that yet? I was so impressed with this new technology I spent a few hours researching it online. Seems such surface activators are already well known amongst the cognoscenti! Here's a couple of related links:

Scrim

welding

Overlap the sheets slightly, lay a strip of aluminium kitchen foil over the joint, and run slowly down the joint with a hot soldering iron. You used to be able to get a special bit that was just a copper rod with a slot cut in in, in which a copper disk rotated on a pin - I found that the heat transfer from the rod to the disk wasn't brilliant so used a well rounded and polished copper rod.

AWEM

Jim Finn, the noted biologist, was stumped. He had spent months studying the little green frogs in the Keefo swamp. Despite all efforts at predator control, population was declining at an alarming rate.

Finn finally went to the chemistry department at his college to see if anyone there might be able to help. Tom looked into the problem and came up with a solution. The little frogs had succumbed to a chemical change in the swamp's water and simply couldn't stay coupled long enough to reproduce. Tom brewed up a new adhesive, made from a dash of this, a zoss of that and, most critically, one part sodium. "You mean...?" said Jim.

"Yes," said Tom. "They need a mono-sodium glue to mate!"

Thanks Peter

David

John -

How many layers of dust did you have to shift to find that one? ;-)

Regards, Tony

Thanks folks. Looks like I'm gonna have to do some prototyping. I've got a nice temperature controlled soldering iron so a combination of that with a suitable tip or a hotmelt glue gun with a controlled feed rate will probably work.

Chris

I have the impression that John can't see the dust for all the swarf on the floor

Cliff Coggin.

Not used it myself but they claim their universal bonding pack works on Polythene, PTFE and Delrin!

Jim