ASTM D6437-22 PDF

Full title and description

Standard Test Method for Polyurethane Raw Materials: Alkalinity in Low-Alkalinity Polyols (Determination of CPR Values of Polyols). This concise ASTM test method specifies a potentiometric/autotitration procedure to measure very low levels of basic substances in polyether polyols, expressed as CPR (controlled polymerization rate) or as equivalent KOH basicity, for quality control, specification testing and research of polyurethane raw materials.

Abstract

ASTM D6437-22 defines a sensitive titrimetric procedure for determining alkalinity in low-alkalinity polyols (typically <0.002 meq/g basicity). The method uses an automatic/potentiometric titration approach to detect trace basic species (down to ppm KOH equivalents) that can affect urethane reactions with isocyanates. The test is intended for polyether polyols and is not applicable to amine-based polyols. Results are reported as CPR values or as milliequivalents of base per gram.

General information

• Status: Active standard
• Publication date: March 15, 2022
• Publisher: ASTM International
• ICS / categories: 83.040.01 — Raw materials for rubber and plastics in general
• Edition / version: D6437-22 (current edition)
• Number of pages: 3

Scope

This test method covers measurement of alkalinity in low-alkalinity polyols (commonly defined as less than 0.002 meq/g basicity). The alkalinity is usually expressed as CPR (controlled polymerization rate) for polyether polyols. The method is designed for very low levels of basic substances (detectable at ppm levels as KOH equivalents). It is not applicable to amine-based polyols. The standard gives required apparatus, reagents, titration procedure (potentiometric/autotitration), calculation and reporting conventions.

Key topics and requirements

• Purpose: detection and quantification of trace basic species in polyether polyols that can affect urethane chemistry.
• Applicability: low-alkalinity polyols (<0.002 meq/g); not for amine-based polyols.
• Analytical technique: potentiometric/automatic titration (autotitrator) with defined endpoint detection.
• Reporting: CPR values and equivalent basicity expressed as meq/g or ppm KOH equivalents.
• Equipment: potentiometric titrator/autotitrator, dosing buret, appropriate electrodes and calibration materials.
• Performance: capable of detecting ppm-level basicity; requires correct sample handling and reagent purity to avoid contamination.
• Safety and QA: users must follow laboratory safety practices and applicable regulatory limitations; method suitable for QC, specification testing and R&D.

Typical use and users

Primary users are polyol manufacturers, polyurethane formulators, quality control and analytical laboratories, and R&D teams working with polyether polyols and polyurethane prepolymers. Typical uses include incoming raw-material inspection, production process control, troubleshooting of polymerization or prepolymer reactions sensitive to base contamination, and specification compliance testing.

Related standards

Relevant ASTM and industry test methods and specifications often used alongside D6437-22 include: ASTM D7253 (Determination of Acidity as Acid Number for Polyether Polyols), methods for water content and viscosity of polyols (for example methods such as D4672 and D445 where appropriate), and other D20 committee documents covering polyurethane raw materials and isocyanate testing. There is no direct ISO equivalent specified in the standard.

Keywords

alkalinity, basicity, CPR, polyether polyol, polyol, polyurethane, prepolymer, titration, potentiometric titration, autotitrator, KOH equivalents, quality control

FAQ

Q: What is this standard?

A: ASTM D6437-22 is a standardized test method for measuring alkalinity in low-alkalinity polyols, providing a potentiometric/autotitration procedure to determine CPR values or equivalent basicity levels.

Q: What does it cover?

A: It covers the measurement of very low levels of basic substances in polyether polyols (typically <0.002 meq/g), the required equipment (automatic/potentiometric titration systems), procedure, calculation, and reporting of CPR or KOH-equivalent basicity. It excludes amine-based polyols.

Q: Who typically uses it?

A: Polyol manufacturers, polyurethane formulators, QC and analytical labs, and R&D groups use this method to ensure raw material quality and to troubleshoot or control reactions sensitive to trace basic contaminants.

Q: Is it current or superseded?

A: The current edition is D6437-22, approved and published in 2022. It is the active version of the standard as of the stated publication date.

Q: Is it part of a series?

A: D6437-22 is part of ASTM Committee D20 activity on plastics and polyurethane raw material test methods. It is commonly used alongside other D20 documents addressing acidity, water content and other properties of polyols (for example ASTM D7253).

Q: What are the key keywords?

A: Key keywords include alkalinity, basicity, CPR, polyether polyol, polyol, titration, potentiometric, KOH equivalents, polyurethane, prepolymer, quality control.