1、Designation: D7409 15Standard 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
2、 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 procedure is based significantly on the GRIGG7 test procedure, Carboxyl End Group Content of Polyeth-ylene
3、Terephthalate (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.NOTE 1This test is also applicable t
4、o high strength geotextile 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 an
5、y, 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:2D123 Terminology Relating to Textiles3. Terminolog
6、y3.1 Definitions:3.1.1 automatic 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
7、 acid located at either end of 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 variou
8、stypes of material that form the 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 electroc
9、hemical potential, expressed asmV, of 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
10、 an acid and a base.3.1.8 yarns, na generic 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
11、deter-mination of carboxyl end groups (CEG) of PET 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 hydroxidere
12、quired to complete the titration with the PET solution 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 u
13、sed in eithergeogrids or geotextiles.1This test method 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 previ
14、ous edition approved in 2007 as D7409 071. DOI:10.1520/D7409-15.2For 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 websi
15、te.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 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 resist
16、ance of the yarns.5.3 This test does not set the limiting (maximum) value 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 r
17、esults 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 with a buretassemb
18、ly, magnetic stir bar, magnetic stir plate, and glassbeaker.6.3 A temperature bath or hot plate that can maintain atemperature of 100C.7. Reagents7.1 In all cases, reagent grade chemicals must be used.7.2 Ortho-Cresol (99 %)The solvent should be dis-pensed with an automatic dispensing system to prev
19、ent air orwater from entering the bottle.Alternatively, the solvent can bedistilled prior to use. A different solvent may be used providedthe user first demonstrates equivalence to test results measuredusing Ortho-Cresol.7.3 Dichloro Methane (99.5 %)The solvent shall befrom 1L bottles, opened within
20、 one week. Alternatively, thesolvent can be distilled prior to use. A different solvent may beused provided the user first demonstrates equivalence to testresults measured using Ortho-Cresol.7.4 Potassium Hydroxide0.005M potassium hydroxide inmethanol.8. Safety8.1 O-CreosolIt is both toxic and combu
21、stible. It may beabsorbed through the skin. Avoid inhalation and skin contact.Wear the appropriate safety equipment required for handling atall times. If contact is made with the skin wash the affected areawith soap and water for at least 15 to 20 min. In case of eyecontact, flush the eyes with wate
22、r for 20 min and get medicalattention immediately.8.2 Potassium HydroxideIt is toxic and flammable. Avoidskin contact and breathing vapors. If ingested, could cause painin the nose, mouth and throat. Could induce vomiting, diarrhea,dizziness, hypotension, collapse, coma, or death. In case of eyeor s
23、kin contact, wash with water for 15 to 20 min and seekmedical attention immediately.8.3 MethanolIt is moderately toxic and flammable. Avoidinhalation and skin contact. Methanol may be absorbedthrough the skin. Wear the appropriate safety clothing that isrequired for the chemical laboratory when hand
24、ling. If contactis made, wash the affected area with water for at least 15 or 20min, get medical treatment immediately. Keep solvent awayfrom sparks and flames.8.4 Dichloro MethaneIt is toxic and flammable. Avoidbreathing vapors and skin contact. If contact is made, wash theaffected area with water
25、for 15 to 20 min. Get medical attentionimmediately.9. Sample Preparation9.1 Collect a representative sample of yarns (3 to 4 g) fromthe longitudinal direction of the geogrid (or geotextile) toperform three (3) replicate CEG determinations.NOTE 2The coating on geogrid yarns must be completely removed
26、.The recommended solvent for removal of PVC coatings is methyl ethylketone. Other coatings may require different solvents.NOTE 3If the test is being performed on high strength geotextiles,collect a representative sample from the warp direction fibers, filaments oryarns to perform three (3) replicate
27、 CEG determinations.9.2 The fibers, filaments or yarns are cut into small pieces,2 to 5 mm in length.9.3 The fibers, filaments or yarns should be washed in ethylether to remove sizing agents, and subsequently dried over-night at 50C.10. Preparation of KOH/Methanol Solution10.1 Dissolve approximately
28、 0.2 g KOH ( 3 pellets) in 1L ofmethanol. After dissolution is complete, titrate with PotassiumHydrogen Phthalate (KHP) to determine the molarity of theKOH solution.10.2 Measure 0.01 to 0.02 g of KHP crystals into a 150 mlbeaker. Record mass of KHP to 60.0001 g. Dissolve KHP inapproximately 50 ml of
29、 DI water.10.3 Titrate the KHP with the KOH/methanol solution untilan endpoint of pH 7 is reached. Record the volume required toreach the endpoint.10.4 Repeat steps 10.2 and 10.3 until three measurementshave been obtained.10.5 Calculate the molarity of the KOH/methanol solutionusing the following fo
30、rmula:OH# 5 w/204.23! x 1/v! (1)where:w = weight of KHP (g), andv = volume to titrate to pH7 (L).11. Procedure11.1 Approximately 0.25 g of PET yarn is weighed to anaccuracy of 60.0001 g and placed into a 125 ml erlenmeyerflask. Then, 15 ml 6 0.1 ml of orthocresol solvent and amagnetic stir bar are a
31、dded.11.2 The flask is covered with a watch glass and placed ina hot source. The temperature of the solvent should be 80C(65C). The mixture of solvent and yarn should be maintainedat this temperature and stirred until the yarn is completelydissolved.NOTE 4If the yarn is not completely dissolved in 3
32、0 min, continueD7409 152heating, but inspect every 5 min. The total heating time should not begreater 45 min.11.3 Remove the flask from the hot source as soon as thePET yarn is completely dissolved and quench by carefullyadding 60 ml of dichloromethane to the orthocreosol solution.Stir for an additi
33、onal 5 min.11.4 Titrate the PET solution with KOH/methanol solutionusing an autotitrator.11.4.1 If colorimetric titration is used, 2 drops of 1 %bromophenol blue indicator in methanol should be added to thePET solution and titrated to a violet endpoint.11.5 The test procedure is performed on three s
34、amples anda blank. The blank shall be treated identically to the samples.12. Calculation12.1 Calculation to Determinate the CEG Content.12.2 CEG content is expressed in the units of mmol/Kg.12.3 The calculation is as follows:CEG 5 Vs 2 Vb!*1000!*M!#/w (2)where:Vs (ml) = volume of KOH solution to tit
35、rate the sample,Vb (ml) = volume of KOH solution to titrate the blank,M (mol/l) = molarity of KOH/methanol solution, andw (g) = weight of PET sample.13. Report13.1 Report the following information:13.1.1 Identify the product and location from which the testsample was taken from the product.13.1.2 Re
36、port the individual CEG values, the average valueand the coefficient of variation.14. Keywords14.1 carboxyl end group content; CEG; geogrid yarns;geotextile yarns; PET; polyethylene terephthalateASTM International takes no position respecting the validity of any patent rights asserted in connection
37、with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible te
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39、ation at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr
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