Tyres are the main carriers of car loads. The airtightness of tires has a more or less influence on the overall performance of the car. A tire with good airtightness can improve the safety, driving performance and comfort of the car. Can reduce the tire rolling resistance, thereby reducing the fuel consumption; due to lower fuel consumption, thereby reducing the carbon dioxide emissions; can reduce the number of tire inflation, easy maintenance of the car. The tire has the most appropriate shape when it is held in the tire with proper air pressure, and various properties are fully utilized according to the designed performance requirements. Therefore, the air tightness of the inner liner is very important for the car.
Test basis:
The airtightness of the tire innerliner can be tested according to GB/T 7755-2003 Determination of Vapor Permeability of Vulcanized Rubber or Thermoplastic Rubber . This standard gives a method for testing the hermeticity of rubber materials, which can be quickly and accurately. The resistance to air permeability of the rubber was examined, which provided a reliable basis for the choice of materials for the manufacture of the tire.
Test principle:
Using the differential pressure test principle, the pre-treated sample is placed between the upper and lower test chambers. First, the low pressure chamber is vacuum treated, and then the entire system is evacuated; when the specified vacuum degree is reached, the lower chamber of the test is closed, a test gas of a certain pressure is filled into the high pressure chamber, and a constant pressure is ensured on both sides of the sample. Differential pressure; due to the presence of differential pressure gradients, the gas penetrates from the high pressure side to the low pressure side. By monitoring and processing the low pressure side internal pressure, the barrier property of the tested sample can be obtained.
Sample selection:
The diffusion degree and velocity of gas in the polymer are related to the molecular thermal motion of the polymer. The side methyl groups in the butyl rubber molecular chain are densely distributed, which limits the thermal motion of the polymer molecules. Therefore, butyl rubber has good air permeability resistance and is a commonly used material for tire inner tubes or inner liners. This article takes the test of butyl rubber as an example to introduce the testing method for the airtightness of tire inner tubes.
Specimens with flat, no scratches, no perforations, or other defects were selected for the sample.
equipment:
The VAC-V2 differential pressure method gas permeability meter independently developed by Jinan Languang Electromechanical Technology Co., Ltd. is based on the differential pressure test principle and is a professional instrument for gas permeability test. The three test chambers of this instrument are completely independent. Three kinds of same or different samples can be tested at the same time. The test accuracy is high. The test temperature can be controlled from 5 °C to 95 °C with an accuracy of ±0.1 °C . The humidity control range is 0%RH , 2%RH ~98.5%RH , 100%RH , and the humidity control accuracy is ±1%RH , which can accurately test the gas permeability of high barrier materials.
Fig. 1 VAC-V2 Differential Pressure Gas Permeameter
Test conditions:
Temperature 23 °C , dry air.
Test steps:
Use a special sampler to cut three specimens.
Figure 2 sample
Clean the dust on the surface of the lower chamber with a soft material, apply a vacuum grease evenly in the sealing area of ​​the lower chamber, place the cut filter paper on the low pressure side to support the specimen, and prevent the vacuum grease from entering the low pressure chamber. , place the sample.
Figure 3 placed the sample
Cover the upper chamber, set the test parameters, and start the test.
After testing, the air permeability of this sample is as follows:
Sample name
Thickness ( μm )
Test result cm3/(m2·24h·0.1MPa)
1#
2100
17.189
2#
2100
15.903
3#
2100
16.267
Conclusion:
The use of VAC-V2 Differential Pressure Gas Permeability Tester can accurately measure the gas permeability of automotive tire rubber and better reflect the airtight properties of automotive tires. In recent years, Jinan Languang Electromechanical Technology Co., Ltd. has provided countless times of rubber gas permeability testing services for customers around the world, including various types of automotive inner tubes and rubber products from various companies at home and abroad. Labthink looks forward to working with companies in the industry. Units increase technical exchanges and cooperation. For more information about related instruments, you can visit the website of Jinan Languang Company to check specific information or call for advice.
Copyright Notice: This article is copyrighted by Jinan Languang Electromechanical Technology Co., Ltd.
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