1、Designation:D740915Standard Test Method forCarboxyl End Group Content of Polyethylene Terephthalate(PET)Yarns1This standard is issued under the fixed designation D7409;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、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 procedure is based significantly on the GRIGG7 test procedure,Carboxyl End Group Content of Polyeth-ylene Terephthalat
3、e(PET)Yarns.1.2 This test method is used to determine the concentration,in mmol/Kg,of carboxyl end groups(CEG)found in poly(eth-ylene terephthalate)(PET)yarns by titration.1.3 This test is applicable to geogrid yarns that are madefrom PET resin.NOTE1This test is also applicable to high strength geot
4、extile yarnsthat are made from PET and are used in reinforcement applications.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its
5、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:2D123 Terminology Relating to Textiles3.Terminology3.1 Definitions:3.1.1 aut
6、omatic titration,na titration method in which amachine is used that automatically dispenses small volumes ofthe titrant and monitors the pH or the electrochemical potentialof the solution.3.1.2 Carboxyl End Groups(CEG),nnon-reacted carbox-ylic acid groups of terephthalic acid located at either end o
7、f apolymer chain.3.1.3 colorimetric titration,na titration method that moni-tors the change in color of the solution as the titration proceeds.A chemical indicator sensitive to pH is added to create thecolor change.3.1.4 fibers,na generic term for any one of the varioustypes of material that form th
8、e basic structure of a geogrid(orgeotextile),which are characterized by having a length at least100 times its diameter.3.1.5 filaments,na continuous fiber of extremely longlength.3.1.6 potentiometric titration,na titration method thatmonitors the change in electrochemical potential,expressed asmV,of
9、 the solution as the titration proceeds.3.1.7 titration,ntitration is a standard laboratory methodof quantitative chemical analysis which can be used to deter-mine the concentration of a known reactant.Typically,thereaction is a neutralization reaction between an acid and a base.3.1.8 yarns,na gener
10、ic term for a continuous strand offibers,filaments,or material in a form suitable for knitting,weaving,or otherwise intertwining to form a textile relatedgeogrid(or geotextile).4.Summary of Test Method4.1 This method defines a specific procedure for the deter-mination of carboxyl end groups(CEG)of P
11、ET by a titrimetricmethod.4.2 PET yarns are dissolved in o-cresol at 80C.Thesolution is diluted with dichloro methane,and titrated againstKOH dissolved in methanol,by either a potentiometric orcolorimetric method.The amount of potassium hydroxiderequired to complete the titration with the PET soluti
12、on ismeasured and used to calculate to the concentration of CEGs.5.Significance and Use5.1 This test method can be used for manufacturing qualitycontrol or manufacturing quality assurance purposes to deter-mine the CEG concentration of PET yarns used in eithergeogrids or geotextiles.1This test metho
13、d is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.02 on Endur-ance Properties.Current edition approved Feb.15,2015.Published April 2015.Originallyapproved in 2007.Last previous edition approved in 2007 as D7409 071.DOI:10.1520/D740
14、9-15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C70
15、0,West Conshohocken,PA 19428-2959.United States1 5.2 The CEG content of the PET yarns may have aninfluence on the properties of the geosynthetic,such as itshydrolysis resistance.The lower the value,the higher thehydrolysis resistance of the yarns.5.3 This test does not set the limiting(maximum)value
16、 forvarious engineering applications.Such a specification is adecision of the design engineer,owner,and/or regulator.6.Apparatus6.1 An automatic titrator is the preferred equipment for thistest method.However,acceptable results can be achievedmanually with the use of a micro burette,with 10 ml capacityand accurate to 0.02 ml.6.2 A potentiometric titration assembly is required for apotentiometric titration.The assembly consists of an automatictitrator fitted with a three electrode system together
