1、Designation: D2857 16Standard Practice forDilute Solution Viscosity of Polymers1This standard is issued under the fixed designation D2857; 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 paren
2、theses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the determination of the dilutesolution viscosity of polymers. There are several ASTMstandards (Test Methods D789, D1243, D1601,
3、and D4603,and Practice D3591) that describe dilute solution viscosityprocedures for specific polymers, such as nylon, poly(vinylchloride), polyethylene, and poly(ethylene terephthalate). Thispractice is written to augment these standards when problemsarise with which the specific procedure is not co
4、ncerned, orwhen no standard is available for the polymer under investi-gation.1.2 This practice is applicable to all polymers that dissolvecompletely without chemical reaction or degradation to formsolutions that are stable with time at a temperature betweenambient and 150C. Results are usually expr
5、essed as relativeviscosity (viscosity ratio), inherent viscosity (logarithmic vis-cosity number), or intrinsic viscosity (limiting viscosity num-ber) (see 3.1).1.3 For polyamides, relative viscosity values by this proce-dure are not equivalent to those determined by Test MethodsD789.1.4 The values s
6、tated 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 use. It is theresponsibility of the user of this standard to establish appro-priate safety
7、and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This standard and ISO 1628, “PlasticsDetermination ofViscosity Number and Limiting Viscosity Number,” are technicallyequivalent.2. Referenced Documents2.1 ASTM Standards:2D445 Test Method for Kinematic
8、 Viscosity of Transparentand Opaque Liquids (and Calculation of Dynamic Viscos-ity)D446 Specifications and Operating Instructions for GlassCapillary Kinematic ViscometersD789 Test Methods for Determination of Solution Viscosi-ties of Polyamide (PA)D883 Terminology Relating to PlasticsD1243 Test Meth
9、od for Dilute Solution Viscosity of VinylChloride PolymersD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD1601 Test Method for Dilute Solution Viscosity of Ethyl-ene PolymersD3591 Test Method for Determining Logarithmic ViscosityNumber of Poly(Vinyl Chloride) (PVC) in FormulatedCompound
10、sD4603 Test Method for Determining Inherent Viscosity ofPoly(Ethylene Terephthalate) (PET) by Glass CapillaryViscometerD5226 Practice for Dissolving Polymer MaterialsE1 Specification for ASTM Liquid-in-Glass Thermometers2.2 ISO Standard:1628/1 Guidelines for the Standardization of Methods forthe Det
11、ermination of Viscosity Number and LimitingViscosity Number of Polymers in Dilute Solution32.3 National Institute of Standards and Technology Docu-ment:Circular No. C602 Testing of Glass Volumetric Apparatus41This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct r
12、esponsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Sept. 1, 2016. Published September 2016. Originallyapproved in 1970. Last previous edition approved in 2007 as D2857 - 95(2007),which was withdrawn January 2016 and reinstated in September 2016. DOI:10.1520/D2857-16.
13、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.3Available from American National Standards Institute (ANSI),
14、 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
15、9428-2959. United States13. Terminology3.1 Definitions:3.1.1 Terms and definitions in Terminology D883 and ab-breviations in Terminology D1600 are applicable to thispractice. The following definitions5are applicable to thispractice.3.1.2 inherent viscosity, inh,nthe ratio of the naturallogarithm of
16、the relative viscosity to the mass concentration ofthe polymer, c: inh= (ln r)/c.3.1.2.1 DiscussionAlso known as the logarithmic viscos-ity number, ln. See also 3.1.4.3.1.3 intrinsic viscosity, , nthe limiting value of thereduced viscosity or the inherent viscosity at infinite dilution ofthe polymer
17、:# 5c0limi/c! 5c0liminh.3.1.3.1 DiscussionAlso known as the limiting viscositynumber and in the literature as the Staudinger index. See also3.1.4.3.1.4 reduced viscosity, nthe ratio of the relative viscosityincrement to the mass concentration of the polymer, c, that is,i/c.3.1.4.1 DiscussionAlso kno
18、wn as the viscosity number.The unit must be specified; cm3/g is recommended.3.1.4.2 DiscussionThis quantity and those defined in 3.1.2and 3.1.3 are neither viscosities nor pure numbers. The termsare to be looked upon as traditional names.Any replacement byconsistent terminology would produce unneces
19、sary confusionin the polymer literature.3.1.5 relative viscosity, r,nthe ratio of the viscosity ofthe solution, , to the viscosity of the solvent, s, that is, r= s.3.1.5.1 DiscussionAlso known as the viscosity ratio.3.1.6 relative viscosity increment, i,nthe ratio of thedifference between the viscos
