Quality control of polyols

Importance of the Topic

The hydroxyl value of polyols is a critical quality parameter in polyurethane and other polymer manufacturing. Fast, reliable determination of this parameter supports efficient process control, reduces waste, and ensures product consistency in both production and quality assurance laboratories.

Study Objectives and Overview

This work presents a ready-to-use near-infrared spectroscopy (NIRS) solution for measuring the hydroxyl value in polyols according to ASTM D6342-12 and ISO 15603:2011. It aims to streamline routine quality control by replacing traditional wet chemistry methods with rapid, non-destructive analysis.

Methodology

The approach relies on a DS2500 Near-Infrared Analyzer equipped with a pre-calibration model built from a large dataset of real polyol product spectra. No chemical reagents or sample pretreatment are needed. Measurements are completed in under one minute, with minimal operator training.

Instrumentation

• DS2500 Near-Infrared Analyzer
• 8 mm disposable vial sample holder
• Vision Air software for instrument control, data acquisition, and pass/fail evaluation

Main Results and Discussion

The pre-calibration model demonstrates excellent performance:

• Hydroxyl value range: 16–1180 mg KOH/g
• Standard error of cross-validation (SECV): 13.9 mg KOH/g
• Coefficient of determination (R²): 0.994

These metrics indicate high accuracy and reproducibility from the first use, enabling at-line QA/QC without additional method development.

Benefits and Practical Applications

• Rapid analysis (<30 s) reduces turnaround time by over 15 min per sample compared to wet chemistry.
• Chemical-free, non-destructive testing decreases cost and environmental impact.
• Simple operation allows non-specialists to perform routine checks, with advanced users able to manage SOPs and detailed data review.

Future Trends and Opportunities

Expanding the pre-calibration library with customer-specific samples can extend the method to additional parameters such as acid value and moisture. Integration with plant data systems may enable real-time process adjustments and predictive quality control.

Conclusion

This turnkey NIRS solution delivers fast, accurate hydroxyl value determination, supporting efficient polyol production and QA/QC workflows. Its user-friendly design and robust calibration model make it suitable for diverse industrial settings, offering significant time and cost savings over conventional methods.