Plastic that can withstand boiling - 200 cycles 1

[reyemka]

I'm looking for a plastic that can withstand 200 boiling cycles (15min each). It also needs to hold a colour and be high gloss (think consumer medical product).

I've tried high heat ABS with a DTUL above 100°C, but apparently HH ABS is only good in a dry heat. I'm looking for something similar to ABS that can withstand boiling.

It doesn't need to be autoclavable if that helps.

Thanks,

Adam

 

[btrueblood]

PEEK.

 

[reyemka]

Thanks for the reply.

I would also like to ask if anyone has been successful using high heat ABS for applications that require boiling?

 

[patprimmer]

Polypropylene just maybe with no load or stress. It is the material of choice for electric kettles.

TPX if you can get it.

Styrene Malec Anhydride.

Modified PPO maybe.

Regards
Pat
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[dgallup]

Dupont Zytel HTN series. I believe HTN54 in particular retains good properties with moisture up to 110C.

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[patprimmer]

I guess radiator header tank grade 35% glass fibre reinforced special hydrolysis resistant grade nylon 6.6 should also work as they seem to last a few hundred thousand miles at around 100 deg C and up yo 130 deg C I think. It has to equal a few thousand hours.

Regards
Pat
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[Pud]

The problem with the high temp stuff above will be colouring the stuff, and $$$!

My initial suggestion would be to have a look at SAN (Styrene Acrylonitrile) - it's used a lot for reusable kitchenware, it's pretty cheap, colours well, has high gloss and a piece of cake to mould. I would suspect that there are also medically approved grades made by someone. (Well, I know there are...)

Cheers

H

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[Pud]

Another option would be metallocene catalysed polypropylene - can be much stiffer than the usual stuff.

H

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[reyemka]

Pud,

My experience with SAN is that it is very brittle and won't pass a drop test. Can it be modified for impact?

 

[Pud]

If it's moulded correctly (i.e. hot tool, etc), with low residual stress it's pretty good. I would suspect a trawl through data sheets/call to suppliers will reveal an impact modified/toughened grade.

Cheers

H

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[patprimmer]

Opps

By my last post I forgot the medical/gloss thing.

Hydrolysis resistant nylon won't do.

I'm still inclined toward PP. It works in electric kettles.

Regards
Pat
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[reyemka]

Pat, is a glossy finish possible with a filled PP? The increased stiffness is necessary for the design.

 

[patprimmer]

It depends on the filler, but it is possible to get reasonable gloss with some grades, but PP is not my real area of expertise. I have seen high gloss with 50% GF nylon so I know the seeming impossible can be done.

Regards
Pat
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[btrueblood]

I thought PPO only came in brown or black?

 

[Pud]

Ben, I think you are thinking of PPS (also available in an off white).

H

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[Pud]

Long fibre filled PP can have quite a good finish (less ends/weight of glass), but nothing like an unfilled material.

Check out the metallocene PP's - some have quite high stiffness and low warpage compared to usual stuff.

H

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[patprimmer]

I know one trick to improve finish on talk filled PP is to dry it. I know PP does not need drying, but the filler often does. Also some preheat of the granules never hurts a material with good resistance to oxidation. But again, at least from the info provided so far, the stiffest grades unfilled PP should be OK.

Also you say medical, but give no information as to human contact involved For all we know it could be the door knob on the door in a doctors office. OK a stretch, but really we are guessing a lot here.

Regards
Pat
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[reyemka]

Pat, it is a hand held medical device with oral human contact.

Could anyone comment on the feasibility of using PBT or POM? On paper they look good, but there must be disadvantages to both, I'm just not sure what they are.

Thanks for all the ideas!

 

[patprimmer]

They both have really poor resistance to hydrolysis with fairly short life at over 80 deg C.

Same deal for polycarbonate. Hydrolysis resistant grades of PC are used for beer glasses in hotels where the patrons can't be trusted to not break them and use the broken glass as a weapon. They have a fairly limited life due to dishwashing, but it still exceeds the life of glass lost to breakage in rough hotels.

Regards
Pat
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[waynethepain]

Hi Reyemka,

I used to design kettles for a living

On life test (1000's of cycles) PP is the by far the clear winner, try for yourself buy a PP kettle and hold the button down.

And it is cheap!!! PP does have a bad name but when it is designed and moulded correctly the end results are fantastic, but remember it does expand when hot so design accordingly.

Cheers,
Wayne.