ASTM_D_7389_-_07_2019.pdf

Designation:D738907(Reapproved 2019)Standard Test Method forAcid Number(Empirical)of Maleic Anhydride(MAH)GraftedWaxes1This standard is issued under the fixed designation D7389;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 test method covers the determination of the acidnumber of maleic anhydride(MAH)grafted waxes.Thenumber is obtained by direct titration of the material andindicates the amount of free acid present.1.2 This test method is applicable to MAH-grafted waxesbecause it uses a special sample preparation step(7.1)that isnot required for other waxes.The special sample preparationreverses the hydrolysis of acid anhydride that can occur duringstorage of the wax.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 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:2D1386 Test Method for Acid Number(Empirical)of Syn-thetic and Natural WaxesE200 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 free acidcontent of MAH-grafted waxes.The potential hydrolysis of theanhydride functionality of this wax in storage makes themunsuitable for determining free acid content by Test MethodD1386.Free acid content is a significant quality control test,and is a determinant of the utility of the wax.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 Solution(0.1N)Dissolve 6.6 g of potassium hydroxide in 5.6 g of distilledwater.Dilute with USSD3Adenatured ethanol or 95%ethanolto 1000 mL.Standardize with 0.1 N hydrochloric acid.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.Sample Preparation7.1 Melt 20 g of the sample wax in a 250-mLflask or beakerand heat to 180190C.Apply a slight vacuum as the waxmelts and hold at temperature for 10 to 15 min,or as long asbubbles appear in the melt.If a vacuum is not available,holdthe sample at 180190C for 4 h.Determination of the acidnumber is made immediately after dehydration.Over heating1This 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 July 1,2019.Published July 2019.Originally approvedin 2007.Last previous edition approved in 2012 as D738907(2012).DOI:10.1520/D7389-07R19.2For 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 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 or holding the sample for more than 4 h will cause excessdarkening of the wax and making the end point difficult to see(8.2).8.Procedure8.1 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 the mixture on a hot plate or water bath to dissolve thesample.Occasional swirling may be necessary.8.2 Add 3 to 5 drops of phenolphthalein indicator solutionand titrate the hot solution to the first persistent pink color.Theend point it taken when the pink color remains for at least 10s.Swirl the flask vigorously during the titration.If precipitationof waxes occurs during titratio