20、ities of solution and solvent to theviscosity of the solvent, that is, i=( s)/s.3.1.6.1 DiscussionThe use of the term specific viscosityfor this quantity is discouraged, since the relative viscosityincrement does not have the attributes of a specific quantity.4. Summary of Practice4.1 General proced
21、ures are given for the determination ofthe dilute solution viscosity of polymers, including descrip-tions of apparatus, reagents and materials, and samplepreparation, as well as measurement procedures and calcula-tions.4.2 If detailed test methods are available for the polymers ofinterest, such as t
22、hose mentioned in 1.1, this practice providesinformation of a general nature to augment the detailedtreatments in the relevant test methods.5. Significance and Use5.1 The determination of dilute solution viscosity providesone item of information towards the molecular characterizationof polymers. Whe
23、n viscosity data are used in conjunction withother molecular parameters, the properties of polymers de-pending on their molecular structure may be predicted.5.2 Viscosity is dependent on molecular weight distribution,so with certain restrictions, satisfactory correlations can beobtained between dilu
24、te-solution viscosity and molecular pa-rameters such as molecular weight or chain length. The mostlimiting restrictions that must be observed are as follows:5.2.1 It must be known that the polymers used to establishthe correlations and those to which they are applied do notconsist of or contain bran
25、ched species. Basically a measure ofmolecular size and not molecular weight, the dilute solutionviscosity can be correlated appropriately with molecularweight or chain length only if there is a unique relationshipbetween the mass and the size of the dissolved polymermolecules. This is the case for l
26、inear, but not for mostbranched, polymers.5.2.2 For reasons similar to those outlined in 5.2.1, it mustbe required that the polymers to which the correlations areapplied have the same chemical composition as those used inestablishing the relationships.5.3 For polymers meeting the restrictions of 5.2
27、, empiricalrelationships can be developed between the dilute solutionviscosity of a polymer and its hydrodynamic volume oraverage chain dimension (radius of gyration or end-to-enddistance). Such relationships depend upon any variables influ-encing this molecular size of the dissolved polymer. The mo
28、stimportant of these variables are solvent type and temperature.Thus, the solution viscosity of a given polymer specimendepends on the choice of these variables, and they must alwaysbe specified with the viscosity for complete identification.5.4 The solution viscosity of a polymer of sufficiently hi
29、ghmolecular weight may depend on rate of shear in theviscometer, and the viscosity of a polyelectrolyte (polymercontaining ionizable chemical groupings) will depend on thecomposition and ionic strength of the solvent. Special precau-tions beyond the scope of this practice are required whenmeasuring
30、such polymers.5.5 Finally, the viscosity of polymer solutions may beaffected drastically by the presence of recognized or unrecog-nized additives in the sample, including but not limited tocolorants, fillers, or low-molecular-weight species.6. Apparatus6.1 Volumetric Flasks,6100-mL or other size fou
31、nd conve-nient.6.2 Transfer Pipets,6sizes between 1 and 25 mL, as re-quired. Transfer pipets for use with polymer solutions shouldhave about 2 mm cut from their lower tips to permit more rapidtransfer of the solution to the viscometer.6.3 Constant-Temperature Bath, capable of maintaining60.01C at th
32、e desired temperature (usually between 25 and5International Union of Pure and Applied Chemistry, Compendium of Macro-molecular Nomenclature, Blackwell Scientific Publications, Oxford, England, 1991.6Glassware should conform to the standards of accuracy in National Institute ofStandards and Technolog
33、y Circular No. C602.D2857 162150C). Less stringent temperature control (60.02C) is satis-factory upon demonstration that the precision of results is notaffected.6.4 Viscometer, glass capillary type, as described in Speci-fications D446. Efflux time for the solvent and temperatureused shall be greate
34、r than 200 s (except that efflux time forsemimicro viscometers shall be greater than 80 s), to eliminatethe need for kinetic energy corrections.6.4.1 Two types of viscometers are commonly used: One isa constant-volume device of simple construction, recom-mended for use where solution viscosity is to
