ASTM D7977-23 PDF

Full title and description

ASTM D7977-23 — Standard Test Methods for Polymer Content of AMS (α‑Methylstyrene). This document describes validated laboratory procedures for determining the concentration of polymer (insoluble polymer particles) in α‑methylstyrene (AMS) monomer, intended for use in plant control, specification testing and quality assurance of AMS production and handling.

Abstract

ASTM D7977-23 specifies spectrophotometric test procedures that measure turbidity produced when dry methanol is added to an AMS sample (polymeric material is insoluble in methanol). The method is applicable up to about 15 mg/kg polymer in AMS with a reported limit of quantitation (LOQ) of ~0.6 mg/kg and limit of detection (LOD) of ~0.2 mg/kg; samples with polymer >15 mg/kg must be diluted prior to analysis. The method does not detect dimers and trimers and is intended for plant control and specification analysis.

General information

• Status: Active.
• Publication date: April 1, 2023 (edition D7977‑23).
• Publisher: ASTM International (ASTM).
• ICS / categories: 71.080.15 (Aromatic hydrocarbons).
• Edition / version: D7977‑23 (current 2023 edition; replaces earlier D7977 editions).
• Number of pages: 4 pages.

Scope

This standard covers determination of polymer content in AMS (α‑methylstyrene) monomer by methods that produce and measure turbidity after the addition of dry methanol (Test Method A: spectrophotometric turbidity measurement). The method reports applicable concentration range up to ~15 mg/kg, with an LOQ of about 0.6 mg/kg and an LOD of about 0.2 mg/kg; samples exceeding the upper range must be diluted. The standard specifies rounding rules per Practice E29 and notes that dimers and trimers are not measured by these procedures. Safety, health and environmental considerations are left to the user (see Section 8 of the standard).

Key topics and requirements

• Principle: polymer present as insoluble particulate in AMS is precipitated/isolated by addition of dry methanol and quantified by measuring turbidity (spectrophotometer).
• Applicable range: validated up to ~15 mg/kg polymer in AMS; LOQ ≈ 0.6 mg/kg; LOD ≈ 0.2 mg/kg.
• Sample handling: samples >15 mg/kg must be diluted before measurement; follow Practice E29 for rounding results.
• Limitations: method does not detect oligomers such as dimers and trimers.
• Use cases: plant process control, incoming material checks, specification verification for AMS.
• Metadata: published DOI 10.1520/D7977-23; developed by ASTM Committee D16 and Subcommittee D16.07.

Typical use and users

Primary users are analytical and QA/QC laboratories in petrochemical and specialty chemical manufacturers producing or using α‑methylstyrene (AMS), process control engineers, specification writers, and regulatory or inspection bodies that need a repeatable method for polymer-content checks in AMS monomer. Research laboratories working on monomer purity and product development may also use the method for comparability and validation studies.

Related standards

ASTM D7977-23 is related to other ASTM documents for styrenic monomers and specifications — for example, ASTM D6367 (specification and related test methods for AMS) and earlier editions of D7977 (D7977‑19, D7977‑14). The document sits in Book of Standards volume 06.04 alongside other test methods for styrenic and aromatic hydrocarbons.

Keywords

α‑methylstyrene; AMS; polymer content; turbidity; spectrophotometric test; LOQ; LOD; D7977; ASTM D7977‑23.

FAQ

Q: What is this standard?

A: ASTM D7977‑23 is a short test-method standard that specifies procedures to determine the polymer (insoluble particulate) content of α‑methylstyrene (AMS) monomer using a turbidity-based spectrophotometric technique.

Q: What does it cover?

A: It covers sample preparation, measurement principle (turbidity after addition of dry methanol), applicable concentration range (validated up to ~15 mg/kg), the method's LOQ (~0.6 mg/kg) and LOD (~0.2 mg/kg), limitations (does not detect dimers/trimers), and relevant reporting/rounding practice (Practice E29).

Q: Who typically uses it?

A: QA/QC and analytical labs in chemical/petrochemical companies that make or use AMS, process control engineers, standards writers, and laboratories performing specification verification or interlaboratory comparisons.

Q: Is it current or superseded?

A: D7977‑23 is the current (2023) active edition and supersedes prior editions of D7977 (for example D7977‑19). ASTM lists D7977‑23 as active in the 2023 release.

Q: Is it part of a series?

A: Yes — it belongs to the family of ASTM standards covering styrenic and related aromatic hydrocarbons (Book of Standards volume 06.04) and is associated with specification and test-method standards such as D6367 and other D79xx series documents addressing monomer impurities and related analyses.

Q: What are the key keywords?

A: α‑methylstyrene, AMS, polymer content, turbidity, spectrophotometer, LOQ, LOD, ASTM D7977‑23.