ASTM D7389-07 (2019) PDF

Full title and description

Standard Test Method for Acid Number (Empirical) of Maleic Anhydride (MAH) Grafted Waxes — ASTM D7389-07(2019). This method specifies a direct-titration procedure and a special sample preparation to determine the free acid (acid number) present in MAH‑grafted waxes, addressing hydrolysis of anhydride functionality that can occur during storage.

Abstract

This short ASTM test method defines the procedure to obtain an empirical acid number for maleic‑anhydride grafted waxes by direct titration with an appropriate titrant after a preparatory step that reverses anhydride hydrolysis. The result is used as a quality‑control measure to quantify free acid content that affects performance and suitability of MAH‑grafted waxes.

General information

• Status: Active (original designation D7389‑07; reapproved 2019).
• Publication date: Reapproval date: January 7, 2019 (original adoption 2007).
• Publisher: ASTM International (ASTM).
• ICS / categories: 75.140 — Waxes, bituminous materials and other petroleum products.
• Edition / version: D7389‑07(2019) — 2007 designation, reapproved in 2019.
• Number of pages: 2.

Scope

This test method covers determination of the acid number (empirical) of maleic anhydride (MAH) grafted waxes. The acid number is obtained by direct titration of the prepared material and indicates the amount of free acid present. A special sample preparation step is included to reverse hydrolysis of the anhydride functionality that can occur during storage, making this procedure specifically applicable to MAH‑grafted waxes rather than to generic wax titration methods. SI units are used as the standard.

Key topics and requirements

• Determination of empirical acid number (mg KOH/g) by direct titration.
• Special sample preparation step to reverse hydrolysis of maleic anhydride moieties prior to titration.
• Applicability limited to MAH‑grafted waxes (standard notes that other wax test methods, e.g., D1386, may be unsuitable for MAH grafted products due to hydrolysis issues).
• Use of SI units; brief method suitable for routine QC and acceptance testing.
• Simple apparatus and reagents; safety and handling notes included by reference to general laboratory practice.

Key method and applicability statements summarized from the ASTM designation.

Typical use and users

Used principally by quality‑control laboratories, product development and R&D teams, and manufacturers or suppliers of MAH‑grafted waxes (polish and coating producers, adhesives, specialty wax formulators). Typical applications include batch acceptance testing, storage stability checks (monitoring hydrolysis/free‑acid formation), and formulation screening where acid functionality affects downstream properties.

Related standards

Related ASTM methods include Test Method D1386 (Acid Number of Synthetic and Natural Waxes), which covers many natural and synthetic waxes but is noted as unsuitable for MAH‑grafted waxes without the special preparation used in D7389. Other D‑series wax test methods and committee D21 guidance on wax testing are also relevant for laboratories establishing comprehensive wax testing protocols.

Keywords

acid number; acid value; maleic anhydride (MAH); MAH‑grafted wax; free acid; titration; sample preparation; hydrolysis; wax QC; ASTM D7389‑07(2019); ICS 75.140.

FAQ

Q: What is this standard?

A: ASTM D7389‑07(2019) is a short ASTM test method that specifies how to determine the empirical acid number of maleic anhydride (MAH) grafted waxes by a direct titration procedure following a preparatory step to reverse anhydride hydrolysis.

Q: What does it cover?

A: It covers the sample preparation and titration steps needed to measure free acid in MAH‑grafted waxes, reporting an acid number that is used for quality control and to assess suitability for intended applications. The method is tailored to address hydrolysis of anhydride groups that can occur during storage.

Q: Who typically uses it?

A: Wax manufacturers, QC laboratories, formulators (polishes, coatings, adhesives), and R&D teams who work with MAH‑grafted wax products and need to monitor free‑acid content.

Q: Is it current or superseded?

A: The designation D7389‑07 was reapproved in 2019 and is listed as active (reapproval date January 7, 2019). For the absolute current status or any revisions after 2019, consult ASTM International for the latest official record.

Q: Is it part of a series?

A: It is part of ASTM's wax testing portfolio developed under committee D21 (wax and related materials). It sits alongside other wax acid‑number methods such as D1386 (for synthetic and natural waxes) but is specific to MAH‑grafted materials.

Q: What are the key keywords?

A: Acid number, maleic anhydride, MAH‑grafted wax, free acid, titration, hydrolysis, wax QC, D7389.