ASTM_D_3644_-_15.pdf

Designation:D364415Standard Test Method forAcid Number of Styrene-Maleic Anhydride Resins1This standard is issued under the fixed designation D3644;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 measurement of the freeacidity present in styrene-maleic anhydride resins.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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:2D329 Specification for AcetoneD1193 Specification for Reagent Water3.Terminology3.1 Definitions:3.1.1 acid numberthe number of milligrams of potassiumhydroxide(KOH)required to neutralize the alkali-reactivegroups in 1 g of material under the conditions of test.4.Significance and Use4.1 This test method is used to determine the property ofstyrene-maleic anhydride resins functionality.Acid functional-ity determines the utility of resin as well as being a significantquality control test.4.2 Because some of the anhydride functionality has beenhydrolyzed in the manufacturing process,direct titration withbase will produce erroneous data on the total acid content ofthe fully hydrolyzed resin in use.This test method chargesexcess alkali to hydrolize the anhydride functionality andneutralize the resulting acid.The remaining unreacted alkali isthen back titrated with a standardized acid solution and the acidcontent is determined by difference.5.Reagents and Materials5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water conformingto Specification D1193.5.3 Acetone,conforming to the requirements described inSpecification D329.5.4 Phenolphthalein Indicator Solution(20 g/L)Dissolve10 g of phenolphthalein in 100 mL of acetone.5.5 Sodium Hydroxide,Standard Solution(0.1 N)Dissolve 7 g of sodium hydroxide(NaOH)in 7 mL of water,and filter the resulting solution through a glass mat in a Goochcrucible with the aid of suction.Do not wash the residue.Dilute two thirds of the clear filtrate to 1 L with freshly boiledwater.Standardize against National Institute of Standards andTechnology standard sample of acid potassium phthalate No.84,using phenolphthalein as the indicator.Do not adjust theconcentration of the solution,but calculate the normality.5.6 Sulfuric Acid,Standard Solution(0.1 N)Measure out3 mLof concentrated sulfuric acid(H2SO4)(d=1.84)and pourit slowly,and with constant stirring,into about 100 mL ofwater.Cool to room temperature,mix thoroughly,and dilute to1 L.Standardize against 0.1 N NaOH solution,as prepared in4.5,using phenolphthalein as the indicator.Do not adjust theconcentration of the solution,but calculate the normality.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 1983.Last previous edition approved in 2012 as D3644 06(2012).DOI:10.1520/D3644-15.2For 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.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Procedure6.1 Weigh 0.1 g of the sample to the nearest 0.0001 g intoa 250-mL Erlenmeyer flask.6.2 Add 150 6 2 mL of acetone to the flask,stopper it,andswirl it until the sample is dissolved.All 0.2 mL of phenol-phthalein indicator solution and titrate with NaOH solution tothe end point,a faint pink color which