The role of defoamers in antioxidants
Some organic compounds that can inhibit or delay the thermal oxidation of polymers and other organic compounds in the air. For example, foods are prone to oxidation and deterioration, and a small amount of antioxidants can be added to extend their storage time. Plastics, synthetic fibers, rubber and other polymer materials are prone to thermal oxidation degradation reactions. Adding antioxidants can maintain the excellent properties of polymer materials, and defoaming agents can extend their service life. The study of the specific surface area of antioxidants is very important. The specific surface area test data of antioxidants can only be true and reliable if they are detected using the BET method. At present, many instruments in China can only perform direct comparison tests, which have now been eliminated in China. At present, the specific surface area test at home and abroad uniformly adopts the multi-point BET method. The specific surface area determination standards formulated at home and abroad are based on the BET test method. Please refer to my country’s national standard (GB/T 19587-2004) – the method for determining the specific surface area of solid substances by the gas adsorption BET principle. Specific surface area testing is actually a time-consuming task. Due to the different adsorption capacities of samples, the testing of some samples may take a whole day. If the testing process is not fully automated, the tester cannot leave at any time and must be highly focused, observing the dashboard and operating the knobs. A little carelessness will lead to the failure of the testing process, which will waste a lot of precious time for the tester. F-Sorb 2400 specific surface area tester is an instrument that can truly realize the BET method detection function (with direct comparison method). More importantly, F-Sorb 2400 specific surface area tester is the only fully automated and intelligent specific surface area detection equipment in China so far. Its test results are highly consistent with international standards and have good stability. At the same time, it reduces human errors and improves the accuracy of test results. The thermal oxidation process of organic compounds is a series of free radical chain reactions. Under the action of heat, light or oxygen, the chemical bonds of organic molecules break to generate active free radicals and hydroperoxides. Hydroperoxides undergo decomposition reactions and also generate hydrocarbon oxygen free radicals and hydroxyl free radicals. These free radicals can trigger a series of free radical chain reactions, leading to fundamental changes in the structure and properties of organic compounds. The role of antioxidants is to eliminate newly generated free radicals, or to promote the decomposition of hydroperoxides to prevent the chain reaction. Antioxidants that can eliminate free radicals include aromatic amines, hindered phenols and their derivatives, which are called primary antioxidants; antioxidants that can decompose hydroperoxides include phosphorus-containing and sulfur-containing organic compounds, which are called auxiliary antioxidants.
