Experimental multi-scale approach to determine the local mechanical properties of foam base material in polyisocyanurate metal panels

Polyisocyanurate (PIR) foams were examined regarding their local chemical composition using ATR-IR spectroscopy. As a special parameter the PIR: Amide III intensity ratio is to be mentioned, which represents the quantity of the formed PIR groups. Based on the local PIR: Amide III intensity ratio, the mechanical properties (Young's modulus) of the foam base material were analyzed at defined positions by AFM and Nanoindentation. It turned out that the AFM method is only suitable for qualitative analysis, because the values differ strongly from macroscopic measurements. For the measurements using nanoindentation, a new embedding method was developed, which achieves significantly more realistic and reproducible results compared to the embedding method used in the literature and shows a very good agreement with the macroscopic values. In general, it has been shown that a higher PIR: Amide III intensity ratio tends to lead to a higher Young's modulus. Nevertheless, there are other, currently unknown characteristic values which also influence the Young's modulus.

Automated summary

Polyisocyanurate (PIR) foams were examined for their local chemical composition using ATR-IR spectroscopy, with a focus on the PIR: Amide III intensity ratio as a parameter. Mechanical properties of the foam base material were analyzed at defined positions using AFM and Nanoindentation, with higher PIR: Amide III intensity ratio generally resulting in higher Young's modulus. The study also revealed the development of a new embedding method for nanoindentation, achieving more realistic and reproducible results compared to existing methods.