Thermal degradation of highly crosslinked rigid PU-PIR foams based on high functionality tall oil polyol

This study presents the development and analysis of rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesized from high functionality tall oil (TO) based polyols. Three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to a formulation developed using conventional raw materials, mainly obtained from petrochemicals. Using the Fourier transform infrared spectral analysis (FTIR), the chemical structure of the foams was evaluated with emphasis on the characteristic PU-PIR signal ratio and isocyanurate signal peaks. The thermal properties of the PU-PIR polymer matrix were characterized using the thermogravimetric analysis (TGA) method by comparing the thermal degradation temperatures at 5%, 25% and 50% and residual masses. Technological parameters and thermal degradation results indicate that TO is a suitable renewable resource for polyol in a rigid PU-PIR foam formulation, but the results from FTIR analysis suggest that a small optimization in the foam developing process is necessary due to an increasing amount of unreacted NCO groups in samples with the NCO index above 200. (C) 2019 Elsevier Ltd. All rights reserved.