This test method can be used for research or for quality control to characterize aromatic isocyanates and prepolymers of moderate to high acidity. Acidity correlates with performance in some polyurethane systems.

1.1 This test method determines the acidity, expressed as parts per million (ppm) of HCl, in aromatic isocyanate samples of greater than 100–ppm acidity. The test method is applicable to products derived from toluene diisocyanate and methylene-bis-(4–phenylisocyanate) (see Note 1).

Note 1—This test method is equivalent to ISO 14898, Test Method A.