ASTM_D_3432_-_89_1996e1.pdf

Designation:D 3432 89(Reapproved 1996)e1Standard Test Method forUnreacted Toluene Diisocyanates in Urethane Prepolymersand Coating Solutions by Gas Chromatography1This standard is issued under the fixed designation D 3432;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTEEditorial changes were made throughout in November 1996.1.Scope1.1 This test method covers the determination of freetoluene diisocyanates in urethane prepolymers and unpig-mented coating solutions.NOTE1This test method may also be useful for the determination offree isocyanate monomers of other types upon taking precautions toconfirm suitability.1.2 There is no reason to believe this test method would notwork for pigmented coatings.1.3 The values stated in inch-pound units are to be regardedas the standard.The values given in parentheses are forinformation only.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For a specifichazard statement,see Section 8.2.Referenced Documents2.1 ASTM Standards:D 2372 Practice for Separation of Vehicle from Solvent-Reducible Paints2D 2698 Test Method for Determination of Pigment Contentof Solvent-Reducible Paints by High-Speed Centrifuging2E 260 Practice for Packed Column Gas Chromatography33.Summary of Test Method3.1 A standard solution of the diisocyanate is analyzed bygas chromatography using an internal standard technique.Theunknown specimen is then chromatographed,again using aninternal standard,and a response factor is calculated from thestandard solution.The unreacted diisocyanate content of theunknown is calculated from the chromatogram of the speci-men.4.Significance and Use4.1 This test method provides a measurement of the unre-acted diisocyanate content of urethane prepolymers and coat-ing solutions.This measurement is of basic importance to thehealth of the users.5.Interferences5.1 Under the test conditions described in this test method,other diisocyanates or impurities having identical or nearlyidentical elution times may interfere.It is generally necessaryto know the identity of the diisocyanate being used in thespecimen being tested,either by knowledge of the compositionor by a separate analysis.5.2 The temperature specifications for the injection port andcolumn oven must be strictly followed to prevent thermaldecomposition of the specimen.Decomposition can be de-tected by the failure of the recorder pen to return to the baselineafter elution of the diisocyanate monomer.5.3 Since resin solution specimens leave a nonvolatileresidue in the injection port,the use of glass injection portliners is recommended.The glass liner should be changed dailyor after each group of 10 specimens that are analyzed.5.4 Since diisocyanates are highly reactive with water,asuitable drying cartridge should be used in the carrier gas line.6.Apparatus6.1 Gas Chromatograph equipped with flame ionizationdetector(FID)and capable of linear temperature programmingto 300C.6.2 Chromatographic Column,6.6 ft(2 m)by 0.125-in.(3.2-mm)outside diameter,0.085-in.(2.1-mm)inside diameterstainless steel(or glass,2-mm inside diameter),packed with a10%methyl vinyl silicone on 80/100 mesh high performance,white,flux-calcined diatomaceous earth.The packing is pre-pared by dissolving 1.0 g of the methyl vinyl silicone in 50 mLof methylene chloride.This solution is placed in an evaporat-ing dish and 9 g of the diatomaceous earth is added with gentle1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.33 on Polymers and Resins.Current edition approved April 28,1989.Published July 1989.Originallypublished as D 3432 80.Last previous edition D 3432 80.2Annual Book of ASTM Standards,Vol 06.01.3Annual Book of ASTM Standards,Vol 14.02.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMstirring.The evaporating dish may be gently heated on a steambath or evaporated at room temperature.The packing should begently stirred,periodically,until dry and free-flowing.A newlypacked column should be conditioned overnight at 200C witha flow of dry carrier gas.NOTE2Any other column,either packed or capillary,may be substi-tuted if the required separation is obtained.NOTE3Other methods of packing preparation may be used,provideda free-flowing,uniformly coated packing results.6.3 Chromatograph