Determination of isocyanate group content in polyurethane prepolymer

This document specifies two methods for determining the content of isocyanate groups (NCO) in polyurethane prepolymers or intermediates: Method A, di-n-butylamine-anhydrous toluene/hydrochloric acid standard titration solution method; Method B, near-infrared spectroscopy method. These methods are suitable for use by polyurethane prepolymer manufacturers or related parties to determine the isocyanate group (NCO) content in their products using the di-n-butylamine-anhydrous toluene/hydrochloric acid standard titration solution method and the near-infrared spectroscopy method. They can also be used by relevant units for research and quality control of such products.