ASTM_D_4817_-_88_2012.pdf

Designation:D481788(Reapproved 2012)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 and health practices and determine the applica-bility of regulatory limitations prior to use.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Test Method for Sampling Liquid Oils and FattyAcids Commonly Used in Paints,Varnishes,and RelatedMaterials(Withdrawn 2003)3D1951 Test Method for Ash in Drying Oils and Fatty Acids(Withdrawn 2003)3D1959 Test Method for Iodine Value of Drying Oils andFatty Acids(Withdrawn 2006)3D1962 Test Method for Saponification Value of Drying Oils,Fatty Acids,and Polymerized Fatty Acids(Withdrawn2004)3D1965 Test Method for Unsaponifiable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Polymerized Fatty Acids(With-drawn 2007)3D1980 Test Method for Acid Value of Fatty Acids andPolymerized Fatty Acids(Withdrawn 2007)3D1982 Test Method for Titer of Fatty AcidsD1983 Test Method for Fatty Acid Composition by Gas-Liquid Chromatography of Methyl Esters(Withdrawn2003)3D4075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 valuestearic acid is produced in several grades.Two grades arecommonly used in rubber compounding where a 1.0 maximumiodine value is needed.These two grades are distinguished bytheir ratios of palmitic to stearic acid content.The physical andchemical properties of the stearic acid will change as thepalmitic/stearic acid ratio changes.The palmitic/stearic ratiomay be checked by Test Method D1983.(See Table 2 for atypical analysis of the Class 2 stearic acid.)(2)Stearic acid can be made to customer specifications byemploying various processing steps such as hydrogenation tolower iodine value,bleaching with diatomaceous earth toimprove color and distillation,or crystallization to changechain length distribution or improve color,or both.A combi-nation of the processing steps may be used to produce the finalproduct.5.Sampling5.1 Sampling to conduct tests as outlined in Section 2 shallbe carried out in accordance with Test Method D1466.1This classification is under the jurisdiction of ASTM Committee D11 onRubber and is the direct responsibility of Subcommittee D11.20 on CompoundingMaterials and Procedures.Current edition approved May 1,2012.Published June 2012.Originallyapproved in 1988.Last previous edition approved in 2005 as D4817 88(2005).DOI:10.1520/D4817-88R12.2For 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 States1 ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard.Users of this standard are expressly advised that determination of the validity of any such patent rights,and the riskof infringement of such rights,are entirely their own respons