Clear Plastic

[DaveE01]

I am looking for a clear injection moldable plastic. The environment the plastic will be subjected to is temperatures up to 275 degrees F and submersed in aerospace hydraulic fluid (Skydrol). The plastic is lightly loaded but needs to maintain it’s clarity. Any suggestion would be appreciated.

 

[Demon3]

At a guess I would say polyphenylsulfone. The reason I say that is that I heard that Stratasys made a rapid prototype of a car oil filter from that polymer and ran it on a car with hot oil pumping through it and high pressure. So, I'm not sure but that'd be my first guess.

There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[HDS]

fluropolyers might work.
You can get clear PCTFE.
PC will not work because of the hydrocarbon exposure.
Glass is an alternative.

 

[Pud]

Look up Trogamid (Degussa)trade name - it's Polyamide 6.3.T, or Grilamid TR (EMS Chemie) trade name - based on Nylon 12.

Others may make similar.

Cheers

Harry

 

[btrueblood]

I was going to say Poly-ether-sulfone, but I think that's what Demon3 meant to say, or it's a close second to his.

 

[Pud]

Ben,

I think Demon3 has been on the hyroxyethane, with several aldehydes added too, causing a digital malfunction...

PES - ok for hydrolysis, no idea re oils? Also narrow processing window. Drying prior to moulding critical, etc, etc. Plus it's got a yellow tint.

(Built them thar blades yet?)

Cheers boys

Harry

 

[btrueblood]

Pud,

The blades became paddles for a kayak trip last year, they worked great. I should post a picture in the pub one of these days. Haven't had a chance to paddle again lately; need to get the canoe seats rebuilt for duck season...also one of these days.

As for Skydrol and clear plastic...

Skydrol is a horrible thing to try and find compatibility lists for, it behaves in nasty ways as it gets hot, and polymers that are okay at one temperature will fail spectacularly at another. The answer to the OP is to test a few of the suggestions, but be open to the idea that the right answer may be glass.

Some backup for polysulfones:

This document seems to say polyethersulfone is okay (look up hydraulic fluid, where it says something about a phosphate ester mix):

http://www.basf.com//PLASTICSWEB/displayanyfile?id=0901a5e180004877

This reference just adds a bit more confusion,

http://books.google.com/books?id=s7...=X&oi=book_result&resnum=3&ct=result#PPA48,M1

where it reports polyphenylsulfone as incompatible (failure in 30 minutes) with 200 F Skydrol.

This list, published by the manufacturer of Skydrol, is incomplete in not listing the polysulfones, but does list nylon, polyamides, and polyimides:

http://www.skydrol.com/pages/materials_chart.asp

So, Pud's suggestions may get closer to the mark than any other.

The fluorocarbons, IMO, will tend to be too soft (ECTFE) and/or too translucent (unclear) at workable thicknesses to be of much use; YMMV. Try PVDF, PFA, if you can find them in transparent sheet form. PFA is not moldable, but PVDF can be?

 

[DaveE01]

Thanks everyone for the suggestions. Here is the list of clear plastics brand names that I have tried: Ultem 1000, Radel K-5000 NT, Trogamid CX7323, Rilsan clear G170 & G350, Grilamid TR-55 & TR-60, and Xylex 7519. They all failed to one extent or another. Hot Skydrol is some nasty stuff.

I am going to try Homalite H911 next. I do like the PCTFE option.

 

[btrueblood]

Ok, so to translate (I have to do this for myself, thought I'd put it in here to help anybody later on who's searching these posts)

Ultem 1000 = polyetherimide
Radel R-5000 NT = polyphenylsulfone (Dave, you did just mistype a K, right?)
Trogamid = polyamide
Rilsan = polyamides
Grilamid = Type 12 polyamide (nylon 12)
Xylex 7519 = polycarbonate + polyester mix

I would still try polyethersulfone, but won't hold my breath. Have you thought of using epoxy?

 

[Pud]

Another possibility:

http://www.topas.com/news-literature-brochures.

I thought this stuff was made by Ticona but they must have sold it off. Link is to .pdf brochure direct as most info here. Then there's TPX (Mitsui), but there's a complete lack of tech stuff on their website. Used for lab equipment. HDT may be bit low though...

Cheers

Harry

Ben: Good man - pics pse yes!

 

[DaveE01]

Thanks Pud. I just put in a request for some samples. I have a simple soak test I perform with Skydrol at 275F. I check it at 20, 100 and 200 hours.

 

[Pud]

DaveE01,Topas is slightly cloudy at melt temperature and clears as it cools. (Apparently, moulders have purged bags of the stuff through trying to get the machines clean - fortunately, I was told this beforehand!) I've never seen it heated up from cold though. Point to watch for.

You might try these:

http://www.hybridplastics.com/

I think they make a nano-reinforced Topas which is "sorta" clear. Properties you are interested in may be improved.

Cheers

Harry

 

[patprimmer]

TPX behaves much like PP.

It is a polyolefin, but has PC type temperature resistace.

It is both semi crystalline and transparent so it has typical crystalline polymer properties in general.

I have a lot of data on it at home if required.

TPX was in very short supply last time I enquired.

With other typically crystalline polymers that have transparent versions, the transparent version is amorphous and therefore exhibits some other amorphous polymer characteristics.

Reny is another transparent amorphous nylon similar to some grades of Grilamid. Transparent Grilamid comes in several types so just because one fails, others may not. EMS should be able to advis.

Solvay is also a good source of the exotic transparent polymers and as a large range of Keytone and Sulphone type polymers.



Regards

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[HDS]

Did you ever try the PCTFE or the PVDF?

 

[HDS]

One thing I don't think was mentioned is that the chemical resistance of many plastics depends on stress. You can take a piece of PC that is free of stress and one that is bent and spray them both with brake cleaner. The flat one will be o.k. the bent one will crack.

Even if your piece is lightly loaded injection molding can leave residual stress that lower chemical resistance. Sometimes these can be relieved by annealing.

So in your testing include a part that has a representative load on it.