Eco-friendly polyurethane foams enriched with sodium hydroxide modified wastepaper filler

: In the presented study, rigid polyurethane foams were modified with a filler in the form of beech wood pulp modified with sodium hydroxide solution. The effects of 0.2, 0.2, 1.2, 2.3, 3.5 and 4.7 wt.% of the filler on the performance of the foams were investigated. The best thermo-mechanical properties were characterised by composites containing 3.5 wt.% of filler. The samples were characterised by increased damping capacity after thermo-oxidative ageing, lower water absorption (about 38%) and reduced thermal conductivity. The addition of a thermally unstable cellulose filler did not impair the thermal stability of the PU. The developed compositions confirm the possibility of using paper as a modifier for rigid polyurethane foams. The additive strengthens the composites, protects them from the effects of thermo-oxidative ageing and makes them suitable for use in higher humidity environments. • Rigid polyurethane (PU) foams were successfully modified with a filler in the form of beech wood pulp modified with sodium hydroxide solution. The effects of 0.2, 0.2, 1.2, 2.3, 3.5, and 4.7 wt.% of the filler on the performance of the foams were investigated. • The best thermo-mechanical properties were characterized by composites containing 3.5 wt.% of filler. • The use of filler in higher amounts by weight (i.e. above 5 wt.%), resulted in a collapse of the foam structure and a deterioration of the physical-mechanical properties.