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ASTM D4274-21

Standard Test Methods for Testing Polyurethane Raw Materials: Determination of Hydroxyl Numbers of Polyols

1.1These test methods measure the hydroxyl groups in polyester and polyether polyols containing primary and secondary hydroxyl groups. They also apply to many other hydroxyl-containing substances.

1.1.1Test Method A - Acetic Anhydride Pressure Bottle, recommended for polyesters.

1.1.2Test Method B - Phthalic Anhydride Pressure Bottle, recommended for polyethers and polyesters.

1.1.3Test Method C - Phthalic Anhydride Reflux, recommended for polyethers and polyesters.

1.1.4Test Method D - Imidazole"“Catalyzed Phthalic Anhydride Pressure Bottle, recommended for polyethers, polyesters, polymer polyols, and amine-initiated polyols.

1.1.5Test Method E - Imidazole-Catalyzed Pyromellitic Dianhydride Esterification, recommended for polyols used for flexible and rigid polyurethane foams and urethane elastomers. It is recommended for polyester polyols, polyether polyols, amine-started polyols, and polymer polyols (polyacrylonitrile/copolystyrene-based).

1.2Another ASTM test method for measuring hydroxyl groups is Test Method E222.

1.3The values stated in SI units are to be regarded as the standard.

1.4This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

Note 1:This standard, ISO 14900 and ISO 6796 address the same subject matter, but differ in technical content.

1.5This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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