Real-time monitoring of polyurethane production using near-infrared spectroscopy.

A process near-infrared (NIR) spectrophotometer was interfaced directly to a reactor by using a fiber optic bundle interactance immersion probe. This remote sensor configuration enables the production of polyurethanes to be monitored in real-time. A Beer's Law model was derived for the quantitative determination of isocyanate in the urethane polymerization reaction. Statistical process control was used to observe trends in the polymerization reaction. The integration of NIR process analytical instrumentation directly into the process provides real-time chemical information that yields improvements in product quality and consistency, while minimizing reaction time.