1、Designation:D803616Standard Test Method forPolyurethane Raw Materials:Determination of Dimer Ratioin Pure MDI1This standard is issued under the fixed designation D8036;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method determines the ratio of the infraredabsorbance of uretidinedione(dimer)in methylene-4,4-di-(phenylisocyanate)to
3、 an infrared absorbance at a referencewavelength within the same material.It is applicable tomonomeric methylene-di(phenylisocyanate),or“Pure MDI,”containing95%orgreatermethylene-4,4-di(phenylisocyanate).1.2 This standard does not purport to address all of thesafety concerns,if any,associated with i
4、ts 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology
5、Relating to PlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Terminology in this test method is in accordance withTerminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 dimer,nuretidinedione,with the structure
6、 in Fig.1,is an undesirable reaction product of two or more isocyanategroups.4.Summary of Test Method4.1 The infrared spectrum of a dichloromethane solution ofthe sample is recorded in the 1600 to 2000 cm1region.Theabsorbance ratio of the peak maximum at approximately 1778cm1,corresponding to the ca
7、rbonyls present in uretidinedione,to the para-substituted ring combination peak maximum atapproximately 1900 cm1is calculated.5.Significance and Use5.1 This test method can be used for research or for qualitycontrol to determine the dimer ratio of Pure MDI.5.2 Uretidinedione begins forming in Pure M
8、DI with therate of formation increasing with increasing temperature.Highlevels can affect the appearance of Pure MDI and the quality ofproducts made from it.6.Apparatus6.1 SpectrometerA Fourier-Transform infrared spectrom-eter accurate to 0.2%transmission and capable of resolvingthe dimer peak maxim
9、um at approximately 1778 cm1andreference peak maximum at approximately 1900 cm1.6.2 Cell,sealed sodium chloride(NaCl)liquid absorptioncell with 0.5-mm path length.6.3 Glassware,25-mL,glass-stoppered,volumetric flaskand an all-glass syringe.7.Reagents and Materials7.1 Purity of ReagentsUse reagent gr
10、ade chemicals in alltests.Unless otherwise noted,all reagents conform to thespecifications of the Committee on Analytical Reagents of theAmerican Chemical Society where such specifications areavailable.3It is acceptable to use other grades,provided it isascertained that the reagent is of sufficientl
11、y high purity topermit its use without lessening the accuracy of the determi-nation.7.2 Dichloromethane,reagent grade.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials-Plastics and Elastomers.Cur
12、rent edition approved May 1,2016.Published May 2016.DOI:10.1520/D8036-16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM w
13、ebsite.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaan
14、d National Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Sampling8.1 Since organic isocyanates react with atmosphericmoisture,take special precautions in sampling.Usual sa
15、mplingmethods,even when conducted rapidly,can cause contamina-tion of the sample with insoluble urea.Therefore,blanket thesample with dry air or nitrogen at all times.(WarningDiisocyanates are eye,skin and respiratory irritants at concen-trations above the occupational exposure limit(TLV or PEL).Dii
16、socyanates can cause skin and respiratory sensitization(asthma)in some people.Once sensitized,it is essential to limitfurther exposure to diisocyanates.Use a combination ofengineering controls and personal protective equipment,in-cluding respiratory,skin and eye protection,to prevent over-exposure to diisocyanates.Consult the product suppliersSafety Data Sheet(SDS)for more detailed information aboutpotential health effects and other specific safety and handlinginstructions for the product.)9.Tes
