ASTM D2857-22

Standard Practice for Dilute Solution Viscosity of Polymers

SIGNIFICANCE AND USE
5.1 The determination of dilute solution viscosity provides one item of information towards the molecular characterization of polymers. When viscosity data are used in conjunction with other molecular parameters, the properties of polymers depending on their molecular structure may be predicted.  
5.2 Viscosity is dependent on molecular weight distribution, so with certain restrictions, satisfactory correlations can be obtained between dilute-solution viscosity and molecular parameters such as molecular weight or chain length. The most limiting restrictions that must be observed are as follows:  
5.2.1 It must be known that the polymers used to establish the correlations and those to which they are applied do not consist of or contain branched species. Basically a measure of molecular size and not molecular weight, the dilute solution viscosity can be correlated appropriately with molecular weight or chain length only if there is a unique relationship between the mass and the size of the dissolved polymer molecules. This is the case for linear, but not for most branched, polymers.  
5.2.2 For reasons similar to those outlined in 5.2.1, it must be required that the polymers to which the correlations are applied have the same chemical composition as those used in establishing the relationships.  
5.3 For polymers meeting the restrictions of 5.2, empirical relationships can be developed between the dilute solution viscosity of a polymer and its hydrodynamic volume or average chain dimension (radius of gyration or end-to-end distance). Such relationships depend upon any variables influencing this molecular size of the dissolved polymer. The most important of these variables are solvent type and temperature. Thus, the solution viscosity of a given polymer specimen depends on the choice of these variables, and they must always be specified with the viscosity for complete identification.  
5.4 The solution viscosity of a polymer of sufficiently high molecular weight m...
SCOPE
1.1 This practice covers the determination of the dilute solution viscosity of polymers. There are several ASTM standards (Test Methods D789, D1243, D1601, and D4603, and Practice D3591) that describe dilute solution viscosity procedures for specific polymers, such as nylon, poly(vinyl chloride), polyethylene, and poly(ethylene terephthalate). This practice is written to augment these standards when problems arise with which the specific procedure is not concerned, or when no standard is available for the polymer under investigation.  
1.2 This practice is applicable to all polymers that dissolve completely without chemical reaction or degradation to form solutions that are stable with time at a temperature between ambient and 150°C. Results are usually expressed as relative viscosity (viscosity ratio), inherent viscosity (logarithmic viscosity number), or intrinsic viscosity (limiting viscosity number) (see 3.1).  
1.3 For polyamides, relative viscosity values by this procedure are not equivalent to those determined by Test Methods D789.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: This standard and ISO 1628, “Plastics—Determination of Viscosity Number and Limiting Viscosity Number,” are technically equivalent.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2022
• ICS: 83.080.01 - Plastics in general
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.70 - Analytical Methods

Relations

• Refers: ASTM D445-24 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Apr-2024
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D445-23 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D1243-22e1 - Standard Test Method for Dilute Solution Viscosity of Vinyl Chloride Polymers
• Effective Date: 01-May-2022
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D789-19 - Standard Test Method for Determination of Relative Viscosity of Concentrated Polyamide (PA) Solutions
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D789-18 - Standard Test Method for Determination of Relative Viscosity of Concentrated Polyamide (PA) Solutions
• Effective Date: 15-Jun-2018
• Refers: ASTM D4603-18 - Standard Test Method for Determining Inherent Viscosity of Poly(Ethylene Terephthalate) (PET) by Glass Capillary Viscometer
• Effective Date: 01-May-2018
• Refers: ASTM D1601-18 - Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers
• Effective Date: 01-May-2018

Overview

ASTM D2857-22: Standard Practice for Dilute Solution Viscosity of Polymers is a widely recognized ASTM standard that provides general guidelines for determining the dilute solution viscosity of polymers. This practice is especially valuable for polymers that dissolve fully without chemical reaction or degradation, forming stable solutions at temperatures from ambient up to 150°C. It is designed to supplement specific ASTM test methods for certain polymers and serves as a reference when a dedicated method does not exist for a particular polymer type.

Understanding dilute solution viscosity is essential for molecular characterization of polymers, providing insights into their size, structure, and molecular weight distribution. This information can then be correlated with important polymer properties, supporting quality control, research, and development in polymer industries.

