1、Designation: D 2857 95 (Reapproved 2001)Standard Practice forDilute Solution Viscosity of Polymers1This standard is issued under the fixed designation D 2857; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、 D 789, D 1243, D 1601, and D 4603,and Practice D 3591) 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 sp
4、ecific procedure is not concerned, 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
5、. Results are usually expressed 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 Me
6、thodsD 789.1.4 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 and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE
7、 1This standard and ISO 1628, “PlasticsDetermination ofViscosity Number and Limiting Viscosity Number,” are technicallyequivalent.2. Referenced Documents2.1 ASTM Standards:2D 445 Test Method for Kinematic Viscosity of Transparentand Opaque LiquidsD 446 Specifications and Operating Instructions for G
8、lassCapillary Kinematic ViscometersD 789 Test Methods for Determination of Relative Viscos-ity, and Moisture Content of Polyamide (PA)D 883 Terminology Relating to PlasticsD 1243 Test Method for Dilute Solution Viscosity of VinylChloride PolymersD 1600 Terminology for Abbreviated Terms Relating toPl
9、asticsD 1601 Test Method for Dilute Solution Viscosity of Eth-ylene PolymersD 3591 Practice for Determining Logarithmic ViscosityNumber of Poly(Vinyl Chloride) (PVC) in FormulatedCompoundsD 4603 Test Method for Determining Inherent Viscosity ofPoly(Ethylene Terephthalate) (PET) by Glass CapillaryVis
10、cometerD 5226 Practice for Dissolving Polymer MaterialsE1 Specification for ASTM Thermometers2.2 ISO Standard:1628/1 Guidelines for the Standardization of Methods forthe Determination of Viscosity Number and LimitingViscosity Number of Polymers in Dilute Solution32.3 National Institute of Standards
11、and Technology Docu-ment:Circular No. C602 Testing of Glass Volumetric Apparatus43. Terminology3.1 DefinitionsTerms and definitions in TerminologyD 883 and abbreviations in Terminology D 1600 are applicableto this practice.The following definitions5are applicable to thispractice.3.1.1 inherent visco
12、sity, hinh, nthe ratio of the naturallogarithm of the relative viscosity to the mass concentration ofthe polymer, c: hinh= (ln hr)/c.3.1.1.1 DiscussionAlso known as the logarithmic viscos-ity number, hln. See also 3.1.3.3.1.2 intrinsic viscosity, h, nthe limiting value of thereduced viscosity or the
13、 inherent viscosity at infinite dilutionof the polymer: h 5c0limhi/c! 5c0limhinh.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved February 15, 1995. Published April 1995. Or
14、iginallypublished as D 2857 70. Last previous edition D 2857 93.2For 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.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.5International Union of Pure and Applied Chemistry, Compendium of
16、 Macro-molecular Nomenclature, Blackwell Scientific Publications, Oxford, England, 1991.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2.1 DiscussionAlso known as the limiting viscositynumber and in the literature as the Staudin
17、ger index. See also3.1.3.3.1.3 reduced viscosity, nthe ratio of the relative viscosityincrement to the mass concentration of the polymer, c, that is,hi/c.3.1.3.1 DiscussionAlso known as the viscosity number.The unit must be specified; cm3/g is recommended.3.1.3.2 DiscussionThis quantity and those de
18、fined in3.1.1 and 3.1.2 are neither viscosities nor pure numbers. Theterms are to be looked upon as traditional names. Anyreplacement by consistent terminology would produce unnec-essary confusion in the polymer literature.3.1.4 relative viscosity, hr, nthe ratio of the viscosity ofthe solution, h,
19、to the viscosity of the solvent, hs, that is, hr= h/hs.3.1.4.1 DiscussionAlso known as the viscosity ratio.3.1.5 relative viscosity increment, hi, nthe ratio of thedifference between the viscosities of solution and solvent to theviscosity of the solvent, that is, hi=(h hs)/hs.3.1.5.1 DiscussionThe u
20、se 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 procedures are given for the determination ofthe dilute solution viscosity of polymers, including descrip-tio
21、ns of apparatus, reagents and materials, and sample prepa-ration, as well as measurement procedures and calculations.4.2 If detailed test methods are available for the polymers ofinterest, such as those mentioned in 1.1, this practice providesinformation of a general nature to augment the detailedtr
22、eatments 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. When viscosity data are used in conjunction withother molecular parameters, the properties of polymers de
23、-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 dilute-solution viscosity and molecular pa-rameters such as molecular weight or chain length. The mostlimi
24、ting 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 branched species. Basically a measure ofmolecular size and not molecular weight, the dilute solutionviscos
