Cling film is a plastic packaging product used by people to preserve food. It can be used to heat food in a microwave and store it in a refrigerator, so it is required to have high oxygen permeability. The main testing methods for oxygen permeability of flexible plastic packaging materials in China are differential pressure and coulometric method (i.e. isobaric method), with reference to the following method standards:GB/T 1038Test method for gas permeability of plastic films and sheets - Differential pressure methodGB/T 19789The Coulombic method for testing the oxidation permeability of plastic films and sheets in packaging materials. This article tests based on the principle of differential pressure method, with reference to the standardGB/T 1038.

Here, we use a certain brand'sPETaking plastic wrap as an example, useSai Cheng InstrumentDeveloped and producedGPT-203Differential pressure method gas permeameterPEOxygen permeability test of cling film.

GPT-203The pressure difference method gas permeability tester is based on the testing principle of the pressure difference method and is a professional gas permeability tester for thin film samples. It is suitable for measuring the gas permeability, solubility coefficient, diffusion coefficient, and permeability coefficient of plastic films, composite films, high barrier materials, sheets, and metal foils at various temperatures.

GPT-203Differential pressure gas permeameter

Testing principle:GPT-203Using the principle of differential pressure testing, the pre processed sample is placed between the upper and lower testing chambers and clamped. Firstly, perform vacuum treatment on the low-pressure chamber (lower chamber), and then evacuate the entire system; After reaching the specified vacuum degree, close the lower chamber of the test, fill the high-pressure chamber (upper chamber) with a certain pressure of test gas, and ensure that a constant pressure difference (adjustable) is formed on both sides of the sample; In this way, gas will permeate from the high-pressure side to the low-pressure side under the action of pressure gradient. By monitoring and processing the pressure inside the low-pressure side, various barrier parameters of the tested sample can be obtained.

The experimental process is roughly as follows:

(1)Cut the size with a samplerΦ97 mmsample3The film.

(2)Translate into English3The sample pieces are clamped separately in the equipment3On a testing chamber.

(3)Set parameters such as sample name, sample thickness, test temperature, and test humidity.

(4)Start the vacuum pump.

(5)click“Start the experiment”Option: The experiment begins and the instrument automatically calculates and displays the test results.

Experimental results: The oxygen permeation rates in this test were as follows:49.3704 cm3/m2·24h·0.1MPa，48.1021 cm3/m2·24h·0.1MPa，48.2883 cm3/m2·24h·0.1MPa.

VAC-V2Technical specifications of pressure difference gas permeameter:

Test scope:0.05～50,000 cm3/m2·24h·0.1MPa(Conventional)

The upper limit is not less than500,000 cm3/m2·24h·0.1MPa(Expand Volume)

Number of samples:3 Items (data independent of each other)

Vacuum resolution:0.1 Pa

Test chamber vacuum degree: ＜20 Pa

Temperature control range:5℃～95℃

Temperature control accuracy:±0.1℃

Moisture control range:0%RHThe2%RH～98.5%RHThe100%RH(Humidity generating device to be purchased separately)

Humidity control accuracy:±1%RH

Sample size:Φ97 mm

Through area:38.48 cm2

Test gas:O2TheN2TheCO2Waiting for gas (gas source to be provided by the user)

Test pressure:-0.1 MPa～+0.1 MPa(Conventional)

Gas source pressure:0.4 MPa～0.6 MPa

Interface size:Ф6 mmPolyurethane pipe

Overall dimensions:760mm(L) × 575mm(W) × 450mm(H)

power supply220VAC 50Hz / 120VAC 60Hz