High-yield bio-polyols from sugarcane bagasse: process optimization, structural analysis, and application potential

Abstract This research addresses the management of agricultural waste and the partial substitution of petrochemicals in polyurethanes (PUs) by utilizing renewable resources. The present study evaluates, both quantitatively and qualitatively, the feasibility of producing bio-polyols from sugarcane bagasse by polyethylene glycol (PEG 400) as organic solvent. These polyols can be potentially utilized as substitute for petrochemical polyols in elastic PU formulations. The effects of process conditions (temperature, catalyst content, and sugarcane bagasse: solvent ratio) on the bio-polyol yield were evaluated and optimized using response surface methodology through a Box-Behnken design. In addition, at each experimental point, the qualitative characteristics of the resulting bio-polyols, including functional groups, hydroxyl number ( I OH ), acid number ( A n ), molecular weight ( M W ), functionality, viscosity, and polydispersity index (PDI) were determined. The optimal conditions identified by the model determined the most effective experimental parameters as 2 g of sugarcane bagasse, 3.13% catalyst, and a reaction temperature of 161.1 °C. Under these conditions, a polyol yield of 95.6% was achieved, with a prediction error of 4.4%. For the high‑yield samples, I OH ranged from $$\sim$$ ∼ 195 to 233 mg KOH · g⁻ 1 , M W from 3839.27 to 7582.06 g · mol⁻ 1 , functionality between 3.12 and 4, viscosity from 187.5 to 238.4 mPa · s, and PDI between 4.25 and 7.50. These results indicate that the synthesized bio-polyols possess physicochemical characteristics comparable to those reported for polyols used in elastic polyurethane formulations, suggesting their potential suitability for such applications. Overall, the study presents innovative strategies for cost-effective laboratory-scale production of bio-polyols, offering a pathway toward broader industrial adoption.