Key Topics

• Purpose and Scope: ASTM D2857-22 covers general procedures for measuring the viscosity of dilute polymer solutions, using capillary viscometers and specific concentrations.
• Applicability: This method is suitable for polymers that are fully soluble and do not undergo chemical change or degradation during dissolution. The standard applies to a wide range of polymers, including those for which no other specific ASTM method is available.
• Viscosity Relationships: The methodology allows the determination of relative viscosity, inherent viscosity (logarithmic viscosity number), and intrinsic viscosity (limiting viscosity number). These parameters are key molecular indicators for polymers.
• Correlations and Limitations: Satisfactory correlations between viscosity and molecular parameters can be made primarily for linear polymers, not branched ones, and only when polymer chemical compositions match those used to establish the correlation.
• Test Conditions: Variables such as solvent type and temperature significantly impact solution viscosity and must be documented alongside test results.
• Reporting: Results must specify the viscosity value, solvent, concentration, and test temperature for reliable data comparison.

Applications

The ASTM D2857-22 standard is frequently used in:

• Polymer Research and Development: Assists in the molecular characterization of new polymer materials by providing viscosity data related to molecular weight and structure.
• Quality Control in Manufacturing: Ensures batch-to-batch consistency of polymer products by tracking molecular size and distribution through viscosity measurements.
• Material Selection and Specification: Facilitates the comparison of polymers in terms of solution behavior, supporting informed selection for specific applications.
• Supporting Other ASTM Methods: Can be applied to a variety of polymers, including nylon, poly(vinyl chloride), polyethylene, and poly(ethylene terephthalate), especially when standard test methods do not address unique scenarios or polymer types.

Note: For polyamides, relative viscosity values determined by this standard are not equivalent to those from ASTM D789.

Related Standards

• ASTM D789: Test Method for Relative Viscosity of Concentrated Polyamide (PA) Solutions
• ASTM D1243: Test Method for Dilute Solution Viscosity of Vinyl Chloride Polymers
• ASTM D1601: Test Method for Dilute Solution Viscosity of Ethylene Polymers
• ASTM D4603: Test Method for Inherent Viscosity of Poly(Ethylene Terephthalate)
• ASTM D3591: Test Method for Logarithmic Viscosity Number of PVC in Compounds
• ISO 1628: Plastics-Determination of Viscosity Number and Limiting Viscosity Number

Practical Value

Adopting ASTM D2857-22 supports standardized, reliable measurement of dilute solution viscosity, facilitating global consistency across polymer research, processing, and trade. By offering flexible, general guidance, this standard expands testing capabilities beyond polymer-specific methods and helps ensure robust data for critical product and process decisions.

