ASTM D2024-09

This document is not anASTM standard and is intended only to provide the user of anASTM 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:D2024–65 (Reapproved 2003) Designation: D2024 – 09
Standard Test Method for
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Cloud Point of Nonionic Surfactants
This standard is issued under the fixed designation D2024; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope
1.1This test method covers the determination of the solubility inversion temperature or “cloud point” of nonionic surfactants or
detergent systems which are characteristically less soluble in water at higher temperatures than at lower temperatures. It is limited
to those surfactants and detergent systems for which the visible solubility change occurs over a range of 1°C or less at
concentrations of 0.5 to 1.0 % in water between 30 and 95°C.
1.1 This test method covers a procedure to determine the “cloud point” of nonionic surfactants or detergent systems. Cloud
Pointisthetemperatureatwhichdissolvedcomponents(solidsorliquids)arenolongercompletelysoluble,precipatingasasecond
phase giving the fluid a cloudy appearance. It is limited to those surfactants and detergent systems for which the visible solubility
change occurs over a range of 1°C or less at concentrations of 0.5 to 1.0 % in DI water between 30 and 95°C.
1.2 Chemical Limitations—Nonionic surfactants that exhibit a characteristic cloud point in general terms consist of a
water-in-soluble moiety condensed with 50 to 75 % by weight of ethylene oxide. —Nonionic surfactants that exhibit a
characteristic cloud point in general terms consist of a water-in-soluble moiety condensed with 50 to 75 % by weight of ethylene
oxide. If the level of ethoxylation is too low the surfactant may not be water soluble at temperatures less than 30°C, and if it is
too high no cloud point may exist.
1.3 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
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2.1 ASTM Standards:
E1 Specification for ASTM Liquid-in-Glass Thermometers
3. Significance and Use
3.1 The cloud point temperature is a reproducible characteristic of certain pure nonionic surfactants. It is also characteristic of
certain nonionic surfactant formulated systems. This test method is appropriate for both systems.
NOTE 1—Ifthetransitionfromadistinctlycloudytoaclearsolutionisnotsharp,thatis,ifitdoesnottakeplacewithinarangeof1°C,thistestmethod
is not appropriate.
4. Interferences
4.1 Ionic surfactants or detergents in concentrations down to1%or less of the nonionic surfactant drastically raise the
characteristic cloud point of the latter. The presence of salts and bases (that is, non-surface active materials) will lower the
characteristic cloud point. Acidspoint, while acids tend to raise the cloud point.
5. Apparatus
5.1 Thermometer—An ASTM Partial Immersion Thermometer having a range from−20 to+150°C or 0 to 302°F and
conforming to the requirements for Thermometer 1C or 1F in accordance with Specification E1.
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This test method is under the jurisdiction ofASTM Committee D12 on Soaps and Other Detergents and is the direct responsibility of Subcommittee D12.15 on Physical
Testing.
Current edition approved Aug. 31, 1965. Published October 1965. Originally published as D2024–62T. Last previous edition D2024–62T. DOI: 10.1520/D2024-65R03.
Current edition approved Oct. 1, 2009. Published November 2009. Originally approved in 1962 as D2024–62T. Last previous edition approved in 2003 as
D2024–65(2003). DOI: 10.1520/D2024-09.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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D2024 – 09
6. Procedure
6.1Prepare a 1.0 % test solution by weighing a 1 6 0.1-g sample into a 150-mL beaker and add 100 mL of distilled or
demineralized water which is at a temperature of less than 30°C. Agitate until the sample is dissolved. Pour 50 6 5 mL of te
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