Gas Permeable PDMS Membranes
PDMS Membranes are thin (from 20 microns), gas permeable films for use in applications where gases need to be released for pressure or testing purposes, while keeping liquids and solids in situ.
PDMS Membrane applications include gas separation processes, laboratory experiments and medical research that requires a gas permeable and liquid impermeable thin film membrane. Gas permeable PDMS membranes are ultra thin polydimethylsiloxane, silicone or PDMS film products which can be used as a barrier to liquid and permeable path for various gaseous elements and compounds.
The PDMS membranes Limitless Shielding supplies are BFR, 1935/2004, FDA CFR 177.2600 and USP Class VI compliant. The PDMS Membranes are odour free, and produced using a platinum cure catalyst system meaning no hazardous by products or contaminants.
Limitless Shielding’s PDMS Membranes are available in sheets or rolls from as thin as 0.02mm(20µm) to 3.2mm thick. Sheets are 250mm (10″) square. Rolls are 250mm (10″) wide and up to 40m (130ft) long on a roll. Both sheets and rolls come on a thin release liner. The membrane shows a maximum thickness variation across the total width less than ±5%.
Gas Permeable PDMS Membranes can be modified to produce thin film parts, or combined with many other materials to produce composite materials specific to your requirements. We can cut the PDMS Membranes to shape and size according to your application.
For many common gases, PDMS is 30 times more stable than non-silicone polymer materials. In general, applications include gas analysis, detection, enrichment, separation and supporting cell growth.
Available in 20µm, 50µm, 100µm, 200µm, 250µm, 300µm, 400µm, 500µm, 600µm, 800µm, 1000µm, 1500µm, 2000µm, 2500µm and 3200µm Thicknesses
PDMS Membranes are available in transparent and translucent finishes, to suit your required application.
PDMS tube is also available from 1.5mmOD x 0.5mmID up to 31mmOD x 25mmID.
Technical Information
| Property | Condition | Value | Method |
|---|---|---|---|
| Dielectric strength | - | 80 - 100 kV/mm | - |
| Volume resistivity | - | 10¹⁴ Ohmcm | IEC 60093 |
| Hardness Shore A | - | 27° | DIN ISO 48-4 |
| Tensile strength | - | 6.0 N/mm² | ISO 37 type 1 |
| Elongation at break | - | 450 % | ISO 37 type 1 |
| Compression Set | 22 h | 100 °C | 5 % | DIN ISO 815-1 type B method A |
| Gas permeability (selectively) | - | CO₂/N₂ = 10:1 | DIN 53536 |
| Water vapour permeability | 24 h | 20 µm | 3000 g/m² | JIS 1099 A1 |
| Water vapour permeability | 24 h | 50 µm | 1200 g/m² | JIS 1099 A1 |
| Water vapour permeability | 24 h | 100 µm | 800 g/m² | JIS 1099 A1 |
| Glass transition temperature | - | -126 °C | - |
| Operating temperature | - | -45 - 150 °C | - |
| Tear strength | - | 10 N/mm | ASTM D 624 B |
Silicone, chemically known as polydimethylsiloxane (PDMS), is among the most gas permeable dense polymeric membrane materials available. Gases permeate silicone by a solution / diffusion mechanism, whereby the rate of gas permeation is directly proportional to the product of solubility of the gas, and the rate of diffusion of the dissolved gas in silicone. The permeability coefficient is a parameter defined as the transport flux of a gas (rate of gas permeation per unit area), per unit transmembrane driving force, per unit membrane thickness. The permeability coefficient for various gases and vapours in silicone is presented in the table below.
| GAS NAME | FORMULA | PERMEABILITY COEFFICIENT (Barrer)* | GAS NAME | FORMULA | PERMEABILITY COEFFICIENT (Barrer)* |
|---|---|---|---|---|---|
| Nitrogen | N2 | 280 | Ammonia | NH3 | 5900 |
| Carbon monoxide | CO | 340 | Nitrogen dioxide | NO2 | 7500 |
| Oxygen | O2 | 600 | Octane | n-C8H18 | 8600 |
| Nitric oxide | NO | 600 | Butane | n-C4H10 | 9000 |
| Argon | Ar | 600 | Toluene | C7H8 | 9130 |
| Hydrogen | H2 | 650 | Hexane | n-C6H14 | 9400 |
| Helium | He | 350 | Hydrogen sulfide | H2S | 10000 |
| Methane | CH4 | 950 | Benzene | C6H6 | 10800 |
| Ethylene | C2H4 | 1350 | Methanol | CH3OH | 13900 |
| Ethane | C2H6 | 2500 | Sulfur dioxide | SO2 | 15000 |
| Carbon dioxide | CO2 | 3250 | Pentane | n-C5H12 | 20000 |
| Propane | C3H8 | 4100 | Water | H2O | 36000 |
| Nitrous oxide | N2O | 4350 | Carbon disulfide | CS2 | 90000 |
| Acetone | C3H6O | 5860 | |||
| *1 Barrer = 10-10cm3(STP).cm/cm2.s.cm-Hg |
Therefore, the rate of gas transfer across the membrane is proportional to the gas permeability coefficient, the membrane surface area, the trans-membrane gas partial pressure difference, and inversely proportional to the membrane thickness. Thus gas transfer across a membrane increases with increased gas permeability coefficient, increased surface area, increased transmembrane gas partial pressure and decreased membrane thickness.
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