autoclavable, clear plastic 1

[ramiroe]

Hi, I'm looking for an injection moldable plastic that is clear and can be autoclaved, yet something cheaper than polycarbonate. It must withstand an autoclave process, which is 250F(120C) steam for about 30 min, without visibly deforming, say maybe 5% max. I saw that nylon has some heat resistant resins, does anyone know if those can be clear?
Also how about Polymethylpentene(PMP) or Styrene Acrylonitrile(SAN), any others?

 

[Demon3]

PMP is wildly expensive due to over demand and one supplier.

Standard SAN won't work as the HDT is too low. High temperature SAN may work (copolymerized with either alpha methyl styrene or N-phenyl maleimide to increase HDT). Contact BASF and ask for Andrea Kirsch, tell her I sent you. The grade you need to ask about is called

Luran® HH-120 Highly heat-resistant specialty grade based on alpha-methylstyrene-acrylonitrile.

Vicat B is 120C so it's close.

COC would work but probably too expensive.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[patprimmer]

Chris is spot on.

Nylons won't work as the ones you can afford are not transparent at over about 1mm thick and in the amorphous state probably won't withstand autoclave or will go cloudy after autoclave. The high temperature clear or aromatic nylons are quite expensive. Same story for PET.

SMA (styrene maelic anhydride) might work. A common trade name is Dylark. I am not even sure if it is still available

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[Demon3]

Nice idea Pat. SMA could be worth a look as it is similar to high heat ABS. It is still available but under another name. However, I would be worried about the maleic anhydride units opening up under autoclave if there is moisture present. If so it could take up a lot of water then become plasticized and soft.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[patprimmer]

My experience with it was many years ago in a machine to make perfectly boiled eggs every time.

They tested for many hours (probably 5000 but to long ago to remember) in boiling distilled water and it passed. It stressed cracked the very first time someone thought to test it with an egg in the water. They aborted before launch, but not before ordering an FCL of SMA.

A real lesson on the value of real world vs lab environment testing.

I never saw data at over 100 deg C, but hydrolysis resistance at 100 deg C (in distilled water) was said to be good.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[ramiroe]

Thanks for the info, both of you. I'm following up on it and waiting for replies. I'll let you know what we (my customer and I) decide to go with.
Thanks again!

 

[Pud]

You will be lucky to get anything cheaper than PC. (I thought PC was usually gamma sterilized? Most medical grades have a purple tint to offset the yellowing when irradiated)

As stated above, plenty of clear stuff - most +$$$$'s comparatively.

http://www.tynevalleyplastics.co.uk

 

[patprimmer]

Re PC

It depends on how many times you wish to autoclave it. PC has a fairly short life in water at 120 deg C due to hydrolysis. Actual life varies greatly depending on grade and stress levels.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[ramiroe]

Well the best material ended up simply being PC. Even the regular blend of PC does have a limited number of times you can autoclave it, not sure how many. There is a higher temp / water resistant blend, but it's not worth the increased cost for us. The other plastics I looked at were either not cheaper or aren't really autoclaveable.
Thanks for the info in any case.

 

[Demon3]

Did you try the high temperature SAN I suggested? It's way cheaper than PC.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[patprimmer]

The number of times PC can be autoclaved in the real world often falls well short of claims in literature and data sheets as it is quite dependant on conditions of test, like stress in the moulding and pH and impurities in the water like chlorine and fluorine and salts.

I know for a fact that the Bayer hydrolysis resistant grade has about twice the life of standard grades from tests done on "unbreakable" beer glasses and Jugs or pitchers. I have data somewhere if that helps.

Also easy flow and mould release grades lose quite a bit of hydrolysis resistance.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules