The optimization of thermal insulation-related properties of polysaccharide-based aerogel by the multi-layer combination method

The development of polysaccharide-based biodegradable thermal insulation aerogels benefited environmental protection. The thermal conductivity of polysaccharide-based aerogels prepared by the freeze-drying method was difficult to reduce to less than 0.3 W/(m·k), as the pore size was relatively large. Therefore, rather than reducing pore size, this study aimed to reduce the airflow/heat convection inside the aerogels by introducing aerogels with different air permeability as outer layers to combine dual-layer/triple-layer aerogels with lower thermal conductivity. Results showed that the triple-layer method had a more significant impact on reducing the thermal conductivity than the dual-layer method, due to the greater impact on reducing the airflow. Additionally, a thinner thickness of outer aerogel layers was preferred, and the thermal conductivity was significantly reduced to 0.0279 W/(m·k) from 0.0335 W/(m·k) by the triple-layer aerogel method. The thermal insulation stability of this triple-layer aerogel was also relatively high, and the hardness and resistance to relative humidity were both improved compared to the original aerogel. Considering the above, this triple-layer aerogel method could be used to improve the thermal insulation-related property of the polysaccharide-based aerogels by the freeze-drying method or with relatively large pore sizes.