Standard Test Method for Polyurethane Raw Materials: Acidity by Argentometric Determination of Hydrolyzable Chlorine in Monomeric, Aromatic Isocyanates
Standard Test Method for Polyurethane Raw Materials: Acidity by Argentometric Determination of Hydrolyzable Chlorine in Monomeric, Aromatic Isocyanates
SIGNIFICANCE AND USE 5.1 This test method is suitable for research or for quality control to characterize TDI and MDI. 5.2 This test method was developed to overcome problems with low-level acidity determinations that use glass electrodes in the presence of reagent alcohol solvents. Reagent alcohols contain acidic and basic species, which complicate the glass electrode methods at low levels of acidity. SCOPE 1.1 This test method measures the hydrolyzable chlorine content of monomeric, aromatic isocyanates used as polyurethane raw materials and expresses it as HCl acidity. The test method is applicable to toluene diisocyanate (TDI) and monomeric methylene di(phenylisocyanate), known as MDI. The main sources of hydrolyzable chlorine and, therefore, acidity in monomeric aromatic isocyanates are carbamyl chlorides, acid chlorides, and dissolved phosgene. All of these compounds react with alcohols and water to form hydrochloric acid. 1.2 This test method applies only to monomeric isocyanates in which all of the acidity is derived from species that generate HCl on solvolysis. 1.3 The values stated in SI units are to be regarded as the 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. Note 1: There is no known ISO equivalent to this standard. 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.
ASTM D5523-21: Standard Test Method for Polyurethane Raw Materials: Acidity by Argentometric Determination of Hydrolyzable Chlorine in Monomeric, Aromatic Isocyanates is an essential standard developed by ASTM International. It provides a reliable test method for measuring the hydrolyzable chlorine content in monomeric, aromatic isocyanates-namely toluene diisocyanate (TDI) and methylene di(phenylisocyanate) (MDI). This acidity, expressed as hydrochloric acid (HCl), is critical for the characterization and quality control of polyurethane raw materials. The test addresses specific analytical challenges associated with low-level acidity determinations, particularly in the presence of reagent alcohol solvents.
Scope and Applicability
Testing Method
Precision and Bias
Safety and Handling
Quality Control and Certification
Другие стандарты ASTM
Research and Development
Manufacturing Assurance
Compliance and Reporting
ASTM D883 – Terminology Relating to Plastics
ASTM E456 – Terminology Relating to Quality and Statistics
ASTM E2935 – Practice for Conducting Equivalence Tests for Comparing Testing Processes
acidity, hydrolyzable chlorine, isocyanates, TDI, MDI, polyurethane, titration, argentometric determination, quality control, raw materials, ASTM D5523-21
ASTM D5523-21 sets the benchmark for accurately determining acidity by measuring hydrolyzable chlorine in aromatic isocyanates, thereby supporting the reliability, safety, and performance of polyurethane manufacturing and research worldwide.