ASTM D7997-15

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 The estimation of precision in this practice is very limited. 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. 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 and health practices and determine the applicability of regulatory limitations prior to use.
Note 1: There is no known ISO equivalent to this standard.

General Information

• Status: Historical
• Publication Date: 14-Nov-2015
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7997 − 15
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 3.2.4 index—the ratio of the equivalents of the isocyanate
component to the equivalents of the resin blend of a polyure-
1.1 This practice covers procedures for determining the gel
thane formulation.
times of polyurethane non-foam formulations using commer-
cially available gel test equipment.
4. Summary of Practice
1.2 Definitions, terms, and techniques are described along
4.1 The gel time of a polyurethane non-foam formulation is
with procedures for calculating sample weights.
determined by measuring the time required for the viscosity of
the polymerizing system to increase to a set level using a gel
1.3 The values stated in SI units are to be regarded as
meter. It is recommended that the torque of the gel meter be
standard. No other units of measurement are included in this
verified with a gauge certified to NIST standards.
standard.
1.4 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 General Utility:
responsibility of the user of this standard to establish appro-
5.1.1 This practice is suitable for research, quality control,
priate safety and health practices and determine the applica-
specification testing and process control.
bility of regulatory limitations prior to use.
5.1.2 It is useful to define and verify the reactivity of
NOTE 1—There is no known ISO equivalent to this standard. non-foam polyurethane formulations.
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.
D883 Terminology Relating to Plastics 5.2.2 The variability of this practice is dependent on the
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
3.2.2 geltime—thetimefromtheinitiationofthereactionto
gel time, and
the gel point. 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
3.2.3 resin blend (formulated polyol)—complete ingredient
measuring wire or spindle of the gel tester from the bottom of
formulation without the isocyanate component.
the container.
5.2.3 The estimation of precision in this practice is very
limited.Usersofthispracticeshalldeveloptheirownprecision
1
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
data to determine if these procedures meet their requirements.
and is the direct responsibility of Subcommittee D20.22 on Cellular Materials -
5.2.4 It is possible that low-levels (ppm, ppb) of contami-
Plastics and Elastomers.
Current edition approved Nov. 15, 2015. Published December 2015. DOI:
nants will not be detected using this practice.
10.1520/D7997–15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6. Sampling
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.1 Since organic isocyanates react with atmospheric
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. moisture, take special precautions in sampling. Usual sampling
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1

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D7997 − 15
methods, even when conducted rapidly, can cause contamina- 9.1.5 Record the gel time.
tion of the sample with insoluble urea. Therefore, blanket the
sample with dry air or nitrogen at all times. (Warning—
10. Sample Calculations
Diisocyanates are eye, skin and respiratory irritants at concen-
10.1 Calculate the equivalent weight, EW , of the resin
p
trations above the occupational exposure limit (TLV or PEL).
blend as follows:
Diisocyanates can cause skin and respirato
...