Scope:

ASTM D3985 test includes a procedure for determining the steady-state transmitting rate of oxygen gas through flexible barrier materials. These materials might be in the form of film, sheets, laminates, co-extrusions, or plastic coated papers or fabrics. In cases of homogenous materials it determines oxygen gas transmission rate (OTR): the permeance of the film to oxygen gas (PO₂) and oxygen permeability coefficient (P′O₂). Material thickness and environmental conditions such as relative humidity and temperature are the main factors for understanding material permeation.

Test Procedure:

The ASTM D3985 test sample is attached to ambient atmospheric pressure as an enclosed half-block between two chambers. ASTM D3985 requires a stream of nitrogen that purges one chamber and oxygen on the other chamber. As oxygen gas is permeated into the film and transferred to the coulometric detector, an electric current is generated in proportion to the amount of oxygen streaming through the detector per unit time. The detector also produces electric power in the film. The test gas is for oxygen and the carrier gas is nitrogen gas. The upper chamber oxygen gas concentration is greater than the lower chamber since some concentration difference is created between the two sides of the sample. Oxygen gas passes from the upper chamber into the lower chamber during the transmission process.

Specimen size:

Specimen with area 50 cm².

Data:

Oxygen Transmission Rate (OTR) mol/(m²s)

Conclusion:

ASTM D3985 is a standard test method that covers a procedure for determination of the steady-state rate of transmission of oxygen gas through plastics in the form of film, sheeting, laminates, co-extrusions, or plastic-coated papers or fabrics.