The effect of different palm oil-based bio-polyols on foaming process and selected properties of porous polyurethanes

Rigid polyurethane foams were successfully prepared by blending up to 70 wt% of two different palm oil-based bio-polyols with a petrochemical polyether polyol. The bio-polyols were synthesized by epoxidation-oxirane ring-opening process using water (PP102) and diethylene glycol (PP147), respectively. Due to the high viscosity of both bio-polyols the reactive mixture was heated to start the foaming reaction at about 50 degrees C. Under these conditions, the gelling reactions speed up as the amount of PP147 increases but slow down to a great extent when PP102 is used. The thermal conductivity of modified foams is higher and the closed cell content lower compared to reference ones, even when the bio-foams present a lower apparent density. However, all foams exhibit reduced water absorption, excellent dimensional stability and better thermal stability at temperatures up to 400 degrees C than the control foam. Conversely, their mechanical and dynamic mechanical properties become poorer as the PP147 concentration increases and even more so if PP102 is used instead. PP147 foams containing up to 50% bio-polyol could be used as a green replacement of petroleum-based ones in applications where excellent behaviour in compression (the most affected properties) is not fundamental, with the additional advantages of reduced density and increased content of bio-derived components. (C) 2017 Society of Chemical Industry