Investigation on the flame-retardant and physical properties of the modified cellulosic and polyurethane aerogel

Abstract

Cellulose aerogel is of great interest for its origin of renewable biomass, so our target is the production of cellulose with flame-retardant and environmental-friendly. In this study, we synthesize cellulose aerogel from wastepaper and then, cellulose aerogel is modified with sodium bicarbonate to reduce the inflammability and the burning velocity. However, the mechanical properties of the obtained materials are not strong as the porous structure is easily broken. Therefore, the mixing cellulose aerogel with polyurethane (PU) has been synthesized to improve physicomechanical properties of aerogel. The porous structure of the aerogel is characterized by scanning electron microscope (SEM) analysis. The results show that the pore diameter of the sample is about 20–80 μm and the fiber size is in the range of 5–20 μm. The density and porosity are determined by changing the concentration of Sodium Hydroxide. The density results are of about 0.01–0.09 g/cm3, the porosity is about 94% ∼ –98% and the water absorption equals 20 times its weight. Adding NaHCO3 to cellulose aerogel will reduce its combustion and yield the firing velocity of the material after denaturation (0.25 mm/s) compared to the original material (3.45 mm/s) using UL 94 standards test. Finally, the compression stress of the PU/cellulose aerogel is subjected to 12 N/mm2 and offered a state of “returning” to their original height. Overall, PU-coated cellulose aerogel is a promising material that can be applied in many different fields with simple synthesis processes, inexpensive chemicals, and environmental-friendly materials.