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

Abstract

Rigid polyurethane foams were successfully prepared by blending up to 70wt% of two different palm oil-based bio-polyolswith a petrochemical polyether polyol. The bio-polyols were synthesized by epoxidation?oxirane ring-opening process usingwater (PP102) and diethylene glycol (PP147), respectively. Due to the high viscosity of both bio-polyols the reactive mixturewas heated to start the foaming reaction at about 50 ∘C. Under these conditions, the gelling reactions speed up as the amountofPP147increases but slowdownto agreat extentwhenPP102is used. The thermal conductivityofmodified foamsishigher andthe closed cell content lower compared to reference ones, evenwhen 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 to400 ∘C than the control foam. Conversely, their mechanical and dynamic mechanical properties become poorer as the PP147concentration increases and even more so if PP102 is used instead. PP147 foams containing up to 50% bio-polyol could beused as a green replacement of petroleum-based ones in applications where excellent behaviour in compression (the mostaffectedproperties) is not fundamental,with the additional advantages of reduced density and increased content ofbio-derivedcomponents.