I need to make polyethylene film that allows gas to pass through it under pressure of 10-20 psi, albeit at a very slow rate.
Is there in any fillers or some way of formulating the polyethylene so that it maintains a barrier to water, but allows air/gas molecule to escape over time. The idea is to prevent pressure build-up due accumulation of gas in a confined space.
Thank you.
Polyolefins are considered as one of the most permeable thermoplastics for gases and possess relatively much higher gas transmission rates compared to other polymers such as polyesters, polyamides etc. On the other hand, they show excellent barrier performance against water and water vapour. Regarding your question, several approaches could be tried to overcome the problem depending on the long-term performance prospects for the films.
Please search out the "breathable films". It is a well-known and simple technology; including compound preparation by introducing inorganic fillers into polyethylene matrix then film processing and controlled streching the film to create highly permeable holes/voids at polymer-filler interface. Another solution could be polymer-polymer blending. Second one is a more versatile way than the compounding with fillers. I could suggest some more in detail if you get in contact with me.
Good Luck.
Sear Dilip,
Polyolefins are well known the breathable materials. Also, they can breath slowly. A film have to get over the 10-20psi ( it means 0,7- 1,4 bar). In this point, you may need to have the very thick film, but if you increase the thickness, the breathable property goes to decreasing. I think the EVA based films are the most suitable material for your need.
But if you need a material, it breathes properly. I advice to you, you should make a film it has tubular nano filler. Thus, the film breathe simply.
Good Luck.
Hi Deniz,
Thank you so much for taking time to answer my question.
I am looking at vapor or gas transmission through the polyethylene film at 1- 3 psi, with flow rate in the range of 100 -300 ml/min.
So that's quite a jump from the normal PE permeability rates.
It's almost getting in a semi-foam state to arrive at those rates.
But I do not want to foam, its the last resort.
I was hoping to find a a solution by way of fillers and/or polymer blends that could help with this.
I think it's a long shot, but never ventured, never gained...lol
I like your idea of the tubular nano fillers.
Can you share any papers/references that you might have on this.
Thanks
Dilip
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