Coating science: the identification method of epoxy resin

there are no simple proprietary tests for cross-linking units in converted epoxy bases or cured epoxy resinsThe dioxin test for epoxy to phenols is a positive reaction (due to the presence of bpa A)In contrast to phenolic resins, the chromium-acid test for formaldehyde is a negative reactionwhen thermal lysis is performed at less than 260 degrees C, acetaldehyde is produced in all epoxy resinsThe steps are: put the test tube in the hot lysate tube, the tube mouth is covered with a newly formulated 5% sodium nitrocyanide and a quid hydrosol wetting filter paper, heated to 240 degrees C in the oil bathWhen the gas liberated by thermal cracking passes through the filter paperThe blue color of the filter paper indicates that it is epoxy resincan also identify epoxy resin sin by release method: at room temperature, take about 100 mg of resin in about 10 ml of concentrated sulfuric acid, and then add about 1 ml of concentrated nitric acidAfter five minutes, carefully add 5% sodium hydroxide to the top of the solution, and if there is a BPA epoxy, the interface of the two layers of solution will appear cherry red