ASTM D3312-18

Standard Test Method for Percent Reactive Monomer in Solventless Varnishes

SIGNIFICANCE AND USE
4.1 The percent of reactive monomer in solventless varnishes will affect the viscosity, the handling, and the processing properties of the uncured resin. The percent of reactive monomer will possibly affect the degree of hardness and shrinkage which in turn will affect the physical and electrical properties of the cured resin.
SCOPE
1.1 This test method covers the determination of the percent of volatile reactive monomer having a vapor pressure exceeding 13.3 Pa (0.1 Torr) at 25°C in an uncatalyzed solventless varnish. Experience has shown this method does not accurately determine percent reactive monomer when the vapor pressure is less than 13.3 Pa (0.1 Torr).  
1.2 The values stated in SI units are the standard. The values given in parentheses are for information only.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For a specific precaution, see Section 5.
Note 1: There is no similar or equivalent ISO/IEC standard.  
1.4 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: 31-Oct-2018
• ICS: 87.040 - Paints and varnishes
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.01 - Electrical Insulating Products

Relations

• Replaces: ASTM D3312-04(2013) - Standard Test Method for Percent Reactive Monomer in Solventless Varnishes
• Effective Date: 01-Nov-2018
• Refers: ASTM D1711-24 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Mar-2024
• Refers: ASTM D1711-15 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2015
• Refers: ASTM D1711-14a - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2014
• Refers: ASTM D1711-14 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-May-2014
• Refers: ASTM D1711-13 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2013
• Refers: ASTM D1711-11a - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Aug-2011
• Refers: ASTM D1711-08 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-May-2008
• Refers: ASTM D5423-93(2005) - Standard Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation (Withdrawn 2014)
• Effective Date: 01-Sep-2005
• Refers: ASTM D1711-02 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 10-Mar-2002
• Refers: ASTM D1711-99 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 10-Oct-1999
• Refers: ASTM D5423-93(1999) - Standard Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D1711-22 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2018
• Referred By: ASTM D4733-17 - Standard Test Methods for Solventless Electrical Insulating Varnishes
• Effective Date: 01-Nov-2018

Overview

ASTM D3312-18: Standard Test Method for Percent Reactive Monomer in Solventless Varnishes provides a recognized procedure for determining the percentage of volatile reactive monomer in uncatalyzed solventless varnishes. This test method is particularly relevant where the monomer's vapor pressure exceeds 13.3 Pa (0.1 Torr) at 25°C, as lower vapor pressures may not yield accurate results. Published by ASTM International, the standard supports manufacturers, laboratories, and quality control operations in evaluating key chemical and physical properties affecting varnish performance.

Reactive monomer content directly impacts handling, viscosity, processing, and ultimately the cured resin's hardness, shrinkage, and insulating properties. Accurate determination is crucial for ensuring consistent product characteristics in electrical insulation, coatings, and related applications.

Key Topics

• Reactive Monomer Definition: In solventless electrical varnishes, a reactive monomer is a substance that combines chemically with the resin under specified conditions, influencing the varnish's behavior before and after curing.
• Test Applicability: The method is valid only for solventless varnishes with volatile monomer vapor pressures above 13.3 Pa (0.1 Torr) at 25°C.
• Specimen Preparation and Testing:
  • Use precise balances and forced-draft ovens as outlined in referenced ASTM standards.
  • Dilution and mixing carried out in controlled conditions to minimize loss of materials.
  • Calculation of percent monomer is based on the weight loss after drying.
• Result Relevance: The percentage of reactive monomer correlates with key processing properties (e.g., viscosity, ease of handling) and impacts the physical and electrical characteristics of the cured varnish.
• Precision and Bias: The method's interlaboratory standard deviation is well documented for common monomers, ensuring reliability. The process is unbiased as results are based solely on measurement data.
• Safety Considerations: Testing involves heating flammable materials, necessitating appropriate precautions such as adequate ventilation and proper storage.

Applications

The ASTM D3312-18 test method is applied across a range of industries where solventless varnishes are used, specifically in:

• Electrical Insulation: Ensuring that insulating varnishes used in electrical equipment meet required performance metrics for dielectric strength and durability.
• Resin Formulation: Assisting formulation chemists in maintaining consistent physical and chemical properties in formulations for coatings, adhesives, and encapsulants.
• Quality Control and Compliance: Supporting batch-to-batch consistency, troubleshooting production issues, and verifying product specifications for manufacturers.
• Research and Development: Facilitating studies aimed at the innovation of new solventless varnish systems with optimized curing and performance characteristics.

Understanding the percent reactive monomer is vital for managing the processability of uncured varnish, as well as forecasting properties such as hardness and shrinkage in the final cured material.

Related Standards

For enhanced utility and alignment in laboratory settings, the following ASTM standards are commonly referenced with D3312-18:

• ASTM D1711: Terminology Relating to Electrical Insulation, providing definitions pertinent to the industry.
• ASTM D5423: Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation, detailing required equipment for conducting this test method.

At the time of publication, there are no similar or equivalent ISO/IEC standards for this specific test method.

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Keywords: ASTM D3312-18, percent reactive monomer, solventless varnishes, test method, electrical insulation, varnish formulation, resin properties, quality control, laboratory testing, volatile monomer content.

