The Effect of Isosorbide Content on the Thermal and Compressive Properties of Closed-Cell Rigid Polyurethane Foam

In this study, isosorbide (ISB), a bio-based compound derived from the dehydration of D-sorbitol, was used as a sustainable resource to produce various types of rigid polyurethane foams (RPUFs). Featuring a rigid bicyclic structure and two hydroxyl groups, ISB was solubilized in polyether polyol at concentrations up to 10 wt% for RPUF production. ISB-based RPUFs exhibited smaller and more uniform cell sizes, along with a 4% increase in closed-cell content, resulting in improved thermal insulation with a 4.69% reduction in thermal conductivity. Additionally, the compressive strength increased by up to 31%, enhancing the material's durability. The compatibility of ISB with conventional raw materials and its unique structure contributed to these improvements. The reversible urethane bond formation of ISB was also observed, influencing cell structure during foaming. These results indicate that ISB can effectively improve both the thermal insulation properties and material durability under compression of RPUFs, making it a promising material for sustainable applications.