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Help locating Acetone resistent clear, rigid, plastic tube?

I have an application in which I need to encapsulate some small electronics in thin walled clear plastic tube. The electronics will be packed into the plastic housing tube (~ 1 dia. x .025" wall) with some dry glass microspheres and then capped on both ends. A VERY low viscosity epoxy (around 400 cPs, mixed) will then be injected through a small hole in one of the endcaps and allowed to wick through the microspheres. My problem, having found a suitably thin epoxy and done some test runs with this technique is that the epoxy (or perhaps hardener) is causing the Lexan tube to craze. I have a very small sample of some unknown plastic tube that doesn't have this problem but cannot identify it. It looks and feels like Lexan as far as its rigidity and scratch-ability but I've noticed it is impervious to acetone (while Lexan, Acrylic definitely are not). I'm hoping that if I find a plastic that can handle the acetone it will probably be good with the epoxy too. Unfortunately the several other epoxies I've tried that don't attack the Lexan are too thick to wick through the microspheres. I'd like the tube to be clear as it allows me to visually monitor the wicking action. Any suggestions would be gratefully accepted. The hardener for the resin system I've chosen (System 3 Infusion resin) says CORROSIVE on the label and may be part of the issue.

Reply to
jim
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You may try teflon tubing. Although it is not completely transparent, it is translucent...you probably will still be able to see the wicking action. In fact, your tubing wall is thin enough that you probably will not have problems seeing through the teflon. Also, Teflon is chemically resistant to most common solvents, including acetone.

Hope that helps...

Reply to
N. Ron

An expensive solution is to find a silk screener that can apply a clear silicone coating to the tubing--similar to the AR coating that Polycast Corp puts on their acrylic sheets to resist scratching--it's resistant to acetone--has to be removed prior to gluing the sheets. Also, look for clear PVC tubing--the rigid type, manufactured by Thermoplastic Corporation, may be resistance to acetone.

Lyle

Reply to
Fobg2000

Hi!

I think you are drawing false conclusions. To my knowledge lexan is a polycarbonate, not an acrylic. Widely used hardeners for epoxies are poly-amines (DETA, TETA, ...). Because of their basic character this amines are corrosive. Polycarbonate on the other hand is not stable against amines. What you need is a clear polymer which is inert under basic conditions, so acrylics should be a possibility. There are also some more or less transparent grades of polypropylen available or you could try something like Ticona Topas (a cycloolefinic copolymer).

Of course, changing the hardener is also possible

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offers some alternatives). Not sure if you will find a non-amine that reacts readily at room temperature.

Regards, Oliver

Reply to
Oliver 'Ojo' Bedford

I don't have my reference books here with me today, so I'm going by intuition more than solids facts. Nonetheless, polystyrene might be worth a shot. PS normally has lousy solvent resistance, but that tends to be more with nonpolar solvents (don't try keeping any gasoline in a styrofoam cup!).

John

Reply to
John Spevacek

Oliver 'Ojo' Bedford wrote:> Hi!

Yes.

I was going to suggest that also (I met with several Ticona guys a couple of weeks ago, coincidentally).

I'd also suggest looking into cheaper plastics like PET and PBT.

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Reply to
bob

Acetone is quite a good solvent for PS.

Oliver

Reply to
Oliver 'Ojo' Bedford

Whatever translucent fingernail polish remover bottles are made out of should work since fingernail polish remover is mostly acetone.

Reply to
ken Shockman

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