Polycarbonate? Is this the right plastic to use?

[sunburn731]

I'm looking for a plastic that have these characteristics:

1)Optically clear
2)Chemically resistant (particularly against oil, petroleum based chemicals)
3)Impact resistant / durable
4) Easy to mold

Any recommendations would be helpful. Thank you.

 

[patprimmer]

No

Are you a student.

Regards
Pat
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[simonshall073]

No,PC is not chemical attack rsistant,especially petrol.

The polymer that have all your required characters is: transparent PA12,whose features are as below:

* Clear transparency even in high wall thicknesses
* Good light natural colour 
* Can be coloured in transparent as well as opaque colours
* high toughness at low temperature
* high fatigue strength  
* Excellent chemical(i.e petrol oil)and stress-crack resistance
* High resistance to cooking water
* Ductile breakage, high flexibility


Hope this will help you


Rds
Simon

 

[patprimmer]

Cellulose propionate also meets the above as does some new amorphous PET copolymers and PETG

Regards
Pat
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[sunburn731]

Thanks everyone.

 

[simonshall073]

PAT is right,PET or PETG is OK unless the working tempretaure is not high,peak tempature 60-70 centigrage no problem.

If need to withstand higer than 100 centigrade,PA12 is preferable,it's HDT reach 135 or so.

It's up to your working condition.

Since the material should be optically clear, no filler can be added in order to improve the HDT.


Simon

http://www.golden-plastics.com

 

[patprimmer]

No mention was made of temperature.

Cellulose propionate is reasonably clear.Better than PVC and almost as good as PC.

He still has not replied re student status, so maybe he is cheating on his homework?

135 deg C is very high for unfilled nylon 12 unless you are confusing it with something like Reny or some grades of Grilamid more often described as nylon MDX or aromatic nylons.

Regards
Pat
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[sunburn731]

Haha, I am a student of you guys.

I'm actually an Industrial Designer; having worked primarily in consumer electronics. I'm working on a helmet and needed insight on plastics. I'm unfamiliar outside of plastics like ABS for CE...

I don't think heat will be an issue, but voltage may be. As some safety helmets have a class rating for how much shock it can absorb.

Thanks again guys.

 

[patprimmer]

How clear does a helmet have to be.

Probably PP random co-polymer will do. They have some pretty good transparency now and are used for clear containers in under bonnet (hood) applications.

Regards
Pat
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[sunburn731]

It needs to be as optically clear as possible. Part of the helmet will be used to view out of. I think there will be an acceptable amount of hazyness / cloudiness...but for the most part, perceived quality would be best with something optically clear.

 

[patprimmer]

In my opinion Cellulose Propionate makes the best safety visor material due to its balance of clarity, toughness and resistance to solvent stress crack from common solvents.

Much tougher than acrylic and much more solvent stress crack resistent than PC and about as clear as PC.

Regards
Pat
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[Pud]

Try this:

http://www.ems-group.com/mytools/newssystem/pdfdateien/1042/grilamidtr_e_08.2006.pdf

Probably made by others too.

H

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[patprimmer]

Pud

The Japanese make one called Reny that is pretty similar I think.

I'm not sure who does the old Trogamid now, maybe that is EMS also

Transparent nylons where a lot more expensive than propionate although that may have changed as cellulosics have escalated a quite a bit due to increased environmental control costs.

Regards
Pat
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