Cellophane / Cellulose forms other than film

[MMcCawley]

Hello,

I'm considering using Cellophane in an application to reduce CO2 permeability in a pressurized container. Can anyone tell me if cellophane can be formed into any shapes other than film? I.E. can it be used as a coating, extruded, injection molded, etc?

Thanks for your time!

 

[Compositepro]

Cellophane is produced by drying a solvent from a solution. I don't think it is made in the US any longer because of the cost of environmental compliance issues which don't exist in some other parts of the world. You can find what you are looking for using Google. I don't think it would be a good barrier to CO2 since it is often used for its high permeability.

 

[Demon3]

Cellophane in the US is often used as a generic term for plastic wrap, like the kind used to wrap food. Actual Cellophane is made of cellulose film but "plastic wrap" can be many polymers such as PVC, PVDC and LDPE.

http://en.wikipedia.org/wiki/Plastic_wrap

As each is a different polymer, it's permeability to CO2 will be different. In some cases very different.

So, first we have to determine which polymer is under discussion then look for some specific data. There are books on this topic. The most comprehensive one I know of is:

Permeability Properties of Plastics and Elastomers, 2nd Ed., Second Edition: A Guide to Packaging and Barrier Materials

http://www.amazon.com/Permeability-Properties-Plastics-Elastomers-Edition/dp/1884207979

As far as forming goes, there are moldable types of cellulose such as cellulose acetate propionate from Eastman. It can be injection molded and thermoformed for example. The other polymers mentioned can too. You can dramatically improve the barrier by adding a platy mineral such as high aspect ratio mica.

Dr. Chris DeArmitt

Plastics consultant to the Fortune 500:

http://www.phantomplastics.com

Webinars on plastics, fillers & impact modification:

http://www.plastictraining.com

 

[MMcCawley]

Hi Chris,

I've got a copy of a similar paper (same name but written by Laurence McKeen) which is what originally lead me down the Cellophane path. And yes, I am referencing Cellophane and not a generic "Plastic Wrap". From a CO2 permeability perspective Cellophane is far superior than any other material I've come across thus far (.309 cm^3 mm / m^2 day atm vs 2.51 and 3 for Kel-F and Parylene C respectively).

Thank you for the Cellulose Acetate Propionate suggestion, I'll look into it. Offhand, can I expect similar permeability performance compared to pure Cellophane?

Thanks again for your help,
Matt

 

[Demon3]

Cellulose itself can't be melted and molded so I'd probably look in that book or do net searches to find the formable plastic with the best barrier to CO2. Liquid crystalline polymers like Vectra are normally very good.

Dr. Chris DeArmitt

Plastics consultant to the Fortune 500:

http://www.phantomplastics.com

Webinars on plastics, fillers & impact modification:

http://www.plastictraining.com

 

[Compositepro]

Plastic films that require very low gas permeabilty are usually metalized.

 

[MMcCawley]

Thank you guys. I've done a little research and still have a ways to go but it looks as though there may be a few barrier coatings which will enable me to achieve my desired results (Ethylene vinyl alcohol- EVOH being one of them). Here is a link to a great paper I've found on Barrier Polymers:

http://aspeak.net/\Upload\subdomain\aspeak\article\aspeak1391-11-7-10-10-50Barrier_Polymers (

http://www.aspeak.net).pdf