ASTM D4640-86(2022)

Standard Test Method for Determining Stroke Cure Time of Thermosetting Phenol-Formaldehyde Resins

SIGNIFICANCE AND USE
4.1 This method is significant as a process control for polymerization time.  
4.2 When the cure times are determined at several temperatures and plotted as time versus temperature, different resins can be compared for curing characteristics.
SCOPE
1.1 This test method covers the determination of the cure rate at any specified temperature for a thermosetting phenol-formaldehyde resin. The time at that temperature required to make a fluid mixture change into a hard immovable mass indicates speed of cure.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
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.  
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-May-2022
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.33 - Polymers and Resins

Overview

ASTM D4640-86(2022), Standard Test Method for Determining Stroke Cure Time of Thermosetting Phenol-Formaldehyde Resins, is an internationally recognized test method established by ASTM International. This standard covers the determination of the cure rate for thermosetting phenol-formaldehyde resins at specified temperatures. The stroke cure time represents the interval required for a fluid phenol-formaldehyde mixture to transform into a hardened, immovable mass under controlled test conditions. The method is significant for process control and quality assurance in industries using these resins, providing a reliable metric for polymerization speed and consistency.

Key Topics

• Cure Rate Determination: This test method measures the time, at a specified temperature, required for phenol-formaldehyde resin to transition from a liquid to a solid, non-movable state. The result indicates the speed of cure, critical for process optimization.
• Comparative Analysis: By performing the test at various temperatures and plotting time versus temperature, manufacturers can compare different resin formulations for curing characteristics, aiding in selection and development.
• Process Control: The stroke cure time serves as a process control parameter during manufacturing, enabling real-time monitoring and adjustment to ensure product quality.
• Test Procedure: The procedure involves spreading a small quantity of resin on a heated, smooth surface and stroking it with a spatula until the material no longer adheres. The elapsed time is recorded as the stroke cure time.
• Unit Standards: Results are reported in inch-pound units, with SI conversions provided for informational purposes.

Applications

ASTM D4640-86(2022) is widely used in various industries where thermosetting phenol-formaldehyde resins play a key role, including:

• Manufacturing of Laminates and Molding Compounds: Ensures resins reach the proper state of cure for durability and performance.
• Quality Assurance Laboratories: Enables comparison of resin batches and verification of supplier specifications.
• Research and Development: Supports formulation development and performance optimization by evaluating curing characteristics.
• Process Engineering: Provides data for adjusting cure cycles in production processes, minimizing defects and improving efficiency.
• Technical Specification Compliance: Allows resin manufacturers and users to document and confirm compliance with curing requirements for safety and performance.

By implementing this standard, organizations can ensure consistent resin performance, improved process reliability, and product quality, as well as easier troubleshooting in resin-cure related issues.

Related Standards

Understanding the context and complementary documents can benefit those using ASTM D4640-86(2022). Relevant related standards include:

• ASTM D1151 - Standard Test Method for Effect of Moisture and Temperature on Adhesive Bonds
• ASTM D1583 - Standard Test Methods for Phenolic Resins
• ASTM D3310 - Standard Test Method for Determining the Gel Time of Thermosetting Coating Powders
• ISO 3673 - Plastics-Epoxy Resins-Determination of Epoxy Equivalent and Hydroxyl Content

By referencing ASTM D4640-86(2022) along with these related standards, professionals in coatings, adhesives, and composite industries can achieve robust quality management and compliance, streamline R&D efforts, and enhance the reliability of their phenol-formaldehyde resin products. For further information, consult the ASTM International website or related technical committees involved in polymer and resin standardization.

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: D4640 − 86 (Reapproved 2022)
Standard Test Method for
Determining Stroke Cure Time of Thermosetting Phenol-
Formaldehyde Resins
This standard is issued under the fixed designation D4640; 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 4.2 When the cure times are determined at several tempera-
tures and plotted as time versus temperature, different resins
1.1 This test method covers the determination of the cure
can be compared for curing characteristics.
rate at any specified temperature for a thermosetting phenol-
formaldehyde resin. The time at that temperature required to
5. Apparatus
make a fluid mixture change into a hard immovable mass
indicates speed of cure.
5.1 Electric Hot Cure Plate, with a smooth surface free of
rough spots with adjustable control to hold the temperature
1.2 The values stated in inch-pound units are to be regarded
within 3.5 °F (2 °C) (Note 1).
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only 7
5.2 Spatula,3by ⁄16 in. (75 by 10 mm), stainless.
and are not considered standard.
5.3 Stopwatch.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 5.4 Knife, brass, putty with straight edge.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 6. Procedure
mine the applicability of regulatory limitations prior to use.
6.1 Adjust the hot plate to the desired test temperature.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard- NOTE 1—Usual temperatures are 300 °F (150 °C), 320 °F (160 °C), and
330 °F (165 °C).
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
6.2 Place an approximately 0.5-g specimen on the hot plate
2 2
mendations issued by the World Trade Organization Technical
and spread over an approximately 2-in. (130-mm ) area with
Barriers to Trade (TBT) Committee.
a clean spatula as quickly as possible. Start the stopwatch
immediately upon adding the specimen to the hot plate, then
2. Terminology
stroke steadily across the specimen in alternating smoothing
2.1 Definitions of Terms Specific to This Standard:
and patting motions.
2.1.1 stroke cure time, n—the time required for a resin being
6.3 As the resin approaches the cured stage, it becomes
held at a specified temperature on a hot plate and being stroked
more viscous and stringy. Stop the stopwatch when the resin on
with a spatula, to adhere to the hot plate and not to the spatula.
the hot plate a
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