Why does the rubber have to do the moist heat ageing test The moisture and heat to the rubber ages the destruction primarily to express in the water vapor infiltrate rubber and the heat accelerates this kind of infiltration. With the different types and formulations of rubber, there are different mechanisms in the aging process. In general, humidity will have the following effects on rubber: the expansion of the rubber sample will increase the gap between molecular chains, expose more molecular weak bonds, increase the stress of the molecular chain, and make the compounding agent in the rubber easy to diffuse and lose. Promoting the release of hydrogen halides from halogen-containing chains; catalytic activation of metamorphic metals; and hydrolysis of chains containing ester, ether, and amide groups. Humidity also accelerates the oxidation of ozone.
The hygrothermal aging test is an artificial accelerated aging test used to identify or study the aging resistance of polymer materials. It can also be used to study the storage period and service life of certain polymer materials. It exposes the test sample to a humid hot air environment, undergoes the action of hot air and water vapor, and measures the change in properties of the sample at a predetermined time, thereby assessing the resistance to moisture and heat aging of the rubber. Hygrothermal aging test conditions must be determined based on material properties, conditions of use, and test objectives.
When used or stored indoors, rubber has a significant effect on relative humidity in addition to temperature. From some data, it is prone to hydrolysis of rubber such as silicone rubber, urethane rubber, chlorohydrin rubber, acrylate rubber and so on. The hygrothermal aging test is closer to the actual situation than the data derived from the hot air aging test. These rubbers are sensitive to the effects of heat and humidity. They are prone to aging and deterioration under the influence of heat and humidity, and humidity has a significant acceleration effect on the aging of these rubbers. Therefore, the hygrothermal aging test has received increasing attention from people.
The hygrothermal aging test can more accurately reflect the dual effects of moisture and heat on rubber aging. For some humidity-sensitive materials, it is undoubtedly a more accurate experimental research method. The main problem existing in the hygrothermal aging test is that the reproducibility of the test results is poor, mainly due to fluctuations in relative humidity, sample preparation, and specific test operation methods. Therefore, during the test, the relative humidity and the process conditions for sample preparation should be strictly controlled. The test can comply with the relevant national standards such as GB/T 1590 “Vulcanized Rubber Hygrothermal Aging Test Methodâ€.
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