Keywords: dilute solution viscosity, polymer viscosity measurement, ASTM D2857-22, molecular weight polymers, intrinsic viscosity, inherent viscosity, polymer solution testing, plastic quality control, polymer research standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D2857 − 22
Standard Practice for
Dilute Solution Viscosity of Polymers
This standard is issued under the fixed designation D2857; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This practice covers the determination of the dilute
solution viscosity of polymers. There are several ASTM
2. Referenced Documents
standards (Test Methods D789, D1243, D1601, and D4603,
2.1 ASTM Standards:
and Practice D3591) that describe dilute solution viscosity
procedures for specific polymers, such as nylon, poly(vinyl D445Test Method for Kinematic Viscosity of Transparent
and Opaque Liquids (and Calculation of DynamicViscos-
chloride), polyethylene, and poly(ethylene terephthalate). This
practice is written to augment these standards when problems ity)
D446Specifications and Operating Instructions for Glass
arise with which the specific procedure is not concerned, or
when no standard is available for the polymer under investi- Capillary Kinematic Viscometers
D789Test Method for Determination of Relative Viscosity
gation.
of Concentrated Polyamide (PA) Solutions
1.2 This practice is applicable to all polymers that dissolve
D883Terminology Relating to Plastics
completely without chemical reaction or degradation to form
D1243Test Method for Dilute Solution Viscosity of Vinyl
solutions that are stable with time at a temperature between
Chloride Polymers
ambient and 150°C. Results are usually expressed as relative
D1600TerminologyforAbbreviatedTermsRelatingtoPlas-
viscosity (viscosity ratio), inherent viscosity (logarithmic vis-
tics
cosity number), or intrinsic viscosity (limiting viscosity num-
D1601Test Method for Dilute Solution Viscosity of Ethyl-
ber) (see 3.1).
ene Polymers
1.3 For polyamides, relative viscosity values by this proce-
D3591Test Method for Determining Logarithmic Viscosity
dure are not equivalent to those determined by Test Methods
Number of Poly(Vinyl Chloride) (PVC) in Formulated
D789.
Compounds
D4603Test Method for Determining Inherent Viscosity of
1.4 The values stated in SI units are to be regarded as
Poly(Ethylene Terephthalate) (PET) by Glass Capillary
standard. No other units of measurement are included in this
Viscometer
standard.
D5226Practice for Dissolving Polymer Materials
1.5 This standard does not purport to address all of the
E2251Specification for Liquid-in-Glass ASTM Thermom-
safety concerns, if any, associated with its use. It is the
eters with Low-Hazard Precision Liquids
responsibility of the user of this standard to establish appro-
2.2 ISO Standard:
priate safety, health, and environmental practices and deter-
1628/1Guidelines for the Standardization of Methods for
mine the applicability of regulatory limitations prior to use.
the Determination of Viscosity Number and Limiting
NOTE 1—This standard and ISO 1628, “Plastics—Determination of
Viscosity Number of Polymers in Dilute Solution
Viscosity Number and Limiting Viscosity Number,” are technically
equivalent. 2.3 National Institute of Standards and Technology Docu-
ment:
1.6 This international standard was developed in accor-
Circular No. C602Testing of Glass Volumetric Apparatus
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsand the ASTM website.
is the direct responsibility of Subcommittee D20.70 on Analytical Methods. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
Current edition approved May 1, 2022. Published May 2022. Originally 4th Floor, New York, NY 10036, http://www.ansi.org.
approved in 1970. Last previous edition approved in 2016 as D2857-16. DOI: Available from National Institute of Standards and Technology (NIST), 100
10.1520/D2857-22. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2857 − 22
3. Terminology 5.2 Viscosityisdependentonmolecularweightdistribution,
so with certain restrictions, satisfactory correlations can be
3.1 Definitions:
obtained between dilute-solution viscosity and molecular pa-
3.1.1 For definitions of terms pertaining to plastics used in
rameters such as molecular weight or chain length. The most
thistestmethod,refertoTerminologyD883.Forabbreviations
limiting restrictions that must be observed are as follows:
used in this test method, refer to Terminology D1600, unless
5.2.1 It must be known that the polymers used to establish
otherwise indicated.
the correlations and those to which they are applied do not
3.1.2 inherent viscosity, η ,n—the ratio of the natural
inh
consist of or contain branched species. Basically a measure of
logarithm of the relative viscosity to the mass concentration of
molecular size and not molecular weight, the dilute solution
the polymer, c: η =(lnη )/c.
inh r
viscosity can be correlated appropriately with molecular
3.1.2.1 Discussion—Also known as the logarithmic viscos-
weight or chain length only if there is a unique relationship
ity number,η . See also 3.1.4.
ln
between the mass and the size of the dissolved polymer
3.1.3 intrinsic viscosity, [η], n—the limiting value of the
