FTIR Analysis of Glues for Quality Control and Development

Importance of the Topic

Adhesives are vital in sectors ranging from automotive assembly to medical applications. Ensuring their chemical identity and performance properties is critical for product reliability and safety. FTIR spectroscopy provides a fast, non-destructive approach to characterize both raw materials and finished adhesive formulations.

Objectives and Study Overview

This application note demonstrates the use of FTIR techniques for quality control, product development, and failure analysis of adhesives. Key aims include incoming goods inspection, reaction monitoring of curing processes, reverse engineering of unknown formulations, and spatially resolved defect analysis.

Methodology and Instrumentation

Attenuated total reflection FTIR enables rapid spectrum acquisition without sample preparation. Time-resolved measurements track changes during curing. Mixture analysis algorithms identify components in complex samples. FTIR microscopy provides micrometer-scale mapping of compositions within adhesive layers.

Used Instrumentation

• LUMOS II FTIR microscope with ATR module and motorized polarizers
• ALPHA II FTIR spectrometer with interchangeable ATR unit
• OPUS software for quick compare, reaction monitoring, and mixture analysis

Main Results and Discussion

• Incoming goods inspection achieved over 99 percent correlation against reference spectra, confirming raw material identity.
• Reaction monitoring of a model plastic adhesive tracked solvent evaporation and polymer concentration via integration of characteristic bands (1040 cm-1 for butyl acetate, 1144 cm-1 for PMMA).
• Mixture analysis of an unknown multi-purpose glue revealed a water-based acrylate polymer formulation with only minor spectral deviations.
• Failure analysis using FTIR microscopy identified needle-shaped crystalline contaminants on PET foil, and spectral comparison excluded suspected amide impurities.

Benefits and Practical Applications

• Fast, reagent-free identity verification of raw materials and products
• Quantitative monitoring of curing kinetics to optimize production
• Reverse engineering supports competitive benchmarking and patent evaluations
• High-resolution defect mapping aids root cause investigations

Future Trends and Potential Applications

Advances may include integration of chemometric models for automated classification, real-time inline monitoring in production lines, combination with imaging modalities for multi-technique analysis, and miniaturized, portable FTIR devices for field applications.

Conclusion

FTIR spectroscopy and microscopy offer versatile solutions for adhesive quality control and development. The ease of sample handling, speed of analysis, and spatial resolution make these techniques indispensable for both routine inspections and advanced research.