1、Designation: D 7409 071Standard Test Method forCarboxyl End Group Content of Polyethylene Terephthalate(PET) Yarns1This standard is issued under the fixed designation D 7409; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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.1NOTEThe equation is Section 10.5 was added editorially in December 2008.1. Scope1.1 This test procedure is based significantl
3、y on the GRIGG7 test procedure, Carboxyl End Group Content of Polyeth-ylene 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 ge
4、ogrid yarns that are madefrom PET resin.NOTE 1This test is also applicable to high strength geotextile yarnsthat are made from PET and are used in reinforcement applications.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibil
5、ity 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:2D 123 Terminology Relating to Textiles3. Terminology3.1 Definitions:3.1.1 Carboxyl End Groups (CEG
6、), n non-reacted car-boxylic acid groups of terephthalic acid located at either end ofa polymer chain.3.1.2 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 neutra
7、lization reaction between an acid and a base.3.1.3 potentiometric titration, na titration method thatmonitors the change in electrochemical potential, expressed asmV, of the solution as the titration proceeds.3.1.4 colorimetric titration, na titration method thatmonitors the change in color of the s
8、olution as the titrationproceeds. A chemical indicator sensitive to pH is added tocreate the color change.3.1.5 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 solut
9、ion.3.1.6 fibers, na generic term for any one of the varioustypes of material that form the basic structure of a geogrid (orgeotextile), which are characterized by having a length at least100 times its diameter.3.1.7 filaments, na continuous fiber of extremely longlength.3.1.8 yarns, na generic term
10、 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 80 C. 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 s
12、olution 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
13、 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 Dec. 1, 2007. Published March 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cu
14、stomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 The CEG content of the PET ya
15、rns 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 forvarious engineering applications. Such a specification is adecision of th
16、e 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
17、required for apotentiometric titration. The assembly consists of an automatictitrator fitted with a three electrode system together with a buretassembly, magnetic stir bar, magnetic stir plate, and glassbeaker.6.3 A temperature bath or hot plate that can maintain atemperature of 100 C.7. Reagents7.1
18、 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 prevent air orwater from entering the bottle.Alternatively, the solvent can bedistilled prior to use.7.3 Dichloro Methane (99.5%) The solvent shall befro
19、m 1L bottles, opened within one week. Alternatively, thesolvent can be distilled prior to use.7.4 Potassium Hydroxide 0.005M potassium hydroxidein methanol.8. Safety8.1 O-Creosol It is both toxic and combustible. It may beabsorbed through the skin. Avoid inhalation and skin contact.Wear the appropri
20、ate 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 minutes. In case of eyecontact, flush the eyes with water for 20 min and get medicalattention immediately.8.2 Potassium Hydroxide It is toxic and f
21、lammable.Avoid skin contact and breathing vapors. If ingested, couldcause pain in the nose, mouth and throat. Could inducevomiting, diarrhea, dizziness, hypotension, collapse, coma, ordeath. In case of eye or skin contact, wash with water for 15-20min and seek medical attention immediately.8.3 Metha
22、nol It is moderately toxic and flammable.Avoid inhalation and skin contact. Methanol may be absorbedthrough the skin. Wear the appropriate safety clothing that isrequired for the chemical laboratory when handling. If contactis made, wash the affected area with water for at least 15 or 20min, get med
23、ical treatment immediately. Keep solvent awayfrom sparks and flames.8.4 Dichloro Methane It is toxic and flammable. Avoidbreathing vapors and skin contact. If contact is made, wash theaffected area with water for 15 to 20 min. Get medical attentionimmediately.9. Sample Preparation9.1 Collect a repre
24、sentative sample of yarns (3-4 g) from thelongitudinal direction of the geogrid (or geotextile) to performthree (3) replicate CEG determinations.NOTE 2The coating on geogrid yarns must be completely removed.The recommended solvent for removal of PVC coatings is methyl ethylketone. Other coatings may
25、 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 CEG determinations.9.2 The fibers, filaments or yarns are cut into small pieces,2-5mminlength
26、.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 0.2 g KOH ( 3 pellets) in 1L ofmethanol. After dissolution is complete, titrate with PotassiumHydro
27、gen 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 60.0001g. Dissolve KHP inapproximately 50 ml of DI water.10.3 Titrate the KHP with the KOH/methanol solution untilan endpoint of pH 7 is reached. Re
28、cord 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 formula:OH 5 w/204.23! x 1/v! (1)where:w = weight of KHP (g),v = volume to titrate to pH7 (L)11. Proced
29、ure11.1 Approximately 0.25 g of PET yarn is weighed to anaccuracy of 6 0.0001 g and placed into a 125 ml erlenmeyerflask. Then, 15 ml 6 0.1ml of orthocresol solvent and amagnetic stir bar are added.11.2 The flask is covered with a watch glass and placed ina hot source. The temperature of the solvent
30、 should be 80C (65C). The mixture of solvent and yarn should be maintained atthis temperature and stirred until the yarn is completelydissolved.NOTE 4If the yarn is not completely dissolved in 30 minutes, continueheating, but inspect every 5 min. The total heating time should not begreater 45 min.11
31、.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 additional 5 min.11.4 Titrate the PET solution with KOH/methanol solutionusing an autotitrator.D7409071211.4.1 If col
32、orimetric 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 samples anda blank. The blank shall be treated identically to the samples.12. Calculation12.1 Calculatio
33、n to Determinate the CEG Content12.2 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 titrate the sample,Vb (ml) = volume of KOH solution to titrate the blank,M (mol/l) = molarity of KOH / m
34、ethanol solution, andw (g) = weight of PET sample.13. Report13.1 Identify the product and location from which the testsample was taken from the product.13.2 Report the individual CEG values, the average valueand the coefficient of variation.ASTM International takes no position respecting the validit
35、y of any patent rights asserted in connection 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
36、 to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarter
37、s. Your comments will receive careful consideration 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 i
38、s copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D74090713
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