ASTM_D_6942_-_03_2019.pdf

Designation:D694203(Reapproved 2019)Standard Test Method forStability of Cellulose Fibers in Alkaline Environments1This standard is issued under the fixed designation D6942;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 a procedure for determiningthe effect of exposure to alkaline environments on the strengthof cellulose fibers.An alkaline environment is defined to beany matrix in which the pH is greater than 8 for a period of 2or more hours.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 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:2D1348 Test Methods for Moisture in Cellulose(Withdrawn2017)3D1695 Terminology of Cellulose and Cellulose Derivatives2.2 TAPPI(Technical Association of the Pulp&PaperIndustry)Standards:T 205 Forming Handsheets for Physical Tests of Pulp4T 231 Zero-span Breaking Strength of Pulp(Dry Zero-spanTensile)43.Terminology3.1 DefinitionsFor standard terminology of cellulose andcellulose derivatives,see Terminology D1695.4.Summary of Test Method4.1 This test method can be used to compare differentcellulose pulp fiber types based on their response to a standardalkaline solution.The stability factor defined below can beused to measure the effect of exposure to alkaline conditions onfiber strength.4.2 Cellulose fibers are treated with a standard alkalinesolution for a specified interval,washed free of alkali,and thenformed into standard handsheets(see TAPPI T 205)forstrength testing.Zero-span tensile testing(see TAPPI T 231)isused to determine the effect on fiber strength.4.3 A stability ratio is defined based on the ratio of thezero-span tensile of alkali treated fibers divided by the zero-span tensile of untreated(control)fibers.5.Significance and Use5.1 This method is intended to provide a generalized pro-cedure for determining the stability of cellulosic pulp fibersexposed to alkaline environments.Specifically,this methodallows various pulp types to be compared with respect to theeffect of exposure to alkaline conditions on the strength ofindividual cellulosic fibers based on a zero-span tensile test.The time intervals listed in the procedure are not critical,andmore intervals of shorter or longer duration may be added.Inaddition,the procedure may be simplified by removing some ofthe intermediate intervals so long as a range of intervals isdetermined.An example of a simplified procedure would be todetermine 4 intervals(for example,1 day,1 week,2 weeks,4weeks;or 1 day,3 day,7 day,14 day).5.2 The specified solution(1N NaOH)is strongly alkaline.Although this alkali concentration is higher than some envi-ronments that would be simulated by this test,the stronger pHprovides better differentiation between different cellulose fibertypes.Although alkaline stability based on other alkalis(forexample,KOH,Ca(OH)2,etc.)at a different concentrationcould be determined by this method,1N NaOH is to beconsidered the standard solution.Alkaline stability results from1This 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 Dec.1,2019.Published December 2019.Originallyapproved in 2003.Last previous edition approved in 2012 as D6942 03(2012).DOI:10.1520/D6942-03R19.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Technical Association of the Pulp and Paper Industry(TAPPI),15 Technology Parkway South,Norcross,GA 30092,http:/www.tappi.org.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 Principle