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Ed Nye
11-13-2001, 03:14 PM
Now that I know how to cut it. How do you structurally glue Acrylic, i.e. Lucite. What about glueing polycarbonate, i.e. Lexcan.
Thanks, Ed

Ian McColgin
11-13-2001, 03:44 PM
Gluing pieces together ?
v.
Attaching into something else?

Solvents v. 5200.

ken mcclure
11-13-2001, 03:44 PM
Cyanoacrylate for acrylics. (Crazy Glue) Not sure for the rest.

thechemist
11-13-2001, 04:11 PM
Weldon 3 or Weldon 4 are good solvent cements. For best results, use PS-18 or PS-28 as the polymer cement. Vacuum deaereating is usually necessary to eliminate all bubbles before application. Your acrylic supplier should be able to get these for you. Annealing is vital after any fabrication operation.....sawing, drilling, buffing, whatever, in order to avoid crazing.

Ed Nye
11-13-2001, 04:57 PM
OK, I don't completely understand the answer. And I guess the question wasn't complete. I have a broken plastic zismo (some kid at the boat show jumped up and down on it). It is either acrylic or polycarbonate. I don't know which, I didn't build it. And I want to put it back together again. Can you glue both acrylics and polycarbonates with the same solvent cements? Or is it solvent for acrylic and polmer cement for the polycarbonate? How can you tell an acrylic from a polycarbonate?

I'll take my answer off the air!!!!
Ed

thechemist
11-13-2001, 08:51 PM
Well, it might be of general interest......

Polycarbonates such as Lexan do craze in the sunlight, and in a few years their strength is down to that of acrylics. Last I heard, a coated polycarbonate, CR-39, originally developed for welding goggles, does better in sunlight.

Polycarboates can be solvent-cemented with ethyene dichloride [EDC]. That is a not-very-good solvent cement for acrylics, although it does work. Ethylene dichloride with ten percent diacetone alcohol is a better solvent cement for acrylics, although Weldon 3 or 4 are much better.

Some acrylic sheet is radiation-crosslinked in the curing process, and is not gluable, except with cyanoacrylate cements.

Try a bit of Duco Cement from your local model shop. It comes in a metal tube and used to have EDC in it, as I recall.

Many plastics can be identified by putting a match to them, heating a corner to flame, blowing out the flame and quickly but cautiously smelling the smoke. The monomers and decomposition products have characteristic odors. This is only for professionals. Don't try this at home.

gashmore
11-13-2001, 10:05 PM
Acrylic is not actually glued but solvent welded with methylene dichloride. Go to your local PPG glass store and ask for Craftics acrylic solvent cement and an aplicator. The aplicator is a length of capilary tube on a squeeze bottle.

The edge to be glued has to be a very good fit. Straight and square. Haze it up with a light sanding with 150 grit. Set it in place and run the aplicator around the joint. If the fit is good, the solvent will suck up into the joint. Add some pressure to close up the joint as the acrylic softens. Hold it still for about 2 minutes then let it cure for a few hours.

You can glue polycarbonate with methylene dichloride using the same technique but it is not quite as strong.

Syd MacDonald
11-13-2001, 10:42 PM
I read somewhere recently (maybe something from Gougeon Brothers) about preparing a plastic surface for gluing with epoxy by heating(charing) the surface with a torch. Can't remember the details but you might call them.

bainbridgeisland
11-13-2001, 10:43 PM
I regularly use an acrylic adhesive (Versilok with accelerator #17)to glue plastics together. It has very low surface energy so it wets most surfaces. It's pretty tough too. I wonder how well it would work with polycarbonite sheets. Has anyone tried it?


[This message has been edited by bainbridgeisland (edited 11-13-2001).]

Ron Williamson
11-14-2001, 05:39 AM
Ditto,the methylene (di)?chloride,but wear a respirator or leave all of your brain cells in a safe spot before you open that stuff.
R

Ed Nye
11-14-2001, 02:55 PM
Thanks, for your input, Ed

rainy27
11-14-2001, 04:46 PM
One note of caution that I am not sure anyone mentioned should you try the "quick" fix with superglues. You should not use cyanoacrylate based glues for polycarbonate as the will leave a clouded appearance around the joint after cure. In addition, I have not had good luck using these glues for permanate plastic bonds that could be impact loaded. Finally, if you are going to use one of these glues be sure the bottle is either new or has not been opened for very long (<1 week, a guess). These glues tend to age quickly once the bottle has been opened. The result may be a bonded joint with less then ideal strength.

Jamie Hascall
11-14-2001, 04:50 PM
Ed,
I just checked out the adhesives chart in the back of the Laird Plastics catalog and they list Weldon # 3, 4, and 16 to all be suitable adhesives for both acrylics and polycarbonates. I think it's mostly a matter of viscosity and drying time, but the #4 is listed as a little slower drying with less of a tendency to blush (probably on acrylics). I think you might be good to give Laird a call at 206-623-4900 for a definitive answer. They're great folks and who I talk to when I really need plastics and answers. Let me know how things turn out.

Rainy's answer came in while I was typing and he makes some good points. I think the idea of lower than ideal joint strength is probably a given as repair never seems to be as strong as new construction. You may want to give that gronicle case a little protection from young persons or it will not keep the weather off properly (and of course you know what that leads to...).

Good luck,
Jamie

[This message has been edited by Jamie Hascall (edited 11-14-2001).]