To Fourier Transform Infrared Spectrometers Coupling Thermal Analyzer

Significance of Topic

Coupling thermal analysis with Fourier transform infrared spectroscopy closes the gap between mass or heat flow measurements and the identification of gaseous products. This combined approach yields both quantitative data on transitions and decomposition and fingerprint spectra of evolved species, aiding research, quality control and materials development.

Study Aims and Overview

The article presents integrated concepts for hyphenating NETZSCH thermobalances and simultaneous thermal analyzers with Bruker FT-IR systems. It outlines harmonized instrument configurations, software integration, and demonstrates the benefits through representative case studies including polymers, pharmaceuticals, fertilizers and building materials.

Methodology and Instrumentation

In the coupling design, a heated transfer line connects the furnace outlet to a gas cell located inside or external to the spectrometer. Heating prevents condensation and preserves sample integrity. Key components include:

• NETZSCH instruments: TG 209 F1 Libra, TG 209 F3, STA 2500 Regulus, STA 449 series, DSC 204 Phoenix
• Bruker FT-IR platforms: INVENIO, VERTEX, ALPHA II and the compact PERSEUS interface
• Gas cells with long path length and low volume, KBr or ZnSe windows
• Detectors: room temperature DLaTGS and liquid nitrogen cooled MCT for enhanced sensitivity
• Software: Proteus controls thermal analysis, OPUS handles IR acquisition; data exchange maintains precise time and temperature correlation

Main Results and Discussion

Several examples illustrate the power of TG‐FT‐IR coupling:

• Ethylene vinyl acetate decomposes in two steps in nitrogen; acetic acid is released at ≈350 °C followed by polymer backbone collapse at ≈468 °C, as confirmed by FT‐IR band assignments.
• Aspirin tablets undergo dehydration and hydrolysis; FT‐IR detects acetic acid, salicylic acid, phenol and CO2 concurrent with DSC peaks for melting and decomposition.
• Urea shows three decomposition stages: NH3 and HNCO evolve around 180 – 200 °C, cyclization to cyanuric acid above 200 °C, and full release of cyanuric acid near 310 °C.
• Clay firing for porous bricks reveals organic burnout between 200 °C and 550 °C, releasing H2O, CO2, HF and SO2. The combination of mass loss, heat flow and IR spectra allows optimization of firing protocols.
• Silicone synthesis quality control identifies cyclooctamethyltetrasiloxane intermediates in one sample, indicating incomplete polymerization.

Benefits and Practical Applications

This hyphenated approach offers:

• Simultaneous measurement of mass, heat flow and gas composition with maintained temperature‐time alignment
• Fingerprint identification of volatile compounds for material characterization and failure analysis
• High sensitivity and reduced sample throughput time with optional automatic sample changers
• Versatile applications in polymer processing, pharmaceutical stability, catalyst testing, combustion and evaporation studies

Future Trends and Potential Uses

Advancements may include expanded spectral libraries for rapid identification, deeper integration with mass spectrometry or gas chromatography, higher‐sensitivity detectors, real‐time remote diagnostics, and automated workflows for high‐throughput screening in industrial and research laboratories.

Conclusion

FT‐IR coupling significantly enhances the capabilities of thermal analysis by delivering rich qualitative and quantitative insights into evolved gases. Harmonized hardware and software solutions ensure straightforward operation, reproducibility and broad applicability across diverse analytical challenges.