ASTM_D_4817_-_88_2021.pdf

Designation:D481788(Reapproved 2021)Standard Classification forRubber Compounding MaterialsStearic Acid1This standard is issued under the fixed designation D4817;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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This classification covers the compounding materialscommercially known as stearic acid.1.2 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.3 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1466 Test Method for Sampling Liquid Oils and FattyAcids Commonly Used in Paints,Varnishes,and RelatedMaterials(Withdrawn 2003)3D1951 Test Method for Ash in Drying Oils and Fatty Acids(Withdrawn 2003)3D1959 Test Method for Iodine Value of Drying Oils andFatty Acids(Withdrawn 2006)3D1962 Test Method for Saponification Value of Drying Oils,Fatty Acids,and Polymerized Fatty Acids(Withdrawn2004)3D1965 Test Method for Unsaponifiable Matter in DryingOils,Fatty Acids,and Polymerized Fatty Acids(With-drawn 2007)3D1980 Test Method for Acid Value of Fatty Acids andPolymerized Fatty Acids(Withdrawn 2007)3D1982 Test Method for Titer of Fatty AcidsD1983 Test Method for Fatty Acid Composition by Gas-Liquid Chromatography of Methyl Esters(Withdrawn2003)3D4075 Test Methods for Rubber Compounding MaterialsFlame Atomic Absorption AnalysisDetermination ofMetals3.Significance and Use3.1 Stearic acid is important in the rubber vulcanizationprocess.It is believed that the stearic acid reacts with zinc-oxide or other metallic oxides,during vulcanization,to form arubber soluble salt or soap,that reacts with the acceleratorenabling it to exert its full effect.3.2 Stearic acid of commerce is generally a mixture ofpalmitic,stearic,and oleic acids usually derived from tallowbase stock but can be derived from other fats and oils of animalor vegetable origins.4.Basis of Classification4.1 Classification of Stearic Acid by Classes:4.1.1 There are several different classes of stearic acid,based on stearic acid content and iodine value.There are twoclasses predominantly used in rubber compounding.4.1.1.1 Class Number 1:Stearic Acid Containing Unsatu-rated Fatty AcidsStearic acid containing unsaturated acids iscommonly referred to as rubber grade stearic acid.Threegrades are commonly available with low,medium,and highunsaturation.These grades of stearic acid are used in rubbercompounding where unsaturated fatty acids can be tolerated.(See Table 1 for typical analysis of Class 1 stearic acid.)4.1.1.2 Class Number 2Stearic Acid with Low Levels ofUnsaturated Fatty AcidsLow IV:(1)Low iodine value stearic acid is produced in severalgrades.Two grades are commonly used in rubber compoundingwhere a 1.0 maximum iodine value is needed.These twogrades are distinguished by their ratios of palmitic to stearicacid content.The physical and chemical properties of thestearic acid will change as the palmitic/stearic acid ratiochanges.The palmitic/stearic ratio may be checked by TestMethod D1983.(See Table 2 for a typical analysis of the Class2 stearic acid.)(2)Stearic acid can be made to customer specifications byemploying various processing steps such as hydrogenation to1This classification is under the jurisdiction of ASTM Committee D11 onRubber and Rubber-like Materials and is the direct responsibility of SubcommitteeD11.20 on Compounding Materials and Procedures.Current edition approved Nov.1,2021.Published January 2022.Originallyapproved in 1988.Last previous edition approved in 2017 as D4817 88(2017).DOI:10.1520/D4817-88R21.2For 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 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 Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1?lower iodine