Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE A novel solvent-free oxyalkylation approach enables efficient conversion of organosolv lignin into bio-based polyols using a glycidol/ethylene carbonate system. The resulting polyols exhibit appropriate physicochemical properties for rigid polyurethane foam production without requiring purification steps. The foams show good mechanical performance, enhanced thermal stability, and high biodegradability, supporting sustainable material development.


ABSTRACT
The development of bio-based polyols remains a key challenge in the production of environmentally friendly polyurethane materials. Lignin, although an abundant by-product of the pulp and paper industry, exhibits limited reactivity and typically requires modifications before it can be applied as a polyol component. In this work, organosolv lignin was successfully converted into functional polyols via oxyalkylation using a glycidol/ethylene carbonate reagent system, which has not previously been reported for lignin valorization. The resulting polyols exhibited hydroxyl numbers, viscosities, densities, and surface tensions appropriate for rigid polyurethane foam production, and did not require post-reaction neutralization steps typical of strong catalysts (e.g., NaOH or H2SO4), nor the removal of solvent or solid residues. Rigid polyurethane foams formulated from these polyols were comprehensively characterized. The foams displayed apparent densities of 58–96 kg m−3, compressive strengths of 0.201–0.449 MPa, and water uptake values of 4.0%–6.7%. Their thermal performance exceeded that of conventional petrochemical polyurethane foams, maintaining structural integrity after prolonged exposure to 150°C. Importantly, the materials demonstrated high susceptibility to biodegradation, reaching 63% degradation in soil after 28 days. The proposed method provides an efficient pathway for lignin valorization and yields sustainable, biodegradable polyurethane foams aligned with circular-economy and green-chemistry principles.