The influence of crude glycerol and castor oil-based polyol on the structure and performance of rigid polyurethane-polyisocyanurate foams

• Crude glycerol-based polyol was used to produce rigid PU-PIR foams.
• Crude glycerol-based polyol enhance compressive performance of PU-PIR foams.
• Use of prepared biopolyol enhance thermal insulation properties of PU-PIR foams.
• Use of crude glycerol-based polyols change combustion pathway of PU-PIR foams.

In this work, biopolyol obtained from two types of industrial crops’ processing products: crude glycerol and castor oil was used for preparation or rigid polyurethane-polyisocyanurate foams. Bio-based polyol was obtained via crude glycerol polymerization and further condensation of resulting polyglycerol with castor oil. Rigid polyurethane-polyisocyanurate foams were prepared at partial substitution (0–70 wt.%) of petrochemical polyol with synthesized bio-based polyol. Influence of the biopolyol content on the chemical and cellular structure, insulation properties, static and dynamic mechanical properties, thermal degradation and fire behavior of foams was investigated. Incorporation of crude glycerol-based polyol into formulation of rigid polyurethane-polyisocyanurate foams had beneficial impact on the structure of material reducing average cell size from 372 to 275 μm and increasing closed cell content from 94.0 to 95.7%. Such changes resulted in 7% decrease of thermal conductivity coefficient to 21.8 mW/(m K). Mechanical performance of foams was enhanced by partial substitution of petrochemical polyol with synthesized biopolyol. Compressive strength of modified foam was more than 90% higher than for reference sample. The modifications of foams caused changes in thermal degradation pathway, nevertheless thermal stability of the reference foam was maintained. Incorporation of crude glycerol-based polyol into foams’ formulation decreased maximum value of heat release rate by 3.5%, increased char residue after combustion by 24% and reduced emission of toxic carbon monoxide during burning of foam by 35%.