Copper powder dispersed acrylonitrile butadiene styrene (ABS) composites were prepared by the solution cast method. Although the addition of Cu greatly enhanced the electric conductivity at the critical volume fraction (19:0þ=À1:0 vol%Cu) from the insulator to the electric conductor, the decrease in the Charpy impact value was gradual. Since the impact value of the ABS polymer prepared by the solution cast method was 1.75 times larger than that before treatment, it is clear that the solution casting improved the impact value. When the volume fraction of Cu powders of high electric conductive ABS composites was from 20 to 30 vol%Cu, the impact value was 7 kJm À2 . The moderated impact value was not only 44% of that of pure ABS polymer before solution casting, but was also higher than that of dispersed nylon6 composites (2 kJm À2 ) utilizeed for practical exteriors.

Cu powders dispersed ABS polymers were prepared by solution cast, which could easily control the dispersion ratio. The Cu addition gradually enhanced the electrical conductivity at less and more less than the critical volume fraction (19.0±1.0 volCu) in ABS polymer. The jump of electrical conductivity was observed by the Cu addition at the critical volume fraction. The result was explained by the percolation theory.

Cu powders dispersed poly methyl methacrylic acid (acrylic resin, PMMA) was prepared by solution cast, which could easily control the dispersion ratio. The Cu addition gradually enhanced the electrical conductivity at less and more than the critical volume fraction (15.0±1.0 volCu) in PMMA. The jump of electrical conductivity was observed by the Cu addition at the critical volume fraction. Although the result was mostly explained by the percolation theory, the critical Cu volume fraction to convert the high conductivity of PMMA composite is 4.0 vol lower than that of ABS composites.

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