35、 be measured at asingle concentration, as for determination of the reducedviscosity (viscosity number) or inherent viscosity (logarithmicviscosity number). It may also serve for the determination ofthe intrinsic viscosity (limiting viscosity number) throughmeasurement of several solutions having dif
36、ferent concentra-tions.6.4.2 The second type viscometer, commonly called adilution viscometer, is a time-saving device for the determina-tion of intrinsic viscosity (limiting viscosity number) since itdoes not require constant liquid volume for operation. Severalconcentrations of a polymer solution
37、can be tested by adding aknown quantity of the solvent at the test temperature directly tothe viscometer, mixing, measuring the viscosity, and thenmaking the next dilution. The viscosity of the pure solventmust be measured separately.6.4.3 An alternative procedure is to start with the minimumvolume
38、of the pure solvent, then add aliquots of a concentratedstock solution to the viscometer to obtain values of the relativeviscosity (viscosity ratio) at successively higher concentra-tions. The choice of procedures is dictated by the range ofvolumes with which the viscometer will operate and the rang
39、eof concentrations desired for test.6.5 Timer, graduated in divisions of 0.1 s or less, asdescribed in Test Method D445.6.6 Thermometer, suitable for the specified test temperatureand conforming to the specifications of Specification E1,Kinematic Viscosity Thermometers ASTM 110C (for use at135C) and
40、 118C (for use at 30C).6.7 Fritted Glass Filter Funnel,7coarse grade, or equivalent.7. Reagents and Materials7.1 Solvents, as required, or as recommended in AppendixX1.7.2 Heat Transfer Liquid, for constant temperature bath.NOTE 2The following materials have been used as heat-transferliquids: (1) si
41、licone oil,8(2) mineral oil, (3) peanut oil, (4) water, and (5)water-miscible liquid, such as glycerin or ethylene glycol. The materialselected must not discolor or smoke on prolonged exposure at the testtemperature; in some cases discoloring may be inhibited by the use of anantioxidant. The use of
42、water or a water-miscible liquid facilitatescleaning glassware used in the test.7.3 Nitrogen, for purging.8. Sample Preparation8.1 Do not predry or condition the sample unless thematerial is known to be hygroscopic.8.2 If it is known that the sample dissolves only slowly inthe selected solvent, pret
43、reating the sample to reduce itsparticle size may be advisable.NOTE 3Some samples can be pulverized conveniently in a rotarycutting mill with a 20-mesh screen at the outlet of its pulverizingchamber.9(WarningTake care to avoid overheating the sample duringpulverization, which might lead to thermal d
44、egradation. Low-meltingpolymers, or hard, tough samples, often can be satisfactorily pulverizedonly at very low temperature as provided by dry ice or liquid nitrogen.)9. Procedure9.1 Weigh an appropriate sample into a tared 100-mLvolumetric flask (or weigh and transfer quantitatively to theflask). I
45、f the sample is known to oxidize easily in thesubsequent dissolution step, the flask may be purged withnitrogen.NOTE 4Solution concentrations for some common polymers arerecommended in Appendix X1. Since other sizes of volumetric flasks maybe used, depending on the viscometer size and the amount of
46、sampleavailable, adjust sample weights and the solvent and solution volumesaccordingly.NOTE 5For greater reliability of results, select the sample size on thebasis of experiment to give a relative viscosity (viscosity ratio) near 1.5.If several concentrations of a solution of a single sample are to
47、be used(see Warning in 9.2), select them so that the relative viscosity (viscosityratio) falls in the range from 1.2 to 2.0.NOTE 6Preparation of a single solution may often suffice, either fordetermining the relative viscosity (viscosity ratio) or inherent viscosity(logarithmic viscosity number), or
48、 as a stock solution for use in a dilutionviscometer to determine the intrinsic viscosity (limiting viscosity num-ber). If more than one solution concentration is desired, weigh a series ofspecimens (often four) into separate flasks, selecting specimen weights togive the desired solution concentrati
49、on.9.2 Add approximately 50 cm3of solvent to each specimenflask, purge with nitrogen if necessary, and shake on alaboratory shaker. Elevated temperature may enhance thesolution rate as suggested in Appendix X1, Practice D5226,orspecific test methods, but this approach should be used withcaution. Some polymers and solvents have limited high-temperature stability. If solution preparation requires an el-evated temperature, subject a flask of pure solvent to the sameconditions as the polymer solution. (WarningCompletesolution of all
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