ASTM D7389-07(2019)

Standard Test Method for Acid Number (Empirical) of Maleic Anhydride (MAH) Grafted Waxes

SIGNIFICANCE AND USE
4.1 This test method is used to determine the free acid content of MAH-grafted waxes. The potential hydrolysis of the anhydride functionality of this wax in storage makes them unsuitable for determining free acid content by Test Method D1386. Free acid content is a significant quality control test, and is a determinant of the utility of the wax.
SCOPE
1.1 This test method covers the determination of the acid number of maleic anhydride (MAH) grafted waxes. The number is obtained by direct titration of the material and indicates the amount of free acid present.  
1.2 This test method is applicable to MAH-grafted waxes because it uses a special sample preparation step (7.1) that is not required for other waxes. The special sample preparation reverses the hydrolysis of acid anhydride that can occur during storage of the wax.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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: 30-Jun-2019
• ICS: 75.140 - Waxes, bituminous materials and other petroleum products
• Technical Committee: D21 - Polishes
• Drafting Committee: D21.02 - Raw Materials

Relations

• Replaces: ASTM D7389-07(2012) - Standard Test Method for Acid Number (Empirical) of Maleic Anhydride (MAH) Grafted Waxes
• Effective Date: 01-Jul-2019
• Refers: ASTM D1386-10 - Standard Test Method for Acid Number (Empirical) of Synthetic and Natural Waxes
• Effective Date: 01-May-2010
• Refers: ASTM D1386-98(2004) - Standard Test Method for Acid Number (Empirical) of Synthetic and Natural Waxes
• Effective Date: 01-Sep-2004
• Refers: ASTM D1386-98 - Standard Test Method for Acid Number (Empirical) of Synthetic and Natural Waxes
• Effective Date: 10-Sep-1998

Overview

ASTM D7389-07(2019) is the standard test method for determining the acid number (empirical) of maleic anhydride (MAH) grafted waxes. This method is specifically designed to measure the free acid content of MAH-grafted waxes, addressing issues related to the hydrolysis of anhydride functionalities that can occur during storage. The acid number, expressed in milligrams of potassium hydroxide needed to neutralize 1 gram of sample, serves as a crucial quality control parameter for producers and users of MAH-grafted waxes, ensuring product consistency and performance.

Key Topics

• Purpose of the Standard: The primary intent is to determine the acid number for MAH-grafted waxes by direct titration, providing quantitative data on free acid content.
• Importance for Quality Control: The acid number is significant for assessing the utility and suitability of waxes in various applications. Consistent acid values indicate proper manufacturing and storage conditions.
• Special Sample Preparation: Due to possible hydrolysis of the anhydride group during storage, a unique sample preparation step is included to reverse this reaction and deliver reliable acid number measurement.
• Application to MAH-Grafted Waxes Only: This method is specifically tailored for MAH-modified waxes. Other waxes should be tested using different methods, such as ASTM D1386, as the chemistry and stability differ.
• Testing Precision and Accuracy: The standard establishes guidelines for ensuring reproducible results, indicating that duplicate tests by the same operator should not differ by more than a defined standard deviation.

Applications

The acid number determination outlined in ASTM D7389-07(2019) is applied in several important scenarios:

• Manufacturing Quality Assurance: Producers of MAH-grafted waxes use this test to routinely verify free acid content, maintaining consistent product properties and identifying deviations in processing or storage.
• Raw Material Evaluation: Buyers and users of MAH-grafted waxes rely on acid number data for material acceptance and suitability assessments.
• Polish and Synthetic Wax Industries: The test supports quality control for waxes used in polishes, coatings, and related synthetic wax applications, where acid value can impact final product characteristics such as gloss, durability, and chemical resistance.
• Research and Development: R&D laboratories use this method when formulating new wax types or modifying existing materials to ensure intended chemical functionality.

Benefits:

• Accurate measurement of free acid content in MAH-grafted waxes
• Enhanced quality control and assurance for both manufacturers and end-users
• Reliable data for regulatory compliance and material specifications

Related Standards

• ASTM D1386 - Test Method for Acid Number (Empirical) of Synthetic and Natural Waxes: Applicable to non-MAH-grafted waxes, using different sample preparations.
• ASTM E200 - Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis: Referenced for reagent preparation and laboratory best practices.

Keywords: acid number, acid value, free acid, MAH-grafted waxes, titration, wax quality control, synthetic waxes, ASTM D7389, analytical chemistry standards

By implementing ASTM D7389-07(2019), laboratories and manufacturers can ensure reliable acid number determination for MAH-grafted waxes, supporting quality, consistency, and compliance within the chemical, plastics, and wax industries.

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: D7389 − 07 (Reapproved 2019)
Standard Test Method for
Acid Number (Empirical) of Maleic Anhydride (MAH) Grafted
Waxes
This standard is issued under the fixed designation D7389; 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. Terminology
3.1 Definitions:
1.1 This test method covers the determination of the acid
3.1.1 acid number or acid value—the number of milligrams
number of maleic anhydride (MAH) grafted waxes. The
of potassium hydroxide necessary to neutralize1gofthe
number is obtained by direct titration of the material and
sample.
indicates the amount of free acid present.
1.2 This test method is applicable to MAH-grafted waxes
4. Significance and Use
because it uses a special sample preparation step (7.1) that is
4.1 This test method is used to determine the free acid
not required for other waxes. The special sample preparation
content of MAH-grafted waxes.The potential hydrolysis of the
reverses the hydrolysis of acid anhydride that can occur during
anhydride functionality of this wax in storage makes them
storage of the wax.
unsuitable for determining free acid content by Test Method
1.3 The values stated in SI units are to be regarded as
D1386. Free acid content is a significant quality control test,
standard. No other units of measurement are included in this
and is a determinant of the utility of the wax.
standard.
1.4 This standard does not purport to address all of the
5. Apparatus
safety concerns, if any, associated with its use. It is the
5.1 Analytical Balance.
responsibility of the user of this standard to establish appro-
5.2 Buret, 50-mL, with 0.1-mL graduations.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
5.3 Flasks, acid value, 250-mL.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
6. Reagents and Materials
ization established in the Decision on Principles for the
6.1 Purity of Reagents—Reagent-grade chemicals or
Development of International Standards, Guides and Recom-
equivalent, as specified in Practice E200, shall be used in all
mendations issued by the World Trade Organization Technical
tests.
Barriers to Trade (TBT) Committee.
6.2 Ethanolic Potassium Hydroxide, Standard Solution (0.1
N)—Dissolve 6.6 g of potassium hydroxide in 5.6 g of distilled
2. Referenced Documents
water. Dilute with USSD3Adenatured ethanol or 95 % ethanol
2.1 ASTM Standards:
to 1000 mL. Standardize with 0.1 N hydrochloric acid.
D1386 Test Method for Acid Number (Empirical) of Syn-
6.3 Phenolphthalein Indicator Solution (10 g/litre)—
thetic and Natural Waxes
Dissolve1gof phenolphthalein in 100 mL of USSD3A,
E200 Practice for Preparation, Standardization, and Storage
denatured ethanol or 95 % ethanol.
of Standard and Reagent Solutions for ChemicalAnalysis
6.4 Xylene.
7. Sample Preparation
This test method is under the jurisdiction ofASTM Committee D21 on Polishes
and is the direct responsibility of Subcommittee D21.02 on Raw Materials.
7.1 Melt20gofthesamplewaxina250-mLflaskorbeaker
Current edition approved July 1, 2019. Published July 2019. Originally approved
and heat to 180–190°C. Apply a slight vacuum as the wax
in 2007. La
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