1、Designation:D576802(Reapproved 2014)Standard Test Method forDetermination of Iodine Value of Tall Oil Fatty Acids1This standard is issued under the fixed designation D5768;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of l
2、ast 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 covers the Wijs procedure for deter-mination of unsaturation(iodine value)of tall oil fatty acids.1.2 Iodin
3、e value is a measure of the unsaturation of oils andfatty acids and is expressed in terms of the number ofcentigrams of iodine per gram of sample(weight percent ofabsorbed iodine).1.3 When this test method is used to determine the iodinevalue of fatty acids having conjugated systems,the result is no
4、ta measure of total unsaturated,but rather is an empirical valuethat affords a comparison of unsaturation.Total unsaturation ofconjugated systems may be measured in accordance with TestMethod D1541.1.4 The test method described here is not reliable for tall oilfatty acids containing an appreciable q
5、uantity of rosin.1.5 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.6 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
6、establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1541 Test Method for Total Iodine Value of Drying Oilsand Their Derivatives(Withdrawn 2006)3D1959
7、 Test Method for Iodine Value of Drying Oils andFatty Acids(Withdrawn 2006)3E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Significance and Use3.1 The iodine value of a fatty a
8、cid product is a measure ofthe unsaturated fatty acid content of that product and conse-quently a measure of the ease of oxidation or drying capacityof that fatty acid product.3.2 This test method measures the unsaturation as iodinevalue by addition of an iodine/chlorine reagent.The amount ofreagent
9、 absorbed is determined by back titrating the excessreagent and comparing it to a blank determination.3.3 In samples containing conjugated double bonds,theiodine value obtained is empirical since the reagent does notreact stoichiometrically with conjugated unsaturation.Whereno conjugation is present
10、,the iodine value obtained is ameasure of the total unsaturation.By using proper specimenweights,the empirical values obtained are useful for compara-tive purposes.3.4 This test method was developed in order to replace thehazardous solvent,carbon tetrachloride,used in Test MethodD1959 with the less
11、hazardous and more available solvents,iso-octane and cyclohexane.As data on the satisfactory use ofother solvents becomes available,this test method will beamended to include those solvents.3.5 This test method should have applicability to fatty acidsand oils other than tall oil fatty acid but that
12、possibility has notbeen investigated.4.Apparatus4.1 BottlesGlass-stoppered bottles or Erlenmeyer flasks of250-mL capacity.4.2 Pipets20 and 25-mL capacity.4.3 Analytical balance5.Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests unless otherwise specified.Unless otherwis
13、eindicated,it is intended that all reagents shall conform to theSpecifications of the Committee on Analytical Reagents of the1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.3
14、4 on Pine Chemicals and Hydrocarbon Resins.Current edition approved Dec.1,2014.Published December 2014.Originallyapproved in 1995.Last previous edition approved in 2010 as D5768 02(2010).DOI:10.1520/D5768-02R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Custome
15、r Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Con
16、shohocken,PA 19428-2959.United States1 American Chemical Society,where such specifications areavailable.4Other grades may be used provided it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.5.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water conformingto Type I of Specification D1193.5.3 Acetic Acid(Glacial)17.4 MVerify the absence ofsubstances reducing