molecules. This is the case for linear, but not for most
reducedviscosityortheinherentviscosityatinfinitedilutionof
branched, polymers.
the polymer:
5.2.2 For reasons similar to those outlined in 5.2.1, it must
lim lim
@η# 5 ~η /c! 5 η . be required that the polymers to which the correlations are
c→0 i c→0 inh
3.1.3.1 Discussion—Also known as the limiting viscosity
applied have the same chemical composition as those used in
number and in the literature as the Staudinger index. See also
establishing the relationships.
3.1.4.
5.3 For polymers meeting the restrictions of 5.2, empirical
3.1.4 reduced viscosity, n—the ratio of the relative viscosity
relationships can be developed between the dilute solution
increment to the mass concentration of the polymer, c, that is,
viscosity of a polymer and its hydrodynamic volume or
η /c.
i average chain dimension (radius of gyration or end-to-end
3.1.4.1 Discussion—Also known as the viscosity number.
distance). Such relationships depend upon any variables influ-
The unit must be specified; cm /g is recommended.
encing this molecular size of the dissolved polymer. The most
3.1.4.2 Discussion—Thisquantityandthosedefinedin3.1.2
important of these variables are solvent type and temperature.
and 3.1.3 are neither viscosities nor pure numbers. The terms
Thus, the solution viscosity of a given polymer specimen
aretobelookeduponastraditionalnames.Anyreplacementby
dependsonthechoiceofthesevariables,andtheymustalways
consistent terminology would produce unnecessary confusion
be specified with the viscosity for complete identification.
in the polymer literature.
5.4 The solution viscosity of a polymer of sufficiently high
3.1.5 relative viscosity, η ,n—the ratio of the viscosity of
r
molecular weight may depend on rate of shear in the
the solution, η, to the viscosity of the solvent, η , that is, η
s r
viscometer, and the viscosity of a polyelectrolyte (polymer
=η⁄η .
s
containing ionizable chemical groupings) will depend on the
3.1.5.1 Discussion—Also known as the viscosity ratio.
composition and ionic strength of the solvent. Special precau-
3.1.6 relative viscosity increment, η ,n—the ratio of the tions beyond the scope of this practice are required when
i
differencebetweentheviscositiesofsolutionandsolventtothe measuring such polymers.
viscosity of the solvent, that is,η =(η−η )/η .
i s s
5.5 Finally, the viscosity of polymer solutions may be
3.1.6.1 Discussion—The use of the term specific viscosity
affected drastically by the presence of recognized or unrecog-
for this quantity is discouraged, since the relative viscosity
nized additives in the sample, including but not limited to
increment does not have the attributes of a specific quantity.
colorants, fillers, or low-molecular-weight species.
6. Apparatus
4. Summary of Practice
6.1 Volumetric Flasks, 100-mL or other size found conve-
4.1 General procedures are given for the determination of
nient.
the dilute solution viscosity of polymers, including descrip-
tions of apparatus, reagents and materials, and sample
6.2 Transfer Pipets, sizes between 1 and 25 mL, as re-
preparation, as well as measurement procedures and calcula-
quired. Transfer pipets for use with polymer solutions should
tions.
haveabout2mmcutfromtheirlowertipstopermitmorerapid
transfer of the solution to the viscometer.
4.2 Ifdetailedtestmethodsareavailableforthepolymersof
interest, such as those mentioned in 1.1, this practice provides
6.3 Constant-Temperature Bath, capable of maintaining
information of a general nature to augment the detailed
60.01°C at the desired temperature (usually between 25 and
treatments in the relevant test methods.
150°C). Less stringent temperature control (60.02°C) is satis-
factory upon demonstration that the precision of results is not
5. Significance and Use
affected.
5.1 The determination of dilute solution viscosity provides
6.4 Viscometer, glass capillary type, as described in Speci-
oneitemofinformationtowardsthemolecularcharacterization
fications D446. Efflux time for the solvent and temperature
of polymers.When viscosity data are used in conjunction with
other molecular parameters, the properties of polymers de-
Glassware should conform to the standards of accuracy in National Institute of
pending on their molecular structure may be predicted. Standards and Technology Circular No. C602.
D2857 − 22
polymers, or hard, tough samples, often can be satisfactorily pulverized
used shall be greater than 200 s (except that efflux time for
only at very low temperature as provided by dry ice or liquid nitrogen.)
semimicro viscometers shall be greater than 80 s), to eliminate
the need for kinetic energy corrections.
9. Procedure
6.4.1 Two types of viscometers are commonly used: One is
a constant-volume device of simple construction, recom-
9.1 Weigh an appropriate sample into a tared 100-mL
mended for use where solution viscosity is to be measured at a
volumetric flask (or weigh and transfer quantitatively to the
single concentration, as for determination of the reduced
flask). If the sample is known to oxidize easily in the
viscosity (viscosity number) or inherent viscosity (logarithmic
