Tall oil based rigid polyurethane foams thermal insulation filled with nanofibrillated cellulose

Two types of biopolyols based on tall oil were used for the preparation of rigid polyurethane (PUR) foams. High functionality biopolyol was synthesized from tall oil fatty acids by epoxidation and subsequent oxirane ring-opening with trimethylolpropane and tall oil esterification with triethanolamine was carried out to obtain low viscosity biopolyol. The optimal dispergation method with sonication was applied to obtain rigid PUR foams with 0-1.5 wt % of nanofibrillated cellulose. The influence of nanofibrillated cellulose content on the rigid PUR foams' closed-cell content, density, thermal conductivity, compression strength, and compression modulus was evaluated. Addition of NFC fiber into rigid PUR foam structure slightly increased compression strength and Young's modulus.