Urethane plastic vs rubber. What the difference?

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prospectsnow
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Urethane plastic vs rubber. What the difference?

Post by prospectsnow »

I've used some "Task 16 Urethane Plastic" from the guys at smooth on with 3 boards that I did a sidewall replacement on. If anyone needs to do that, this stuff is super durable and easy to pour in.

http://www.smooth-on.com/Urethane-Plast ... index.html

They also have "Econ 80 Urethane Rubber"
http://www.smooth-on.com/Urethane-Rubbe ... index.html

Same hardness and the Task Plastic is more durable, but the price of Econ Rubber sounds nice. Wondering what you guys have some hands on.

If all goes well here I'll be pouring these for a larger scale and I'd like to be able to offer these to everyone here.

Have a rad day.
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MontuckyMadman
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Post by MontuckyMadman »

The urethanes from chemtura will be better in all mechanical respects than what smooth-on has to offer. Much more industrial. Check the data sheets on the adeprines
just sayin.
sammer wrote: I'm still a tang on top guy.
prospectsnow
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Post by prospectsnow »

I checked out those urethanes.
Definately awesome stats.
The downside is that they need to be baked at 200F+ in order to cure. Plus it needs to be ventilated so you don't see unicorns and mermaids.

Anyway. Did some testing on the urethane. Had some guys at mt hood testing this summer and got thumbs up. Going to keep trucking on this.
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chrismp
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Post by chrismp »

i'm using chemtura's adiprene lf950a and i had the guys at chemtura do some tests with room temp cured samples. the samples performed nearly as well as the ones that got the 100°C cure cycle. so i'm only curing my sidewalls at room temp.
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Post by Richuk »

Chrismp, don't forget to give us all a 'heads up' when your company goes public : )
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Post by chrismp »

haha, same goes for you!! :D
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Post by prospectsnow »

A few questions...
How is the cost?
Can it be colored?
Does the part A/B need to be warmed to start the process?
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MontuckyMadman
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Post by MontuckyMadman »

5 bucks a pound
yes it can be colored and yes it has to be at 150f to be mixed
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mattman
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Post by mattman »

So I have worked with plenty of Smooth-On, but want to use one of Chemtura's Vibrathanes. The mixing and curing process that they describe is extremely intense. Do any of the people that have experience with their products (chris, montucky...?) know what parts of their procedure is critical and what is not. I am planning to pour and press the mix in with the ski, so the more similar it can be to the 180F, 2hr cure schedule we currently have (one of QCM's slower resins) would be ideal. I know you guys highly recommend Chemtura, but how far do you go to use them?
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chrismp
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Post by chrismp »

all i use is the lf950 resin which is supposed to be cured at 100°C for 16h but i'm only letting it cure at room temp without any additional heating. the properties don't change by much. i've had chemtura run some tests with room temp cured samples and there wasn't much of a difference between the heat cure and the room temp cure.
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Post by mattman »

Chris, thanks for responding. The lf950 data sheet says that the resin and hardener need to be preheated to 150F (66C) and 240F (116C), respectively, before mixing. Then molded at 212 (100C) for 25min. All that before the 16hrs at 212F (100C) demolded post cure. Are you doing the whole process at room temp? The PUs I am looking at have similar preheat and curing requirements.
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chrismp
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Post by chrismp »

Yes, I do pretty much the whole process at room temp. Here are the steps I go through:

- The resin usually crystallizes when stored for a while. In order to make it liquid again, I put it in the microwave for a couple seconds. This heats the resin a bit but not more than luke warm (can't say the exact temp, but it's just warm to the touch, so I'm guessing somewhere around 40°C).

- Then I mix resin and hardener (hardener is at room temp).

- (I don't do this step at the moment, but I'm definitely planning on buying the equipment since I now have access to a vacuum pump: degas the resin and hardener mixture to get rid of the tiny bubbles.)

- Then I just pour the mixture into the routed channel and let it sit for a couple of days.

I will post the emails with the test results from Chemtura when I get home.
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mattman
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Post by mattman »

Chris, thanks for the details (this is extremely helpful). Your mix has a claimed 7 minute pot life. Does this allow degassing? Or without the extreme preheating, do you find that the pot life is longer?
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chrismp
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Post by chrismp »

Yeah, that's a problem I'm aware of. It doesn't seem like the pot life is much longer than the 7 minutes from the tech sheet. I hope to be able to do the degassing in about 2 minutes. That would leave just enough time to pour the sidewalls.
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MontuckyMadman
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Post by MontuckyMadman »

the chemtura stuff is a serious PITA.
I degassed and heated three large pours to 150F and degassed and then cured at temp for an hour at 160f or whatever it calls for. the material hardens more with time. It was difficult to get a good degas with time and temp restrictions. If you were doing smaller pours it may be easier but with everything there is a learning curve.
THe material comes in industrial containers. You can just nuke them as they are made of steel. You have to heat and transfer and then if you dont use it all at once you have to flood the container with dry nuiotrogen or dry oxygen(what I had) like from a welding tank. Moisture will ruin the material. It smells toxic and definitely puts off toxic fumes when it cures.
It does not machine in the 90 shore A like uhmw, it clogs belts and is tough to cut with saws. I might consider trying the adeprine at a shore D hardness of 60-70 closer to what UHMW is. Impact strength and cutting resistance seems comparable to uhmw and does not crack like ABS can.
The smooth on stuff has much lower numbers for tear and shear and elongation and impact but may work well for snowboards. Skis are different in some respects to wear and materials needed.
I dont think I will be using the adeprine again soon do to the process.
But if you want colored sidewalls then its a good option. Prolly for the home builder and non commercial sale the smooth on work fine.
I have resisted uhmw sidewalls for years but in reality if you can get it to stick and profile then it seems like the best option for durability, especially impact Resistance for compressed edges. wood is not good for this unless it an exotic hardwood and then you have to retool for flex pattern changes. its always something...
sammer wrote: I'm still a tang on top guy.
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