Modified raw cellulose filaments material as polyol substitute in rigid insulating polyurethane foam

Current research in building insulation is primarily focused on enhancing the performance of polyurethane foam or exploring alternatives with biobased materials, with particular attention placed on polyols. This study investigated the use of modified cellulose filaments as a polyol to enhance the environmental performance of polyurethane foam. Two distinct etherification methods were employed to modify cellulose filaments (CFs), yielding accessible and reactive ether functions from the hydroxyl (OH) groups of CFs. Polyols and the resulting polyurethane foam were characterized. Kinetics of foam formation, morphology, density, thermal conductivity, and mechanical properties in compression were studied. Analysis revealed reduced reactivity with modified CFs as a substitute of the petroleum-based polyol, affecting foaming. Impacts on the resulting properties of the foam were observed, such as the size of the cells (from 0.14 ± 0.06 mm² for petroleum-based polyol foams to 0.03 ± 0.03 mm² for foams with 70% substitution with biobased polyols 1 and 2), and cells opening (from 92 ± 2% for petroleum-based polyol foams to 8 ± 3% with 70% substitution with biobased polyols). These results lead to non-compliance with the canadian polyurethane foam standard, requiring a closed cell rate of over 90%. A deterioration in mechanical properties through loss of stiffness and a drastic reduction in the maximum strength (yield strength) the material can withstand below the required standard were also measured. However, noteworthy conductivity results were obtained (0.041 ± 0.004 W m^-1‧K^-1 with 70% of substitution with biobased polyols 1 and 2). Foam properties were partly due to different polyol properties, such as functionality and viscosity.