ASTM_D_1696_-_95_2011.pdf

Designation:D169695(Reapproved 2011)Standard Test Method forSolubility of Cellulose in Sodium Hydroxide1This standard is issued under the fixed designation D1696;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 method2is intended for application todissolving-type cellulose pulps prepared from cotton or wood.The procedure is not directly applicable to unrefined pulps foruse in chemical conversion processes because solubility equi-librium may not be attained within the specified extractiontime.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 consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterD1347 Test Methods for Methylcellulose(Withdrawn2003)4D1348 Test Methods for Moisture in Cellulose2.2 TAPPI Standard:T 429 Method for Alpha-Cellulose in Paper53.Summary of Test Method3.1 Pulp is steeped in a sodium hydroxide solution of aspecified concentration for 1 h at 20C.The soluble fraction isestimated by dichromate oxidation of the filtered steepingalkali.The concentration of sodium hydroxide used in the pulpextraction process must be reported as part of the analyticalresult.Sodium hydroxide concentrations of 10,18,and 21.5%are most frequently used.Data are reported as percent of drysample weight.3.2 The extraction procedure avoids dilution sequences,andtherefore,the results are not comparable to data obtained by thealpha,beta,gamma methods of pulp fractionation(see TAPPIMethod T 429).The terms“alpha-,”“beta-,”or“gamma-”cellulose must not be applied to any test values obtained by thisprocedure since they are defined only by the method of theirdetermination.3.3 The essential feature of the method is to prepare sodiumhydroxide extracts and oxidize the soluble material withdichromate as described.Alternative methods of estimatingdichromate by titration with ferrous ammonium sulfate andsodium thiosulfate are described.4.Significance and Use4.1 The measurement of soluble oxidizable components ofcellulose in sodium hydroxide is indicative of the purity of thecellulose sample,since pure cellulose is insoluble in sodiumhydroxide.Theextractedcomponentsaretypicallyhemicelluloses,which are naturally present in the wood.Differences in pulp purity can have a dramatic impact on theprocessing and properties of the cellulose derivatives producedfrom the pulp.5.Apparatus5.1 Constant-Temperature BathA water bath maintainedat 20 6 0.2C.5.2 StirrerMechanical stirrer as shown in Fig.1.All partsin contact with solutions must be of stainless steel.The stirrermotor shall be a variable speed laboratory motor with 1500rpm max speed.5.3 Fritted-Glass Filter CrucibleA fritted-glass filtercrucible,coarse porosity(pore size 40 to 60 m),of 30-mLcapacity.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1,2011.Published June 2011.Originallyapproved in 1959.Last previous edition approved in 2006 as D1696 95(2006).DOI:10.1520/D1696-95R11.2This test method is an adaptation of the method designated CCA 8:55 by theAnalysis Committee of the Central Committee of the Cellulose Industry of theSwedish Association of Pulp and Paper Engineers.This test method is alsocomparable with the TAPPI Tentative Standard T 235 m-58,Solubility of Pulp inCold Sodium Hydroxide.3For 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.4The last approved version of this historical standard is referenced onwww.astm.org.5Available from Technical Association of the Pulp and Paper Industry(TAPPI),P.O.Box 105113,Atlanta,GA30348;15 Technology Parkway South,Norcross,GA30092.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.4 Electrometric Titration ApparatusFor estimation ofdichromate by titration with ferrous ammonium sulfate.Anindicator may be used as described in 8.6,but for rapid,accurate analysis an electrometric apparatus is recommended.6.Purity of Reagents6.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated,it is intended that all reagents shallconform to the specifications