Low-melting-point alloy integration into puffed wood for improving mechanical and thermal properties of wood–metal functional composites

To improve the mechanical and thermal properties of wood, a new functional composite was developed using an environmentally friendly low-melting-point alloy (LMA). Wood–metal functional composites (WMCs) were prepared by impregnating a puffed wood substrate with a LMA to form a LMA/wood network. The puffed wood was obtained by subjecting it to high-intensity microwave pretreatment. In-depth scanning electron microscopy coupled with energy-dispersive X-ray analysis showed the distribution of the LMA within the tracheid cells. The physical, mechanical, and thermal properties of the WMC were investigated. The weight percent gain (WPG), density, compressive strength parallel to grain (CS), thermal conductivity, and temperature unevenness of the WMC were found to increase with increasing crack number density in the puffed wood. The modulus of rupture (MOR) and the temperature alteration ratio were decreased for composites with an increased crack number density in the puffed wood. The WPG, density, CS, MOR, and thermal conductivity were increased by 1021%, 986.4%, 120%, 278.8%, and 2750%, respectively, from the unmodified wood to the optimal WMC. Such modified puffed wood with overall enhanced physical, mechanical, and thermal properties could be potentially utilized in applications like construction and heat-conductive flooring.