ASTM_D_6188_-_97_2008.pdf

Designation:D618897(Reapproved 2008)Standard Test Method forViscosity of Cellulose by Cuprammonium Ball Fall1This standard is issued under the fixed designation D6188;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 describes the procedure for estimatingthe molecular weight of cellulose by determining the viscosityof cuprammonium(CuAm)solutions of cellulosic materials,such as wood pulp,cotton,and cotton linters.This test methodis suitable for rapid,routine testing of large numbers ofsamples with high accuracy and precision.This test methodupdates and extends the procedure reported by the AmericanChemical Society(ACS).21.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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:3D1193 Specification for Reagent WaterD1695 Terminology of Cellulose and Cellulose DerivativesE438 Specification for Glasses in Laboratory Apparatus3.Terminology3.1 This standard terminology of cellulose and cellulosederivatives,see Terminology D1695.4.Summary of Test Method4.1 An in-process or finished product sample is taken.Allcooking and bleaching chemicals must be washed out ofin-process samples.Dry samples are wetted with demineral-ized water.Samples are either squeezed or pressed to 20 to40%consistency as necessary,then passed through a picker.4.2 The wet pulp sample is dried with air whose maximumtemperature is 120C and weighed under conditions that causethe specified quantity of sample to be obtained.The weighedsample is placed in a glass 120-mL(4-oz)bottle,steel shot areadded,a vacuum is pulled on the bottle,and 97 mL ofcuprammonium solution are added to the bottle.The bottle isplaced on a shaker to mix and dissolve the pulp sample in theCuAm solution.4.3 The dissolved sample is transferred to a glass viscositytube.The tube is mounted vertically with a bright light behindthe tube.A special glass bead(see 7.13)is dropped into thecenter of the solution in the tube.The time is measured inseconds(s)for the glass bead to pass between two marks on thetube which are 20 cm apart.This time(s)is the uncorrected“asis”cuprammonium ball fall viscosity.The temperature of thesolution is determined,and the correction factor for thistemperature is multiplied by the uncorrected viscosity of thesample.This gives the“as is”cuprammonium ball fall viscos-ity value.4.4 The“as is”viscosity value for the sample size used isconverted to the 2.50-g ACS viscosity by the equationsprovided in 14.4.The viscosity is reported in“ACS seconds.”5.Significance and Use5.1 This test method is suitable for use as a rapid control testfor pulp manufacture or for careful determination of theviscometric molecular weight of purified cotton or woodderived pulps.5.2 This test method is applicable over a very large range ofcellulose molecular weights because seven sample sizes aredefined.(Sample weights are reduced as cellulose molecularweight increases.)5.3 Cotton and high molecular weight pulps may be difficultto dissolve.(WarningThis test method is only valid if thesample dissolves completely without gels.)6.Interferences6.1 High temperature drying of pulp causes a reduction inviscosity.Therefore,limit the maximum temperature of the air1This 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 1,2008.Published June 2008.Originallyapproved in 1997.Last previous edition approved in 2003 as D6188 97(2003).DOI:10.1520/D6188-97R08.2Carver et al.,“A Standard Method for Determining the Viscosity of Cellulosein Cuprammonium Hydroxide,”Industrial and Engineering Chemistry,AnalyticalEdition,Vol 1,No 1,1929,pp.49-51.3For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 used to dry the sample to 120C and the maximum drying timeto 20 min to keep viscosity loss to a minimum.All in-processsamples must be washed to remove cooking and bleachingchemicals,because the presence of chemicals while drying willincrease viscosity loss.6.2 The weight of sample used with this test