Chemical gradients in PIR foams as probed by ATR-FTIR analysis and consequences on fire resistance

Taking into account numerous results from the literature, an in-depth exploratory study on chemical gradients in rise (or depth) direction was performed polyisocyanurate rigid (PIR) foam insulation panels using ATR-FTIR spectroscopy. In particular, it found that isocyanurate/phenyl ratio is a quick and effective technique for providing indication of level trimer conversion within each sample. More importantly, detailed analysis C–N stretching vibration isocyanurate ring as function depth revealed linear decrease frequency peak maximum with increase all investigated PIR foams. This result suggests first time position (frequency) (C–N ring) may be used to quantify extent formation without issues linked use absorbances. It proposed this reduction reflects hydrogen bonding between N–H urethane group CO when content increases (lower mobility associated higher cross-linking). The heterogeneity physically confirmed by investigating flammability samples taken at different positions (z-axis).