25、ity 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 linear, but not for mostbranched, polymers.5.2.2 For reasons similar to those outlined in 5.2.1, it mus
26、tbe 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, empiricalrelationships can be developed between the dilute solutionviscosity of a polymer and its hy
27、drodynamic 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 mostimportant of these variables are solvent type and temperature.Thus, the solution viscosity of a give
28、n 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 highmolecular weight may depend on rate of shear in the viscom-eter, and the viscosity of a polyelectrol
29、yte (polymer containingionizable chemical groupings) will depend on the compositionand ionic strength of the solvent. Special precautions beyondthe scope of this practice are required when measuring suchpolymers.5.5 Finally, the viscosity of polymer solutions may beaffected drastically by the presen
30、ce 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 found conve-nient.6.2 Transfer Pipets,6sizes between 1 and 25 mL, as re-quired. Transfer pipets for use w
31、ith 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 the desired temperature (usually between 25 and150C). Less stringent temperature control (60.02C) is sat
32、is-factory upon demonstration that the precision of results is notaffected.6.4 Viscometer, glass capillary type, as described in Speci-fications D 446. Efflux time for the solvent and temperatureused shall be greater than 200 s (except that efflux time forsemimicro viscometers shall be greater than
33、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 be measured at asingle concentration, as for determination of the reducedviscosity (
34、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 different concentra-tions.6.4.2 The second type viscometer, commonly called adilution vi
35、scometer, 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 can be tested by adding aknown quantity of the solvent at the test temperature direct
36、ly tothe viscometer, mixing, measuring the viscosity, and then6Glassware should conform to the standards of accuracy in National Institute ofStandards and Technology Circular No. C602.D 2857 95 (2001)2making the next dilution. The viscosity of the pure solventmust be measured separately.6.4.3 An alt
37、ernative procedure is to start with the minimumvolume 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 ofvolum
38、es with which the viscometer will operate and the rangeof concentrations desired for test.6.5 Timer, graduated in divisions of 0.1 s or less, asdescribed in Test Method D 445.6.6 Thermometer, suitable for the specified test temperatureand conforming to the specifications of Specification E1,Kinemati
39、c Viscosity Thermometers ASTM 110C (for use at135C) and 118C (for use at 30C).6.7 Fritted Glass Filter Funnel,7coarse grade, or equiva-lent.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
40、materials have been used as heat-transferliquids: (1) silicone 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 m
41、ay be inhibited by the use of anantioxidant. The use of 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 s
42、ample dissolves only slowly inthe selected solvent, pretreating 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.9NOTE 4Caution: Take care to avoid overheatin
43、g the sample duringpulverization, which might lead to thermal degradation. 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-mLvolumetr
44、ic flask (or weigh and transfer quantitatively to theflask). If the sample is known to oxidize easily in thesubsequent dissolution step, the flask may be purged withnitrogen.NOTE 5Solution concentrations for some common polymers arerecommended inAppendix X1. Since other sizes of volumetric flasks ma
45、ybe used, depending on the viscometer size and the amount of sampleavailable, adjust sample weights and the solvent and solution volumesaccordingly.NOTE 6For greater reliability of results, select the sample size on thebasis of experiment to give a relative viscosity (viscosity ratio) near 1.5.If se
46、veral concentrations of a solution of a single sample are to be used(Note 8), select them so that the relative viscosity (viscosity ratio) falls inthe range from 1.2 to 2.0.NOTE 7Preparation of a single solution may often suffice, either fordetermining the relative viscosity (viscosity ratio) or inh
47、erent viscosity(logarithmic viscosity number), or 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 specime
48、n weights togive the desired solution concentration.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 inAppendix X1, Practice D 5226,orspecific test methods,
49、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.NOTE 8Caution: Complete solution of all of the specimen is essen-tial. When solution appears complete, examine the flask with care to besure that no undissolved material, gel particles, or foreign matter ispresent.9.3 Place the volumetric flasks containing the solution(s)and the pure solvent in the c
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