Abstract:

Hydrophobic wood flour-silica aerogel composites were prepared by sol-gel method and ambient pressure drying with tetraethyl orthosilicate (TEOS) and methyltrimethoxysilane (MTMS) as co-precursors. The effects of different particle sizes (0.42-0.84 mm, 0.25-0.42 mm, 0.18-0.25 mm) of balsa woodflour on the properties of wood flour-silica aerogel composites were studied. Through the analysis of thermal conductivity, contact angle, infrared spectrum, thermogravimetric and compressive strength of composite materials, it was observed that the density, thermal conductivity, compressive strength and contact angle of the composites decreased with the increase of particle size of the wood flour. Wood flour with the particle size of 0.25-0.42 mm could endow aerogel composite with better material properties. Namely, the composite density was 0.168 g/cm³, the thermal conductivity was 0.033 7 W/(m·K), the compressive strength was 0.15 MPa, and the contact angle was 155.72°. The prepared composite material has the characteristics of excellent heat preservation performance, light weight and high hydrophobicity.

Key words: wood flour, silica aerogel, insulation materials, ambient pressure drying, light hydrophobic