Electromagnetic interference shielding effectiveness,electrical resistivity and mechanical performance of carbonized medium density fiberboard

The effect of carbonization temperature on the electromagnetic interference shielding effectiveness, electrical resistivity, and mechanical performance of medium density fiberboards carbonized in a vacuum furnace under a gas flow of nitrogen (200 mL/min) between 400℃ and 1500℃ was investigated. The medium density fiberboards specimens carbonized below 700℃ showed stable and low electromagnetic interference values (1.3–7.6 dB) between 10 MHz and 1 GHz frequency. The electromagnetic interference (average 43.1 dB) of the MDF specimens carbonized at 800℃ were suitable for industrial applications. However, the MDF specimens carbonized above 900–1500℃ showed high electromagnetic interference values (66.8–84.6 dB). When the carbonization temperature increased from 600℃ to 700℃, the electrical resistivity of the specimens greatly decreased (180.9 × 10³ to 137.5 Ω-cm). A further increment in the carbonization temperature (1200℃) had a small effect on the electrical resistivity (5.8 Ω-cm) of the specimens and no effect between 1300℃ (0.5 Ω-cm) and 1500℃ (0.5 Ω-cm). The carbonized specimens showed lower modulus of rupture and internal bond strength values than the untreated specimens but the differences between the strength values of the untreated specimens and the carbonized specimens decreased with increasing carbonization temperature. The modulus of elasticities of the specimens carbonized above 800℃ were higher than the untreated specimens.