1、Designation:D738907(Reapproved 2012)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
2、 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
3、 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 t
4、hat 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
5、 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:2D1386 Test Method for Acid Number(Empirical)of Syn-thetic and Natural WaxesE200 Practice for Preparation,Standardi
6、zation,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 acidco
7、ntent 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 An
8、alytical 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
9、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.Sampl
10、e 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 acidnu
11、mber is made immediately after dehydration.Over heatingor 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 x
12、ylene.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.1,2012.Published October 2012.Originallyapproved in 2007 as D738907.DOI:10.1520/D7389-07R12.2For referenced ASTM sta
13、ndards,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-
14、2959.United States1 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
15、 at least 10s.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.Toavoid saponification,do not reheat the solutio
16、n during thisoperation.9.Calculation9.1 Calculate the acid number as follows:Acid number5AN356.1!/Bwhere:A=millilitres of alkali solution required for titration of thesample,N=normality of the alkali solution,andB=grams of sample used.10.Precision and Bias10.1 PrecisionDuplicate results by the same operator shallnot be considered suspect unless the results are greater than astandard deviation of 0.8.10.2 BiasThis test method has no bias because the valuesproduced are defined only in terms of thi
