Coating Science Popularization: identification method of epoxy resin
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Last Update: 2020-03-05
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Source: Internet
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Author: User
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There is no simple and exclusive test method for the crosslinking units in transformed epoxy or cured epoxy The Gibbs indophenol test of epoxy resin for phenol is a positive reaction (due to the presence of bisphenol A) In contrast to the phenolic resin, the chromic acid test for formaldehyde is a negative reaction When the temperature is lower than 260 ℃, acetaldehyde will be produced in all epoxy resins The steps are as follows: put the test tube into the pyrolysis tube, cover the opening with the filter paper wetted by the newly prepared 5% sodium nitrocyanide and morpholine aqueous solution, and heat it to 240 ℃ in the oil bath When the gas released by thermal cracking passes through the filter paper, the blue color of the filter paper indicates that it is epoxy resin The epoxy resin can also be identified by the following methods: at room temperature, take about 100 mg of resin into about 10 ml of concentrated sulfuric acid, and then add about 1 ml of concentrated nitric acid After five minutes, carefully add 5% sodium hydroxide solution to the top of the solution If there is bisphenol A epoxy resin, the interface of the two solutions will appear cherry red.
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