Recently, with 137 participating laboratories receiving the comparison reports, the 2019 Labthink 6th Global Plastic Film Inter Laboratory Comparison was successfully concluded.

This comparison was centered on five test items: oxygen permeability, water vapor permeability, breaking force, elongation and thickness. A total of 137 laboratories from around the world participated, the testing equipment are world-renowned brands including Labthink, MOCCON, SYSTECH-Illinois, Brugger, Instron, MTS, ZWICK, MAHR and many others.

The comparison results are as follow:

From the overall data distribution, the results of barrier test (oxygen permeability, water vapor permeability) are generally discrete and have broader range. It can be seen that there are great differences between different laboratories in the measurement of oxygen permeability and water vapor permeability. In addition, in this comparison, the results of some laboratories obviously deviate from the normal data, indicating that for barrier testing, laboratories should still pay attention to the accuracy of equipment and standardization of operation, make effort on periodic verification of equipment according to requirements, to ensure the correctness of test results.

For the test of breaking force and elongation, the results of some laboratories are on the low side. Excluding the factors of equipment, for most laboratories the problems occur in the sample preparation process, such as the sample preparation operation is not standardized, the table is not flat enough, the cutting knife is not sharp, the sample is skewed, etc. In this comparison, the effect of sample preparation on the test results is obvious. After adjusting the sample preparation operation in some laboratories which had deviated data, their test results have been significantly improved. However, the influencing factors of sample preparation level are complex and difficult to discover, which requires laboratories to control the aspects of personnel training, tool selection, operation experience and so on.

Thickness testing returned good results. Some laboratories are less sensitive to the unit of test results, and didn’t convert the results in the corresponding unit before submission. Laboratories should pay attention to this problem. Because thickness is a basic measurement item, it is often used for calculation in other plastic film physical performance tests. The unit error may lead to magnitude errors in the related physical performance test results.

Thickness testing returned good results. Some laboratories are less sensitive to the unit of test results, and didn’t convert the results in the corresponding unit before submission. Laboratories should pay attention to this problem. Because thickness is a basic measurement item, it is often used for calculation in other plastic film physical performance tests. The unit error may lead to magnitude errors in the related physical performance test results.