ASTM_D_1386_-_15.pdf

Designation:D138615Standard Test Method forAcid Number(Empirical)of Synthetic and Natural Waxes1This standard is issued under the fixed designation D1386;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of the acidnumber of synthetic waxes and natural waxes.The number isobtained by direct titration of the material and indicates theamount of free acid present.1.2 This test method,using an ethanol-xylene mixture,isapplicable to all natural waxes,including carnauba.The testmethod is also applicable to oxidized microcrystalline waxes,oxidized Fischer-Tropsch,oxidized polyethylene,and montanesters.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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.2.Referenced Document2.1 ASTM Standards:2E200 Practice for Preparation,Standardization,and Storageof Standard and Reagent Solutions for Chemical Analysis3.Terminology3.1 Definitions:3.1.1 acid number or acid valuethe number of milligramsof potassium hydroxide necessary to neutralize 1 g of thesample.4.Significance and Use4.1 This test method is used to determine the property ofacid functionality.Acid functionality determines the utility ofthe wax as well as being a significant Quality Control test.5.Apparatus5.1 Analytical Balance.5.2 Buret,50-mL,with 0.1-mL graduations.5.3 Flasks,acid value,250-mL.6.Reagents and Materials6.1 Purity of ReagentsReagent-grade chemicals orequivalent,as specified in Practice E200,shall be used in alltests.6.2 Ethanolic Potassium Hydroxide,Standard SolutionDissolve approximately 5.6 g of potassium hydroxide in 5.6 gof distilled water.Dilute with USSD3A denatured ethanol or95%ethanol to 1000 mL.Standardize with 0.1 N hydrochloricacid.6.3 Phenolphthalein Indicator Solution(10 g/litre)Dissolve 1 g of phenolphthalein in 100 mL of USSD3A,denatured ethanol or 95%ethanol.6.4 Xylene.7.Procedure7.1 Transfer 1 to 2 g of the sample,weighed to the nearest0.001 g,to a 250-mL acid-value flask.Add 40 mL of xylene.Heat on a hot plate or water bath to put the sample intosolution.Occasional swirling may be necessary.7.2 Add 3 to 5 drops of phenolphthalein indicator solutionand titrate the hot solution to the first persistent pink color.Theend point is taken when the pink color remains for at least 10 s.Swirl the flask vigorously during the titration.If precipitationof waxes occurs during titration,reheat the sample.Thetitration should be carried out as quickly as possible.Recordthe number of millilitres of standard alkali solution used.WarningTo avoid saponification,do not reheat the solutionduring this operation.7.3 Determine the blank titration value by repeating theprocedure of 7.1 and 7.2 without the addition of samplematerial.7.4 Run a total of three titrations of sample being tested andone blank.1This test method is under the jurisdiction ofASTM Committee D21 on Polishesand is the direct responsibility of Subcommittee D21.02 on Raw Materials.Current edition approved Oct.1,2015.Published October 2015.Originallyapproved in 1955 as D1386 55 T.Last previous edition approved in 2010 asD1386 10.DOI:10.1520/D1386-15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Calculation8.1 Calculate the acid number as follows:Acid number5A 2 B!3 N 356.1!/CA=millilitres of alkali solution required for titration of thesample,B=millilitres of alkali solution required for titration of theblank sample,N=normality of the alkali solution,andC=grams of sample used.9.Precision and Bias9.1 PrecisionDuplicate results by the same operator shallnot be considered suspect unless the results are greater than astandard deviation of 0.8.9.2 BiasThis test has no bias because the values producedare defined only in terms of this test method.10.Keywords10.1 acid number;free acid;natural waxes;polish;syntheticwaxes;titration;waxesASTM 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