Study On Properties Of Carbon-based Electromagnetic Shielding Fiberboard

Radiations from different devices cause serious electromagnetic interference which will significantly influence the performance realization of other electromagnetic devices and result in information compromising emanations. And it even could result in serious health hazards to human beings. The carbon fiber(CF) with different lengths and filling amounts was mixed with wood fiber by solution blend method to prepare carbon-based electromagnetic shielding fiberboard with high conductivity, stable shielding performance and physical and mechanical properties. Microstructure, conductivity, shielding effectiveness(SE), physical and mechanical properties of fiberboards filled in CF with different lengths and filling amounts were investigated. And further research was conducted to analyze the uniformity of CF and the conductivity distributions of the as-prepared fiberboard.Cross-linked conductive network was observed to formation in the fiberboard with improved conductivity and SE remarkably. Percolation threshold decreased significantly with the increase of CF length. Volume resistivity of fiberboards decreased with the increase of CF lengths and filling amounts and tended to be stable at the CF filling amounts of 10%. It was found that SE of fiberboards increased with the increasing of CF lengths and filling amounts. It was also found that the modulus of rupture(MOR) and modulus of elasticity(MOE) was enhanced with the increase using of CF and then declined with the further addition of CF. And thickness swelling(TS) of fiberboards was increased with the increase of the CF length and filling amounts. Additionally, fiberboards containing CF of 5 mm in length exhibited noticeably comprehensive performance advantage between percolation threshold(0.75%) and steady value(10%) of CF filling amounts.Effect of fiberboard thickness on properties of the fiberboards was also investigated. Conductivity and SE of fiberboards was increased with the increase of the thickness of the fiberboard. SE of fiberboards with a thickness of 3 mm, 6 mm and 9 mm was 27.48~39.10 dB, 28.61~41.87 dB and 28.63~43.74 dB,respectively. And reached medium grade and indicated they could be used as effective shielding materials for electromagnetic radiations. MOR, MOE, internal bond strength(IB) and 24 h TS of fiberboards decreased with the increasing of fiberboard thickness and met the physical and mechanical property requirements of fiberboard determined by GB/T 11718-2009.