What Is FTIR Failure Analysis? Fourier Transform Infrared (FTIR) spectroscopy identifies materials and contaminants by measuring how a sample absorbs infrared light at different frequencies, producing a spectral “fingerprint” that’s compared against reference libraries. In failure analysis, FTIR is most often used to trace the root cause of field returns, warranty claims, or batch rejections back to a specific material or contamination source. Test Procedure Isolate the region of interest — a contaminant, discolouration, inclusion, or suspect surface Collect a spectrum via transmission, reflectance, or attenuated total reflectance (ATR) sampling, depending on sample form Compare the resulting spectrum against reference libraries to identify chemical class or specific compound For internal contamination in a known polymer matrix, apply spectral subtraction — computationally removing the base polymer’s peaks to isolate the contaminant signal Correlate findings with the failure mode under investigation to determine relevance (not every detected difference is causally linked to the failure) Applications in Failure Analysis Identifying foreign material or “black specks” in molded parts — thermally degraded polymer, carbonised screw/barrel residue, cross-contamination, or external particulates all look alike visually but differ chemically Detecting polymer degradation from heat, UV, or oxidative exposure via new functional groups in the spectrum Identifying chemical agents in contact with a failed part, distinguishing contamination from inherent material composition Confirming polymer identity for material substitution or counterfeit investigations Detection Limits and Interpretation FTIR can reliably detect contaminants down to roughly 100 ppm in favourable matrices, but a detected spectral difference doesn’t automatically mean it caused the failure — distinguishing a causally relevant contaminant from incidental variation is the harder, more experience-dependent part of the analysis. Industry Specifications Referencing FTIR ASTM E168, E1252: general practices for infrared quantitative and qualitative analysis Common companion techniques: XPS for surface-only contamination, SEM/EDS for morphology and elemental mapping Conclusion FTIR is often the fastest, lowest-cost first step in a failure investigation because it narrows down the chemical identity of an unknown quickly — but it works best as part of a broader analytical workflow, not as a standalone verdict on root cause.
