The core of oxygen permeability testing for aluminum foil paper is to use differential pressure method or isobaric method to accurately quantify the oxygen permeability per unit area and unit time. The core standards refer to GB/T 1038 and ASTM D1434. SYSTEST Jinan Sike will introduce the oxygen permeability testing method for aluminum foil paper.

Test principle selection

Differential pressure method: suitable for high barrier pure aluminum foil. After vacuuming both sides of the sample, pure oxygen is introduced into one side, and the oxygen permeation rate is calculated through pressure changes on the other side.

Isostatic pressure method (Coulomb meter method): suitable for aluminum foil composite film, with oxygen gas on one side of the sample and a carrier gas (nitrogen gas) on the other side. The oxygen gas that passes through is mixed with the carrier gas and detected by a Coulomb meter, resulting in higher accuracy.

Core testing conditions

Temperature: Normally controlled at 23 ℃ (standard environment), special requirements can simulate high temperature scenarios such as 50 ℃.

Humidity: Set according to the purpose, such as dry conditions (0% RH), simulated storage environment (50% or 85% RH).

Sample preparation: Cut 100-200 cm ² samples without pinholes or creases, prepare at least 3 parallel samples, and distinguish the orientation of the inner and outer layers of the composite aluminum foil.

Preprocessing: The sample is equilibrated in the testing environment for 24 hours to eliminate the influence of environmental differences on the results.

Test steps

Installation sample: Fix the cut aluminum foil between the test chambers to ensure a seal without leakage.

Environmental calibration: Start the equipment and stabilize the temperature, humidity, and vacuum degree (pressure difference method) or gas concentration (isobaric method).

Test run: Set the test time (usually 24 hours, high barrier samples can be extended to 72 hours) and record real-time transmission data.

Result calculation: Take the average value of the flat sample, expressed in cm ³/(m ² · 24h · atm), and label the pure aluminum foil result as "<0.01" (below the detection limit).

Precautions

Before testing, it is necessary to check the sealing of the equipment to avoid air leakage that may cause high results.

The pinholes in pure aluminum foil will significantly affect the data, and it is necessary to screen for defect free samples through microscopic pretreatment.

Composite aluminum foil needs to have a clear composite structure (such as PET/aluminum foil/PE), and test results for different structures need to be recorded separately.