Preparation and properties of waterborne polyurethane/nanocellulose/sepiolite composite aerogel for sound absorption and heat insulation.

Faced with all kinds of serious ecological and environmental protection problems in today's society, development must take the sustainable and green road. Nanocellulose aerogels with the advantages of wide resource of raw materials, low cost, good biocompatibility and biodegradation, are good thermal and sound insulation materials. Herein, a versatile composite aerogel with good thermal stability and heat-insulating property was prepared by freeze-drying method using cellulose nanocrystals (CNCs), waterborne polyurethane (WPU) and sepiolite (SEP) as substrates. The initial degradation temperature is above 200 °C, the temperature difference is >35 °C after 30 min at 80 °C, and the thermal conductivity is between 0.03 and 0.05. Additionally, it has good compression performance and sound absorption performance, and the maximum compressive stress is slightly reduced from 0.0245 MPa to 0.0231 MPa after 10 cycles of compression at 40 % maximum strain. The average sound absorption coefficient of aerogel in band of 100-6000 is >0.7.