Polyether polyols are polymers formed by the ring-opening polymerization of a polyol (e.g. propylene glycol) and epoxides (e.g. PO, EO). They are typically viscous liquids ranging from colorless to light yellow, known for their excellent low-temperature flexibility, hydrolytic stability, and good processability.

The solid content of polyether polyols refers to the mass percentage of non-volatile substances (i.e., actual effective ingredients) in polyether polyols. It is a crucial parameter that directly impacts product performance and production efficiency.

I. Importance of Solid Content

1. Polyether polyols with high solid content imply having a higher amount of effective ingredients per unit weight, reducing the solvent usage in the production process, enhancing production efficiency, and cutting costs.
2. Solid content influences the rate and extent of the reaction between polyether polyols and isocyanates, thereby affecting the product performance.

II. Methods for Solid Content Analysis

1. Gravimetric Method
Basic Principle: The gravimetric method involves drying to eliminate volatile components  (e.g. water and solvents) in the sample. The mass difference before and after drying is calculated to determine the solid content.
Application: This method is one of the most direct and commonly used approaches.

2. Karl Fischer Titration
Basic Principle: The Karl Fischer reagent reacts with moisture to produce iodine, which is then quantified via potentiometric titration to determine the moisture content in the sample, enabling indirect estimation of the solid content.
Application: Due to the low moisture content in polyether polyols, this method is suitable for precise analysis of high-solids samples.

3. Gas Chromatography
Basic Principle: Compare the peak areas in the sample solution with those in a standard solution, and then determine the solvent content, allowing for the indirect calculation of the solid content.
Application: Suitable for polyether polyols containing specific solvents.

4. Near-Infrared Spectroscopy
Near-infrared spectroscopy is a rapid and non-destructive analysis method. It’s applicable for online monitoring and quality control. By analyzing absorption bands in the near-infrared spectral region, this method utilizes calibration models to predict the solid content fo a sample. Near-infrared spectroscopy offers several advantages such as ease of operation, fast analysis, and good reproducibility.

III. Conclusion

The solid content is a key factor influencing performance and application of polyether polyols. An appropriate analysis method should be chosen for a specific polyether polyol. Accurate determination of solid content is crucial for optimizing production processes and enhancing product quality.