Source: Link Testing Instruments Co.,Ltd.
The pendulum impact energy of the film is a physical quantity that measures its impact resistance. Generally speaking, the higher the pendulum impact energy, the better the impact resistance and flexibility of the film. After the film is used for packaging products, it will inevitably be impacted by external forces during the later transportation and storage. If the impact resistance of the film is poor, it is easy to break the bag under such impact or impact, so it has good resistance. Impact performance is one of the necessary properties of film materials.
The pendulum impact resistance of the film is generally tested by a film impact tester, which detects the energy value consumed when the punch breaks through the sample. Generally speaking, a punch with a smaller diameter has a smaller contact area with the film when it impacts the film, while a punch with a larger diameter has a larger contact area with the film. In theory, this difference in contact area leads to breaking the sample In order to verify this conclusion, this paper uses punches of different diameters to test the pendulum impact energy of the film.
Test method and instrument
At present, the testing standard for pendulum impact energy of film materials is GB 8809-1988 "Plastic Film Anti-Pendulum Impact Test Method".
The test equipment used to test the pendulum impact energy of the samples in this paper is the Auto Pendulum Impact Tester LTJM-06 independently developed and produced by Link Testing Instruments Co.,Ltd.
Test principle: The basic test principle of this test is conservation of energy, and the energy consumed by resistance such as air during the test is ignored. During the test, the pendulum is released from a certain height, so that the punch breaks through the sample at a certain speed, and continues to move up to a certain height before falling back. By testing the energy change of the punch before and after breaking the sample, the anti-pendulum impact energy of the sample is obtained.
Test sample and test process
Test sample: The test sample used in this test is a single-layer polyethylene (PE) film material for packaging.
Experimental procedure:
(1) Randomly cut 20 specimens of 10 cm × 10 cm along the width direction of the sample roll film surface, and place the specimens at a temperature of 23±2 ℃ and 45% ~ 55% RH for at least 4 hours. , And experiment in this environment.
(2) Use a thickness gauge to test the thickness of the sample, test 10 points, and take the arithmetic average of the 10 points.
(3) A punch with a diameter of 12.7 mm is selected for the test, and the jaw diameter of the sample is all selected as 89 mm.
(4) Perform equipment calibration according to equipment requirements.Clamp the sample flatly into the sample holder of the equipment, and the sample should not have wrinkles or excessive tension.
(6) Enter the test interface, fix the pendulum, click the test button, the pendulum will automatically fall, impact the sample, the device displays the anti-pendulum impact energy of the sample.
(7) Conduct the pendulum impact energy test on 10 randomly selected samples in sequence.Change to a punch with a diameter of 19 mm, and test the pendulum impact energy of the remaining 10 specimens according to the steps (4) ~ (7).
Test results and analysis
The thickness of the sample is 79.6 μm. When a punch with a diameter of 12.7 mm is used, the average value of the pendulum impact energy of 10 samples is 0.863 J. When a punch with a diameter of 19 mm is used, 10 samples The average value of the impact energy of the pendulum is 1.731 J.
When testing the pendulum impact energy of the film, the corresponding test results of using different diameter punches are quite different, and the test results are incomparable. Therefore, companies are comparing and analyzing packaging materials by testing the pendulum impact energy of the film. When the impact resistance and flexibility of the product, a punch of the same diameter should be used for the test.
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