Polymer & Polyol Analysis

Importance of the topic

Near‐infrared spectroscopy (NIRS) offers a rapid, non‐destructive, and reagent-free approach to quality control in polymer and polyol production. It enables real‐time monitoring of critical parameters such as hydroxyl value, moisture, inhibitors, and isocyanate content, ensuring that raw materials, intermediates, and final products meet stringent industrial specifications while minimizing environmental impact.

Objectives and study overview

This summary reports on an interview with Guo Yuanfeng, technical engineer at Wanhua Chemical Group’s Yantai QC center. The discussion covers the adoption of the Metrohm NIRS XDS RapidLiquid (now DS2500 Liquid) Analyzer, method implementation, performance verification, and comparative advantages over traditional wet‐chemical techniques.

Used methodology and instrumentation

Methods involved development and validation of calibration models for multiple analytes in polymer and polyol matrices. Key steps included:

• Collecting a wide variety of sample compositions to build robust chemometric models.
• Comparing NIRS predictions against established primary methods for ongoing validation.

The principal instrument is the Metrohm DS2500 Liquid Analyzer (formerly XDS RapidLiquid Analyzer) configured with DS2500 Polymer and Polyol Analyzer pre-calibrations. Samples are measured in 8 mm disposable vials without any preparation. Data acquisition and model management are performed using Vision Air 2.0 software.

Main results and discussion

NIRS application demonstrated:

• Analysis times below one minute for multiple parameters simultaneously.
• High reproducibility and low maintenance requirements, enabling routine use by non‐specialist operators.
• Green credentials by eliminating toxic reagents and chemical waste.
• Limitations in trace‐level detection, necessitating complementary primary methods for very low‐concentration analytes.

Benefits and practical applications

• Fast, multiplexed quantification of hydroxyl value, moisture, polymerization inhibitors (TBHP, TBC), NCO content, mixed acids, color index, and viscosity.
• Reduced analysis costs and instrument downtime compared to wet chemistry.
• Enhanced QC throughput for incoming raw materials, intermediates, and final products across petrochemical and polyurethane production.

Future trends and potential applications

• Expansion of calibration libraries to cover minor constituents and complex copolymer systems.
• Integration of NIRS into online process control for continuous production monitoring.
• Advances in chemometric algorithms to improve sensitivity for low‐level analytes.
• Hybrid analytical platforms combining NIRS with complementary spectroscopic techniques (Raman, mid‐IR) for comprehensive material characterization.

Conclusion

Metrohm’s DS2500 Liquid Analyzer provides an efficient, sustainable alternative to traditional wet‐chemical methods for polymer and polyol analysis. When supported by rigorous calibration and validation workflows, NIRS enables high‐throughput, multiparameter quality control in diverse industrial settings.

Reference

No literature references were provided in the original text.