Humidity dependence of impedance for woodceramics made from waste paper

Waste paper of postcards was used for the fabrication of woodceramics (WCMs). The electrical impedance and humidity sensitivity were measured. The impedance for WCMs fabricated from the waste paper (WP-WCMs) decreased with the increase of annealing time at 620 degrees C and the impedance of WCMs mixed with 40% phenolic resin was smaller than that of WCMs mixed with 30% phenolic resin. The WP-WCMs had higher quality than WCMs fabricated from medium density fiberboard (MDF-WCMs). In addition, the humidity sensitivity was twice as large as that of MDF-WCMs, because the density of WP-WCMs was smaller than that of MDF-WCMs and the specific surface area of WP-WCMs was larger than that of MDF-WCMs. Consequently, waste paper of postcards is suitable raw material for WCMs humidity sensor.