ASTM D5523 - 10

    Standard Test Method for Polyurethane Raw Materials Acidity by Argentometric Determination of Hydrolyzable Chlorine in Monomeric, Aromatic Isocyanates

    Active Standard ASTM D5523 | Developed by Subcommittee: D20.22

    Book of Standards Volume: 08.03


    Buy Standard (PDF)
    3 pages
    $37.00
    Buy Standard (Print)
    3 pages
    $37.00
    Buy Standard + Redline (PDF)
    6 pages
    $44.40

    Historical (view previous versions of standard)


    ASTM D5523

    Significance and Use

    This test method is suitable for research or for quality control to characterize TDI and MDI.

    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.

    1. 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 and health practices and determine the applicability of regulatory limitations prior to use.

    Note 1—There is no known ISO equivalent to this standard.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D883 Terminology Relating to Plastics


    ICS Code

    ICS Number Code 83.080.20 (Thermoplastic materials)

    UNSPSC Code

    UNSPSC Code 12352100(Organic derivatives and substituted compounds)


    DOI: 10.1520/D5523-10

    ASTM International is a member of CrossRef.

    ASTM D5523

    Citing ASTM Standards
    Back to Top