Jan 7, 2018, 7:40 PM
Post #1 of 1
Hydroxyl value (hydroxyl equivalent): The hydroxyl value means the number of moles of hydroxyl groups contained in 100 g of the epoxy resin. The hydroxyl equivalent refers to the mass of epoxy resin containing 1mol hydroxyl grams. Hydroxyl determination of two ways: First, direct determination of hydroxyl content in the epoxy resin; the second is to open the epoxy group to form a hydroxyl group, and further determination of the sum of the hydroxyl content. The former method is based on lithium aluminum hydride and active hydrogen-containing groups for rapid and quantitative reaction principle, for the direct determination of epoxy resin hydroxyl, is a more reliable method. The latter method is acetic anhydride, pyridine and concentrated sulfuric acid mixture of acetylation reagents and epoxy resin reaction to form a hydroxyl group, and then determine the total hydroxyl content, and then double the epoxy reduced, you can measure the ring The hydroxyl content in the oxygen resin is the hydroxyl number. (3) Esterification equivalent: Esterification equivalent refers to the mass grams of the epoxy resin required to esterify 1 mole of monocarboxylic acid (60 g of acetic acid or 280 g of C18 fatty acid). Epoxy hydroxyl and epoxy groups can be esterified with carboxylic acid. Esterification equivalents may represent the total content of hydroxyl and epoxy groups in the resin.
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