subsequent dissolution step, the flask may be purged with
viscosity number). It may also serve for the determination of
nitrogen.
the intrinsic viscosity (limiting viscosity number) through
NOTE 4—Solution concentrations for some common polymers are
measurement of several solutions having different concentra-
recommendedinAppendixX1.Sinceothersizesofvolumetricflasksmay
tions.
be used, depending on the viscometer size and the amount of sample
6.4.2 The second type viscometer, commonly called a
available, adjust sample weights and the solvent and solution volumes
dilution viscometer, is a time-saving device for the determina- accordingly.
tion of intrinsic viscosity (limiting viscosity number) since it NOTE 5—For greater reliability of results, select the sample size on the
basis of experiment to give a relative viscosity (viscosity ratio) near 1.5.
does not require constant liquid volume for operation. Several
If several concentrations of a solution of a single sample are to be used
concentrations of a polymer solution can be tested by adding a
(see Warning in 9.2), select them so that the relative viscosity (viscosity
knownquantityofthesolventatthetesttemperaturedirectlyto
ratio) falls in the range from 1.2 to 2.0.
the viscometer, mixing, measuring the viscosity, and then
NOTE 6—Preparation of a single solution may often suffice, either for
making the next dilution. The viscosity of the pure solvent
determining the relative viscosity (viscosity ratio) or inherent viscosity
(logarithmic viscosity number), or as a stock solution for use in a dilution
must be measured separately.
viscometer to determine the intrinsic viscosity (limiting viscosity num-
6.4.3 An alternative procedure is to start with the minimum
ber). If more than one solution concentration is desired, weigh a series of
volumeofthepuresolvent,thenaddaliquotsofaconcentrated
specimens (often four) into separate flasks, selecting specimen weights to
stock solution to the viscometer to obtain values of the relative
give the desired solution concentration.
viscosity (viscosity ratio) at successively higher concentra-
9.2 Add approximately 50 cm of solvent to each specimen
tions. The choice of procedures is dictated by the range of
flask, purge with nitrogen if necessary, and shake on a
volumes with which the viscometer will operate and the range
laboratory shaker. Elevated temperature enhances the solution
of concentrations desired for test.
rate as suggested in Appendix X1, Practice D5226, or specific
6.5 Timer, graduated in divisions of 0.1 s or less, as
test methods, but this approach should be used with caution.
described in Test Method D
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D2857 − 16 D2857 − 22
Standard Practice for
Dilute Solution Viscosity of Polymers
This standard is issued under the fixed designation D2857; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This practice covers the determination of the dilute solution viscosity of polymers. There are several ASTM standards (Test
Methods D789, D1243, D1601, and D4603, and Practice D3591) that describe dilute solution viscosity procedures for specific
polymers, such as nylon, poly(vinyl chloride), polyethylene, and poly(ethylene terephthalate). This practice is written to augment
these standards when problems arise with which the specific procedure is not concerned, or when no standard is available for the
polymer under investigation.
1.2 This practice is applicable to all polymers that dissolve completely without chemical reaction or degradation to form solutions
that are stable with time at a temperature between ambient and 150°C. Results are usually expressed as relative viscosity (viscosity
ratio), inherent viscosity (logarithmic viscosity number), or intrinsic viscosity (limiting viscosity number) (see 3.1).
1.3 For polyamides, relative viscosity values by this procedure are not equivalent to those determined by Test Methods D789.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—This standard and ISO 1628, “Plastics—Determination of Viscosity Number and Limiting Viscosity Number,” are technically equivalent.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D446 Specifications and Operating Instructions for Glass Capillary Kinematic Viscometers
D789 Test Method for Determination of Relative Viscosity of Concentrated Polyamide (PA) Solutions
D883 Terminology Relating to Plastics
D1243 Test Method for Dilute Solution Viscosity of Vinyl Chloride Polymers
D1600 Terminology for Abbreviated Terms Relating to Plastics
This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
Current edition approved Sept. 1, 2016May 1, 2022. Published September 2016May 2022. Originally approved in 1970. Last previous edition approved in 20072016 as
D2857 - 95D2857 - 16.(2007), which was withdrawn January 2016 and reinstated in September 2016. DOI: 10.1520/D2857-16. DOI: 10.1520/D2857-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2857 − 22
D1601 Test Method for Dilute Solution Viscosity of Ethylene Polymers
D3591 Test Method for Determining Logarithmic Viscosity Number of Poly(Vinyl Chloride) (PVC) in Formulated Compounds
