Synthesis and properties of polyurethane foams prepared from heavy oil modified by polyols with 4,4′-methylene-diphenylene isocyanate (MDI)

► Polyurethane foams could not be directly prepared from heavy oil for its low hydroxyl number. ► After modification, heavy oil increased its hydroxyl number to 564.5mgKOH/g. ► Furthermore, the secondary alcohol hydroxyl was the main product. ► The compressive strength of foams increased 32% by adding 10% activated heavy oil. ► However, adding 100% activated heavy oil would weaken the properties of PU foams. The aim of the present study was to determine whether polyurethane (PU) foams can be prepared from heavy oil derived from biomass liquefaction. Since the hydroxyl number of the heavy oil was only 212mgKOH/g, it was modified by polyols, and a hydroxyl number of 564.5mgKOH/g was obtained. However, secondary hydroxyls rather than primary hydroxyls were introduced. As a result, when 10wt.% activated heavy oil was added to bio-polyols, compressive strength of foams increased by 32% over that without the addition of heavy oil. When activated heavy oil wholly replaced polyethylene glycol 400, the high content of secondary hydroxyls depressed the foam reaction and resulted in partial dissociation of the heavy oil from the network structure and weakening of the thermal stability of the PU foams. Therefore, increasing the content of primary-hydroxyls by directional modification is necessary to make the process commercially feasible.