Using FT-NIR Spectroscopy to Determine NCO% In Polyurethane Polymers

FT-NIR Spectroscopy executes a rapid and non-destructive resolution of NCO% in Polyurethanes.

Measurement Made Simple

Polyurethane polymers are implemented in the production of foams, inks, adhesives, synthetic fibers, and plastics.

Polyurethane polymers are typically, and most frequently, constituted following the reaction of a polyol with an isocyanate. Through measurement of the NCO%, it is possible to monitor the reaction's developments.

Polyurethane foam

Polyurethane foam

Polyurethane polymerization reaction

Polyurethane polymerization reaction

Application Details

FT-NIR is an appealing substitute because it permits the execution of a quick, non-destructive verification of NCO% in polyurethanes. Each sample can be examined in under a minute, and the trial can be undertaken by an operative without an analytical background.

The FT-NIR methodology will conventionally display a reproducibility not dissimilar to established laboratory techniques, but with far superior repeatability and robustness.

This study illustrates the implementation of an ABB FT-NIR instrument (PTPA2000-260) for rapid determination of NCO% in polyurethane polymer.


  • Instrument: FTPA2000-260
  • Detector: InGaAs, 2.6 µm TEC
  • Sampling technique: transflectance probe
  • Analysis temperature: 65 to 70 °C (149 to 158 °F)
  • Path length: 10 mm
  • Number of scans: 128
  • Resolution: 16 cm-1
  • Chemometrics model: Partial Least Squares (PLS)


Calibration NCO% plots: actual vs predicted

Calibration NCO% plots: actual vs predicted

Calibration Results

Property Range (%) R2 SECV (%)
NCO% 0 to 0.86 0.998 0.012


FTPA2000-260 analyzer

FTPA2000-260 analyzer


The research undertaken by ABB has demonstrated the feasibility of online monitoring of NCO% by NIR.

The experiment was performed utilizing a transflectance probe. However, for an industrial function, the use of a transmission probe or a flow through cell is recommended for greater repeatability and a more simple cleaning process.

This information has been sourced, reviewed and adapted from materials provided by ABB Measurement & Analytics - Analytical Measurement Products.

For more information on this source, please visit ABB Measurement & Analytics - Analytical Measurement Products.

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