Electromagnetic wave absorption characteristics, electrical resistivity and micro pore structure of woodceramics prepared by powder method

Electromagnetic wave absorption characteristics, electrical resistivity and micro pore structure (specific surface area and micro pore size distribution) of the powder-method woodceramics, which were prepared by carbonizing the compacted mixtures of wood powder and 10- 30mass% of phenolic resin powder, were examined in comparison with those of the conventional MDF-method woodceramics, which were prepared by carbonizing the medium density fiber (MDF) boards impregnated with phenolic resin solution. The powder-method woodceramics carbonized at 650°C showed remarkable electromagnetic absorption characteristics as same as MDF-method woodceramics, namely the absorption values of 10%, 20% and 30% phenolic resin specimens were 35 dB at 11 GHz, 40 dB at 9 GHz and 50 dB at 2 GHz, respectively. These remarkable absorptions were mainly due to the suitably high electrical resistivities (10¹-10 ³Ωcm) of these woodceramics. The specific surface area of these woodceramics became to the maximum in the case of the carbonization at 700°C, namely 380m2·g^-1 in the 30% phenolic resin powder specimen, 300m²·g^-1 in the MDF specimen and 230m² · g^-1 in the 10% phenolic resin powder specimen, respectively.