D4603 Test Method for Determining Inherent Viscosity of Poly(Ethylene Terephthalate) (PET) by Glass Capillary Viscometer
D5226 Practice for Dissolving Polymer Materials
E1E2251 Specification for ASTM Liquid-in-Glass ThermometersLiquid-in-Glass ASTM Thermometers with Low-Hazard
Precision Liquids
2.2 ISO Standard:
1628/1 Guidelines for the Standardization of Methods for the Determination of Viscosity Number and Limiting Viscosity
Number of Polymers in Dilute Solution
2.3 National Institute of Standards and Technology Document:
Circular No. C602 Testing of Glass Volumetric Apparatus
3. Terminology
3.1 Definitions:
3.1.1 Terms and definitions in For definitions of terms pertaining to plastics used in this test method, refer to Terminology D883
and. For abbreviations in used in this test method, refer to Terminology D1600 are applicable to this practice. The following
definitions, unless otherwise indicated. are applicable to this practice.
3.1.2 inherent viscosity, η , n—the ratio of the natural logarithm of the relative viscosity to the mass concentration of the
inh
polymer, c: η = (ln η )/c.
inh r
3.1.2.1 Discussion—
Also known as the logarithmic viscosity number, η . See also 3.1.4.
ln
3.1.3 intrinsic viscosity, [η], n—the limiting value of the reduced viscosity or the inherent viscosity at infinite dilution of the
polymer:
lim lim
@η#5 ~η /c! 5 η .
c→0 i c→0 inh
3.1.3.1 Discussion—
Also known as the limiting viscosity number and in the literature as the Staudinger index. See also 3.1.4.
3.1.4 reduced viscosity, n—the ratio of the relative viscosity increment to the mass concentration of the polymer, c, that is, η /c.
i
3.1.4.1 Discussion—
Also known as the viscosity number. The unit must be specified; cm /g is recommended.
3.1.4.2 Discussion—
This quantity and those defined in 3.1.2 and 3.1.3 are neither viscosities nor pure numbers. The terms are to be looked upon as
traditional names. Any replacement by consistent terminology would produce unnecessary confusion in the polymer literature.
3.1.5 relative viscosity, η , n—the ratio of the viscosity of the solution, η, to the viscosity of the solvent, η , that is, η = η ⁄η .
r s r s
3.1.5.1 Discussion—
Also known as the viscosity ratio.
3.1.6 relative viscosity increment, η , n—the ratio of the difference between the viscosities of solution and solvent to the viscosity
i
of the solvent, that is, η = (η − η )/η .
i s s
3.1.6.1 Discussion—
The use of the term specific viscosity for this quantity is discouraged, since the relative viscosity increment does not have the
attributes of a specific quantity.
4. Summary of Practice
4.1 General procedures are given for the determination of the dilute solution viscosity of polymers, including descriptions of
apparatus, reagents and materials, and sample preparation, as well as measurement procedures and calculations.
4.2 If detailed test methods are available for the polymers of interest, such as those mentioned in 1.1, this practice provides
information of a general nature to augment the detailed treatments in the relevant test methods.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
D2857 − 22
5. Significance and Use
5.1 The determination of dilute solution viscosity provides one item of information towards the molecular characterization of
polymers. When viscosity data are used in conjunction with other molecular parameters, the properties of polymers depending on
their molecular structure may be predicted.
5.2 Viscosity is dependent on molecular weight distribution, so with certain restrictions, satisfactory correlations can be obtained
between dilute-solution viscosity and molecular parameters such as molecular weight or chain length. The most limiting
restrictions that must be observed are as follows:
5.2.1 It must be known that the polymers used to establish the correlations and those to which they are applied do not consist of
or contain branched species. Basically a measure of molecular size and not molecular weight, the dilute solution viscosity can be
correlated appropriately with molecular weight or chain length only if there is a unique relationship between the mass and the size
of the dissolved polymer molecules. This is the case for linear, but not for most branched, polymers.
5.2.2 For reasons similar to those outlined in 5.2.1, it must be required that the polymers to which the correlations are applied have
the same chemical composition as those used in establishing the relationships.
5.3 For polymers meeting the restrictions of 5.2, empirical relationships can be developed between the dilute solution viscosity
of a polymer and its hydrodynamic volume or average chain dimension (radius of gyration or end-to-end distance). Such
relationships depend upon any variables influencing this molecular size of the dissolved polymer. The most important of these
variables are solvent type and temperature. Thus, the solution viscosity of a given polymer specimen depends on the choice of these
variables, and they must always be specified with the viscosity for complete identification.
5.4 The solution viscosity of a polymer of sufficiently high molecular weight may depend on rate of shear in the viscometer, and