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: D3312 − 18
Standard Test Method for
Percent Reactive Monomer in Solventless Varnishes
This standard is issued under the fixed designation D3312; 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* 3.1.1 reactive monomer, n—in solventless electrical varnish,
a substance, that, when added to a resin, will combine
1.1 This test method covers the determination of the percent
chemically with that resin under specified conditions.
of volatile reactive monomer having a vapor pressure exceed-
3.2 See Terminology D1711 for definitions of other terms
ing 13.3 Pa (0.1 Torr) at 25°C in an uncatalyzed solventless
relating to electrical insulation.
varnish. Experience has shown this method does not accurately
determine percent reactive monomer when the vapor pressure
4. Significance and Use
is less than 13.3 Pa (0.1 Torr).
4.1 The percent of reactive monomer in solventless var-
1.2 ThevaluesstatedinSIunitsarethestandard.Thevalues
nisheswillaffecttheviscosity,thehandling,andtheprocessing
given in parentheses are for information only.
properties of the uncured resin. The percent of reactive
1.3 This standard does not purport to address all of the
monomer will possibly affect the degree of hardness and
safety concerns, if any, associated with its use. It is the
shrinkage which in turn will affect the physical and electrical
responsibility of the user of this standard to establish appro-
properties of the cured resin.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
5. Safety Precautions
For a specific precaution, see Section 5.
5.1 It is unsafe to use varnish at temperatures above the
flash point without adequate ventilation, especially if the
NOTE 1—There is no similar or equivalent ISO/IEC standard.
possibility exists that flames or sparks are present. Store
1.4 This international standard was developed in accor-
varnish in sealed containers.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
6. Apparatus
Development of International Standards, Guides and Recom-
6.1 Balance, capable of weighing to nearest 0.0001 g.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
6.2 Thermometer—A glass thermometer having a range
from 0 to 200°C (30 to 400°F) and accurate within 61°C
2. Referenced Documents
(62°F).
2.1 ASTM Standards:
6.3 Oven—A forced-draft constant-temperature oven con-
D1711 Terminology Relating to Electrical Insulation forming to Specification D5423, Type II.
D5423 Specification for Forced-Convection Laboratory Ov-
6.4 Bottle and Drying Dishes—A stoppered bottle and
ens for Evaluation of Electrical Insulation
flat-bottomaluminumdryingdish.havinganinsidediameterof
3 5
approximately 70 mm (2 ⁄4 in.) and a depth of 8 mm ( ⁄16 in.).
3. Terminology
6.5 Desiccator—Asuitable desiccator containing anhydrous
3.1 Definitions of Terms Specific to This Standard:
calcium chloride (CaCl ).
7. Test Specimens
This test method is under the jurisdiction of ASTM Committee D09 on
7.1 Preparing Specimens—Place a portion of the uncata-
Electrical and Electronic Insulating Materials and is the direct responsibility of
lyzed solventless varnish in a stoppered bottle and weigh.
Subcommittee D09.01 on Electrical Insulating Products.
Transfer a specimen weighing between 0.2 and 0.3 g from the
Current edition approved Nov. 1, 2018. Published November 2018. Originally
weighed stoppered bottle to a weighed drying dish, which has
approved in 1974. Last previous edition approved in 2013 as D3312 – 04 (2013).
DOI: 10.1520/D3312-18.
beenpreviouslyheatedfor30minat150°C(300°F)andcooled
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
...

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: D3312 − 04 (Reapproved 2013) D3312 − 18
Standard Test Method for
Percent Reactive Monomer in Solventless Varnishes
This standard is issued under the fixed designation D3312; 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 test method covers the determination of the percent of volatile reactive monomer having a vapor pressure exceeding
13.3 Pa (0.1 Torr) at 25°C in an uncatalyzed solventless varnish. Experience has shown this method does not accurately determine
percent reactive monomer when the vapor pressure is less than 13.3 Pa (0.1 Torr).
1.2 The values stated in SI units are the standard. The values given in parentheses are for information only.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For a specific precaution, see Section 5.
NOTE 1—There is no similar or equivalent ISO/IEC standard.
1.4 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:
D1711 Terminology Relating to Electrical Insulation
D5423 Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 reactive monomer, n—in solventless electrical varnish, a substance, that, when added to a resin, will combine chemically
with that resin under specified conditions.
3.2 See Terminology D1711 for definitions of other terms relating to electrical insulation.
4. Significance and Use
4.1 The percent of reactive monomer in solventless varnishes will affect the viscosity, the handling, and the processing
properties of the uncured resin. The percent of reactive monomer will possibly affect the degree of hardness and shrinkage which
in turn will affect the physical and electrical properties of the cured resin.
5. Safety Precautions
5.1 It is unsafe to use varnish at temperatures above the flash point without adequate ventilation, especially if the possibility
exists that flames or sparks are present. Store varnish in sealed containers.
6. Apparatus
6.1 Balance, capable of weighing to nearest 0.0001 g.
6.2 Thermometer—A glass thermometer having a range from 0 to 200°C (30 to 400°F) and accurate within 61°C (62°F).
This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.01 on Electrical Insulating Varnishes, Powders and Encapsulating CompoundsProducts.
Current edition approved April 1, 2013Nov. 1, 2018. Published April 2013November 2018. Originally approved in 1974. Last previous edition approved in 20092013 as
D3312 – 04 (2009).(2013). DOI: 10.1520/D3312-04R13.10.1520/D3312-18.
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
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D3312 − 18
6.3 Oven—A forced-draft constant-temperature oven conforming to Specification D5423, Type II.
6.4 Bottle and Drying Dishes—A stoppered bottle and fla
...