ASTM D7997-21

Standard Practice for Polyurethane Raw Materials: Gel Tests for Polyurethane Non-Foam Formulations

SIGNIFICANCE AND USE
5.1 General Utility:  
5.1.1 This practice is suitable for research, quality control, specification testing and process control.  
5.1.2 It is useful to define and verify the reactivity of non-foam polyurethane formulations.  
5.2 Limitations:  
5.2.1 Operator-to-operator variability and lab-to-lab variability can be significant.  
5.2.2 The variability of this practice is dependent on the equipment used to measure the gel time. It is recommended that the testing laboratory and the client agree on the equipment and the conditions to be used that include the following:
5.2.2.1 Gel Tester and gel point criteria,
5.2.2.2 Speed/rpm of the mixer,
5.2.2.3 Type and shape of the mix blades,
5.2.2.4 Size and type (for example, shape, lined or unlined) of container for mixing the components and for measuring the gel time, and
5.2.2.5 The volume (or height) of material to be placed in the container for measuring the gel time and the depth of the measuring wire or spindle of the gel tester from the bottom of the container.  
5.2.3 Users of this practice shall develop their own precision data to determine if these procedures meet their requirements.  
5.2.4 It is possible that low-levels (ppm, ppb) of contaminants will not be detected using this practice.
SCOPE
1.1 This practice covers procedures for determining the gel times of polyurethane non-foam formulations using commercially available gel test equipment.  
1.2 Definitions, terms, and techniques are described along with procedures for calculating sample weights.  
1.3 The values stated in SI units are to be regarded as standard.  
1.4 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: There is no known ISO equivalent to this standard.  
1.5 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: 14-Jan-2021
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

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: D7997 − 21
Standard Practice for
Polyurethane Raw Materials: Gel Tests for Polyurethane
1
Non-Foam Formulations
This standard is issued under the fixed designation D7997; 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 3.2.2 geltime—thetimefromtheinitiationofthereactionto
the gel point.
1.1 This practice covers procedures for determining the gel
3.2.3 resin blend (formulated polyol)—complete ingredient
times of polyurethane non-foam formulations using commer-
formulation without the isocyanate component.
cially available gel test equipment.
3.2.4 index—the ratio of the equivalents of the isocyanate
1.2 Definitions, terms, and techniques are described along
component to the equivalents of the resin blend of a polyure-
with procedures for calculating sample weights.
thane formulation.
1.3 The values stated in SI units are to be regarded as
standard.
4. Summary of Practice
1.4 This standard does not purport to address all of the
4.1 The gel time of a polyurethane non-foam formulation is
safety concerns, if any, associated with its use. It is the
determined by measuring the time required for the viscosity of
responsibility of the user of this standard to establish appro-
the polymerizing system to increase to a set level using a gel
priate safety, health, and environmental practices and deter-
meter. It is recommended that the torque of the gel meter be
mine the applicability of regulatory limitations prior to use.
verified with a gauge certified to NIST standards.
NOTE 1—There is no known ISO equivalent to this standard.
5. Significance and Use
1.5 This international standard was developed in accor-
5.1 General Utility:
dance with internationally recognized principles on standard-
5.1.1 This practice is suitable for research, quality control,
ization established in the Decision on Principles for the
specification testing and process control.
Development of International Standards, Guides and Recom-
5.1.2 It is useful to define and verify the reactivity of
mendations issued by the World Trade Organization Technical
non-foam polyurethane formulations.
Barriers to Trade (TBT) Committee.
5.2 Limitations:
2. Referenced Documents
5.2.1 Operator-to-operator variability and lab-to-lab vari-
2
2.1 ASTM Standards: ability can be significant.
5.2.2 The variability of this practice is dependent on the
D883 Terminology Relating to Plastics
equipment used to measure the gel time. It is recommended
3. Terminology
thatthetestinglaboratoryandtheclientagreeontheequipment
and the conditions to be used that include the following:
3.1 Definitions—Forgeneraldefinitionsoftermsusedinthis
5.2.2.1 Gel Tester and gel point criteria,
practice see Terminology D883.
5.2.2.2 Speed/rpm of the mixer,
3.2 Definitions of Terms Specific to This Standard:
5.2.2.3 Type and shape of the mix blades,
3.2.1 gel point—the extent of polymerization at which the
5.2.2.4 Size and type (for example, shape, lined or unlined)
upper limit, as defined by the procedure being run, is reached.
of container for mixing the components and for measuring the
gel time, and
1
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
5.2.2.5 The volume (or height) of material to be placed in
and is the direct responsibility of Subcommittee D20.22 on Cellular Materials -
the container for measuring the gel time and the depth of the
Plastics and Elastomers.
measuring wire or spindle of the gel tester from the bottom of
Current edition approved Jan. 15, 2021. Published January 2021. Originally
the container.
approved in 2015. Last previous edition approved in 2015 as D7997 - 15. DOI:
10.1520/D7997–21.
5.2.3 Usersofthispracticeshalldeveloptheirownprecision
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
data to determine if these procedures meet their requirements.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.2.4 It is possible that low-levels (ppm, ppb) of contami-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. nants will not be detected using this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7997 − 21
6. Sampling 9.1.4 Stop the timer when the reaction reaches the gel point.
Many commercial units will shut off automatically at the
6.1 Sinc
...