the viscosity of a polyelectrolyte (polymer containing ionizable chemical groupings) will depend on the composition and ionic
strength of the solvent. Special precautions beyond the scope of this practice are required when measuring such polymers.
5.5 Finally, the viscosity of polymer solutions may be affected drastically by the presence of recognized or unrecognized additives
in the sample, including but not limited to colorants, fillers, or low-molecular-weight species.
6. Apparatus
6.1 Volumetric Flasks, 100-mL or other size found convenient.
6.2 Transfer Pipets, sizes between 1 and 25 mL, as required. Transfer pipets for use with polymer solutions should have about
2 mm cut from their lower tips to permit more rapid transfer of the solution to the viscometer.
6.3 Constant-Temperature Bath, capable of maintaining 60.01°C at the desired temperature (usually between 25 and 150°C). Less
stringent temperature control (60.02°C) is satisfactory upon demonstration that the precision of results is not affected.
6.4 Viscometer, glass capillary type, as described in Specifications D446. Efflux time for the solvent and temperature used shall
be greater than 200 s (except that efflux time for semimicro viscometers shall be greater than 80 s), to eliminate the need for kinetic
energy corrections.
6.4.1 Two types of viscometers are commonly used: One is a constant-volume device of simple construction, recommended for
use where solution viscosity is to be measured at a single concentration, as for determination of the reduced viscosity (viscosity
number) or inherent viscosity (logarithmic viscosity number). It may also serve for the determination of the intrinsic viscosity
(limiting viscosity number) through measurement of several solutions having different concentrations.
6.4.2 The second type viscometer, commonly called a dilution viscometer, is a time-saving device for the determination of intrinsic
viscosity (limiting viscosity number) since it does not require constant liquid volume for operation. Several concentrations of a
polymer solution can be tested by adding a known quantity of the solvent at the test temperature directly to the viscometer, mixing,
measuring the viscosity, and then making the next dilution. The viscosity of the pure solvent must be measured separately.
Glassware should conform to the standards of accuracy in National Institute of Standards and Technology Circular No. C602.
D2857 − 22
6.4.3 An alternative procedure is to start with the minimum volume of the pure solvent, then add aliquots of a concentrated stock
solution to the viscometer to obtain values of the relative viscosity (viscosity ratio) at successively higher concentrations. The
choice of procedures is dictated by the range of volumes with which the viscometer will operate and the range of concentrations
desired for test.
6.5 Timer, graduated in divisions of 0.1 s or less, as described in Test Method D445.
6.6 Thermometer, suitable for the specified test temperature and conforming to the specifications of Specification E1E2251,
Kinematic Viscosity Thermometers ASTM 110C (for use at 135°C) and 118C (for use at 30°C).
6.7 Fritted Glass Filter Funnel,Funnel—coarse grade, or equivalent.Funnel, Hirsh-type; borosilicate glass; with coarse fritted disc,
pore size: 40-60 μm.
7. Reagents and Materials
7.1 Solvents, as required, or as recommended in Appendix X1.
7.2 Heat Transfer Liquid, for constant temperature bath.
NOTE 2—The following materials have been used as heat-transfer liquids: (1) silicone oil, (2) mineral oil, (3) peanut oil, (4) water, and (5) water-miscible
liquid, such as glycerin or ethylene glycol. The material selected must not discolor or smoke on prolonged exposure at the test temperature; in some cases
discoloring may be inhibited by the use of an antioxidant. temperature. The use of water or a water-miscible liquid facilitates cleaning glassware used
in the test.
7.3 Nitrogen, for purging.
8. Sample Preparation
8.1 Do not predry or condition the sample unless the material is known to be hygroscopic.
8.2 If it is known that the sample dissolves only slowly in the selected solvent, pretreating the sample to reduce its particle size
may be is advisable.
NOTE 3—Some samples can be pulverized conveniently in a rotary cutting mill with a 20-mesh screen at the outlet of its pulverizing chamber.
(Warning—Take care to avoid overheating the sample during pulverization, which might lead to thermal degradation. Low-melting polymers, or hard,
tough samples, often can be satisfactorily pulverized only at very low temperature as provided by dry ice or liquid nitrogen.)
9. Procedure
9.1 Weigh an appropriate sample into a tared 100-mL volumetric flask (or weigh and transfer quantitatively to the flask). If the
sample is known to oxidize easily in the subsequent dissolution step, the flask may be purged with nitrogen.
NOTE 4—Solution concentrations for some common polymers are recommended in Appendix X1. Since other sizes of volumetric flasks may be used,
depending on the viscometer size and the amount of sample available, adjust sample weights and the so
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