Dear colleagues:
I would like to know which plastic (or other material) fabric best meets a double objective: high O2 permeability and low water permeability. My idea is to design a bag or box for vermicomposting or hot-composting systems that will outperform the existing ones. In the case of worms, bags are made of polyester and nylon. In hot composters, the boxes are usually made of polypropylene, but I was wondering if there would be better rigid or flexible materials to make better composters.
Thanks
D
Thanks Kavana but I was referring to a plastic that allows oxygen to pass through but not water. I looked at this product and it is a gas barrier.
some of the plastics that have the best permeability to oxygen and the lowest permeability to water are:
- Polyethene terephthalate (PET): PET is a common plastic used for beverage bottles, food containers and packaging. It has a low oxygen transmission rate (OTR) of about 0.1-0.3 cm3/m2/day/atm and a low water vapour transmission rate (WVTR) of about 1-2 g/m2/day at 23°C and 50% relative humidity.
- Polyvinylidene chloride (PVDC): PVDC is a plastic that is often used as a coating or a layer in multilayer films or laminates. It has a very low OTR of about 0.01-0.03 cm3/m2/day/atm and a very low WVTR of about 0.1-0.3 g/m2/day at 23°C and 50% relative humidity.
- Ethylene vinyl alcohol (EVOH): EVOH is another plastic that is often used as a barrier layer in multilayer films or laminates. It has a low OTR of about 0.05-0.15 cm3/m2/day/atm and a low WVTR of about 0.5-1.5 g/m2/day at 23°C and 50% relative humidity.
These plastics have better permeability to oxygen and lower permeability to water than other common plastics such as polyethene (PE), polypropylene (PP), polystyrene (PS) or polyvinyl chloride (PVC). However, the permeability of plastics can vary depending on their thickness, density, crystallinity, orientation, additives, temperature, humidity and other factors. Therefore, it is important to test the actual permeability of the plastic material under the specific conditions of use.
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