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: D7997 − 15 D7997 − 21
Standard Practice for
Polyurethane Raw Materials: Gel Tests for Polyurethane
1
Non-Foam Formulations
This standard is issued under the fixed designation D7997; 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
1.1 This practice covers procedures for determining the gel times of polyurethane non-foam formulations using commercially
available gel test equipment.
1.2 Definitions, terms, and techniques are described along with procedures for calculating sample weights.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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—There is no known ISO equivalent to this standard.
1.5 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
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
3. Terminology
3.1 Definitions—For general definitions of terms used in this practice see Terminology D883.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 gel point—the extent of polymerization at which the upper limit, as defined by the procedure being run, is reached.
3.2.2 gel time—the time from the initiation of the reaction to the gel point.
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Materials - Plastics
and Elastomers.
Current edition approved Nov. 15, 2015Jan. 15, 2021. Published December 2015January 2021. Originally approved in 2015. Last previous edition approved in 2015 as
D7997 - 15. DOI: 10.1520/D7997–15.10.1520/D7997–21.
2
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7997 − 21
3.2.3 resin blend (formulated polyol)—complete ingredient formulation without the isocyanate component.
3.2.4 index—the ratio of the equivalents of the isocyanate component to the equivalents of the resin blend of a polyurethane
formulation.
4. Summary of Practice
4.1 The gel time of a polyurethane non-foam formulation is determined by measuring the time required for the viscosity of the
polymerizing system to increase to a set level using a gel meter. It is recommended that the torque of the gel meter be verified with
a gauge certified to NIST standards.
5. Significance and Use
5.1 General Utility:
5.1.1 This practice is suitable for research, quality control, specification testing and process control.
5.1.2 It is useful to define and verify the reactivity of non-foam polyurethane formulations.
5.2 Limitations:
5.2.1 Operator-to-operator variability and lab-to-lab variability can be significant.
5.2.2 The variability of this practice is dependent on the equipment used to measure the gel time. It is recommended that the testing
laboratory and the client agree on the equipment and the conditions to be used that include the following:
5.2.2.1 Gel Tester and gel point criteria,
5.2.2.2 Speed/rpm of the mixer,
5.2.2.3 Type and shape of the mix blades,
5.2.2.4 Size and type (for example, shape, lined or unlined) of container for mixing the components and for measuring the gel
time, and
5.2.2.5 The volume (or height) of material to be placed in the container for measuring the gel time and the depth of the measuring
wire or spindle of the gel tester from the bottom of the container.
5.2.3 The estimation of precision in this practice is very limited. Users of this practice shall develop
...