Optimizing Water‐Blown Lignin‐Based Rigid Polyurethane Foam: Formulation Strategies for Enhanced Mechanical and Thermal Performance

ABSTRACT Rigid polyurethane foam (RPUF) holds a prominent position in thermal insulation materials. The mechanical and thermal properties of these materials are closely associated with their cell size, structure, and shape. Therefore, optimizing the formulation and ratio is essential. In response to the global demand for sustainable development and the need to reduce reliance on carbon‐intensive, nonrenewable resources, water‐blown RPUF was synthesized using lignin‐based polyols (LP). The effect of formulation additives on the properties of lignin‐based rigid polyurethane foam (LRPUF) was systematically investigated. The formulation of high‐performance all water‐blown LRPUF was optimized. Under the optimized formulation, the reaction time of LRPUF was approximately 153 s. LRPUF of 0.069 g/cm 3 exhibited a compressive strength of 481.91 kPa and thermal conductivity of 0.039 W/mK. The cell size of LRPUF ranged from about 0.2 to 1 mm and exhibited a relatively smooth texture. Compared to petroleum‐based RPUF, LRPUF demonstrated superior thermal stability, with a carbon residue rate of 28% at 800°C.