Material

http://www.coleparmer.com/Chemical-Resistance

Don't use silicone anything if you ever want to paint it.

I don't know what you're working on, but the specifications for various materials are easily found on the internet.

The two materials are almost like twin brother in properties, that's why the question.

Depends what you are trying to do. This general education question is much too broad.

You should learn, How to Search the Internet Effectively.

General knowledge can be googled, I am asking for more specific real experience .

You know how I feel about GlobalSpec, right?

Here is a useful link to drive traffic to my employer's site!

http://www.globalspec.com/learnmore/materials_chemicals_adhesives/plastics_elastomers_polymers/elastomers_rubber_materials

YAYYYY!

Oh. Or what lyn said...that works too.

Yes,

we should give credit where credit is due! Thanks to Search GlobalSpec for throwing this gig.

Is it just me?

When I looked, I got:

The link is broken, because the the last word "materials" in the URL was not complete. Fix it , it works.

Thanks for the link, the link URL is faulty, I re post it here http://beta.globalspec.com/learnmore/materials_chemicals_adhesives/plastics_elastomers_polymers/elastomers_rubber_materials

Nornally you don't choose, the choice is already done: U packs and others hydraulics seals are polyurethane material, high temp (less high than viton) shaft seals are silicon rubber high temp wires (less high than glass type) are covered by same.Iron wheels sometimes are covered by polyurethane and not by pvc as commonly happens.You may choose use silicone for gaskets in engines instead originals with great result, even exhaust joint with some copper mixed with.-

We use polyurethane sealant instead of silicone when we need better rigidity or bonding properties. Parts bonded with silicone can be peeled apart. If you use polyurethane it takes substantial effort to separate the parts. In our application we are not concerned with the chemical resistance, we use the polyurethane as a light tight gasket.

In general, urethanes have better tear resistance than silicones although silicones can be mesh reinforced to improve tear resistance. Silicones are considered implantable in animal tissue, urethanes not. Electrical insulation of silicones tends to be better than urethanes, which is one reason it is often used as an encapsulant for electronic devices. Urethanes tend to be tougher than silicones and are frequently used for mechanical applications. Silicones come in water white varieties that are useful for optical applications; urethanes not so much,

GA ! You gave a very good summary ! Much thanks.

To Lyn, this is what I am looking for!

It depends on who she is.

Have you looked at polyurea? Similar to polyurethane excepst it's stronger, has a much higher moisture tolerance, sets in 8-15 seconds, is totally inert and lasts forever. I'm specifying it for some major waterworks jobs in the UK. Brilliant stuff.

Not sure what your intended application is but check out Prokol Polymers in Holland.

Good piece of info.

I am using it to coat PP plastic , to be used for long term exposure to water and sun light, were you using for sealant or coating?

I'm using it to waterproof the top of a some concrete water treatment tanks. About the size of a football pitch. The material is sprayed on, sets in about 10 seconds and is backed with a 30 year warranty by the manufacturer. I have also specified a solar reflective, uv-stable top coat to reduce thermal expansion in the concrete slab and a non-slip surface for people to walk on it safely.

The manufacturer I would recommend is a Dutch company called Prokol as they are extremely careful to monitor the companies who apply their products unlike some others I have come across. Their QA systems are very good.

They have a cool video on you tube; Polyurea in a carton box - Prokol The Netherlands

www.youtube.com/watch?v=sfAImLhGLP4

Awesome material! What is the cost like?

My total cost for a 4500m2 tank sprayed with a 2.5mm thick coat, UV stable pigmented topcoat, 1550linear meters of joints, 400m of cut-in edge detail and caulk plus 200 x drainage hole dressings is just over £275,000 including the cleaning of the concrete surface. The 2.5mm coat allows it to be trafficked with no danger of puncture. You can have it thinner or thicker depending on the usage.

The material for this job is about £31/m2 and the application and preparation works out about a similar amount. The antislip surface texturing (To British Standards quality)costs about £4/m2 as does the UV topcoat so there are savings to be made depending on your application. I was able to save £40k by not having to cover the tank with gravel which is the normal requirement for thermal protection to a concrete roof slab in the British Water Industry.

On this contract I have a total of 4500m2 on one tank, 3000m2 on another and 1600m2 on a third and the per meter costs are all similar.

The Dutch manufacturer is also applying for approval from the British Drinking Water Inspectorate for it's use in contact with potable water which is the highest level of approval in the world. That's the reason I chose Prokol over several others.

This comes with a 30 year guarantee and should not require any maintenance.

I am also using it as part of a security application spraying the inside of a blockwork wall for protecting secure plant against blast damage. It's amazing stuff!