PrePack Oxygen Permeability Analysis in different Temperature & Humidity

Abstract: temperature and humidity are important factors affecting the barrier properties of packaging materials. In this paper, the oxygen permeability of the black-and-white film samples used by PrePack under different temperature and humidity conditions was measured, and the influence of temperature and humidity on the sample barrier was analyzed. Through the description of the test principle, equipment parameters, scope of application, test process and other contents, this paper provides a reference for monitoring the oxygen barrier performance of packaging materials.

Keywords: temperature, humidity, oxygen transmission, oxygen barrier, oxygen transmission test system, coulometer method, equal pressure method, black and white film, PrePack

The barrier performance of packaging materials is affected by many factors, such as material properties and external environment. The performance factors of the material itself include material structure, crystallinity, defect, free volume, interaction between material molecules and gas molecules, etc. the external environmental mainly refer to the temperature and humidity of the environment in which the material is located. According to the actual situation of the product circulation environment, it is of great significance to select the appropriate packaging materials to prevent the product from mildew, oxidation and other problems. Therefore, it is necessary to analyze and study the influence of temperature and humidity on the material barrier performance.

2、Test sample

In this test, the black-and-white film used in the common packaging of liquid food – PrePack bag was used as the test sample to test the oxygen permeability of the sample under different test conditions.

3、Standard

The test methods for oxygen permeability of soft plastic packaging materials include differential pressure method, equal pressure method (coulometric method), etc. this test is based on the coulometric method to test the samples. The test process refers to the method standard ASTM D3985 Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor.

4、Instrument

In this paper, C230 Oxygen Transmission Rate Test System is used. The isntrument is independently developed and produced by Jinan Labthink Instruments Co., Ltd.

4.1 Principle

The principle of equal pressure method is also called coulometric method. The former is named on the basis that the pressure on both sides of the sample is kept equal during the test, and the latter is named because the oxygen content in carrier gas is measured by Coulomb sensor during the test. The test chamber of the instrument is divided into two chambers: the upper chamber and the lower chamber. During the test, the upper chamber is filled with oxygen with a certain pressure, and the lower chamber is filled with high-purity nitrogen with the same pressure as the upper chamber. Under the effect of concentration difference, oxygen penetrates through the sample from the upper chamber to the lower chamber. The nitrogen in the lower chamber carries oxygen to the sensor. Oxygen participates in electrochemical reaction at the coulometric sensor. According to the monitored result of quantitative relationship between the electric signal and oxygen, the amount of oxygen permeating through the sample per unit area in unit time can be calculated.

Figure 1 C230H Oxygen Transmission Rate Test System

5、Test procedure

In order to compare the effect of temperature and humidity on the barrier property of the sample, the oxygen permeability of the sample was measured at 23 ℃, 0% RH, 23 ℃, 60% RH, 30 ℃ and 0% RH. The test process is as follows:

(1) Cut 3 specimens from the sample and clamp them in three test chambers of the instrument.

(2) Set the specimen name, thickness, test mode, test temperature, humidity and other parameters in the control software, click the “test” button to start the test, the instrument runs according to the set parameters, and displays the results after the test.

(3) Change the test temperature and humidity conditions, and test the oxygen permeability of the sample under three test conditions in turn.

6、Test results

See Table 1 for the test results of oxygen permeability of samples under three test conditions

Table 1 Oxygen Transmission Rate Test Results

Test conditions	23℃、0%RH	23℃、60%RH	30℃、0%RH
OTR cm3/(m2·day)	8.056	8.794	11.637

7、Conclusion

Compared with the oxygen transmission rate at 23℃、0% RH, the oxygen transmission rate at 23 ℃ 60% RH and at 30 ℃ 0% RH is increased, especially the oxygen transmission rate at 30 ℃ 0% RH had a more prominent increase, indicating that as the temperature and humidity increase, the barrier properties of the tested samples decrease, and the temperature had a greater impact on the oxygen permeability of the samples. Regarding the test process, the operation is simple, efficiency is high, and the test conditions such as temperature and humidity is stable during the test, the test results are therefore reliable.