Fourier Transform Infrared Spectroscopy (FTIR) is a chemically-specific analysis used to obtain an infrared spectrum of absorption/emission of a solid, liquid or gas. It can be used to identify chemical compounds and substituent groups. FTIR is an absorption technique where an infrared radiation interacts with a molecule. The term Fourier transform infrared spectroscopy originates from the fact that a Fourier transform (a mathematical process) is required to convert the raw data into the actual spectrum.
FTIR technique is very useful for coating failure analysis and is being employed in the following tests:
• Generic identification: powerful technique for the elucidation of molecular structure. Determining if a failing coating really is the specified epoxy.
• Detection of contaminants: coating applied over contamination is a common failure reason. Sometimes the contaminant is not apparent visually and spectroscopic method is required.
• Identification of mix-ratio problems: many high-performance thermoset coatings consist of two components that must be mixed together shortly before application.
• Detection of coating degradation evidence: coating might fail because of chemical degradation of environment, which may result in changes in chemical composition.
• Degree of cure monitoring: cure process of thermoset coatings involve breaking and forming of chemical bonds with characteristic absorption bands in the infrared.
Temperature: room temp.
Scan range: 400 to 4000 cm-1
Scan resolution: typically 2cm-1
• Powder coating or coating flakes
• Coated panels
• Thick liquid samples (slurry)
• ASTM E 1252
• ASTM E 168
Charter Coating’s FTIR setup (PerkinElmer Spectrum 100 FT-IR)