Polyurethane rigid foams obtained from polyols containing bio-based and recycled components and functional additives

We report the preparation of polyurethane (PU) rigid foams from bio-based and recycled components. Rapeseed oil (RO) and recycled polyethylene terephthalate (rPET) were used to synthesize PU polyols. Fifty-five percent of the content of the proposed PU polyols originates from renewable or recycled material. Glycerol (GL) and adipic acid (ADA) were added to improve the final properties of the foams. The GL/ADA content was varied from 1 to 6 wt.%. The hydroxyl value, acid value, water content, and viscosity of the synthesized polyols were measured. Using compression tests on PU rigid foams, we found that for some GL/ADA contents the rigidity increased almost 3-fold; whereas the strength increased almost 2-fold. The water absorption of the foams was below 3 wt.%. Optical microscopy of foam cross-sections revealed a mean cell sizes of 330 μm for PU with GL/ADA, and 420 μm for PU supplemented with GL/ADA and RO. FTIR measurements revealed enhanced hydrogen bond networking due to the incorporation of GL/ADA fragments and RO long aliphatic blocks in the PU chain backbone.