Reference number
ISO 6796:1981
ISO 6796:1981
© ISO 2024
International Standard
ISO 6796:1981
Polyglycols for industrial use — Determination of hydroxyl number — Phthalic anhydride esterification method
Edition 1
1981-09
1981-09
ISO 6796:1981
13294
Published
(Edition 1, 1981)
This publication was last reviewed and confirmed in 2019.
Therefore this version remains current.
Abstract
The hydroxy groups present in a test portion are esterified with phthalic anhydride. The excess phthalic anhydrids is hydrolyzed and the phthalic acid formed is neutralized with standard volumetric sodium hydroxide solution. If the sample contains free acidity or alkalinity a corresponding correction is made. From the corrected hydroxyl number, the apparat relative molecular mass may be calculated by a formula given.