Preparation And Properties Of Both Conductive And Flame Retardant Properties Of Polypropylene Matrix Composites

The composites with conducting property and flame-retardant performance based on polypropylene were prepared, using expanded graphite and expandable graphite as addition agents. The surface treatment agent and its best handling capacity were confirmed. The effect of filler content on conducting property, flame-retardant performance, mechanical property and rheological behavior was studied. The dispersible state of the filler in the composites was studied by means of SEM. The conductivity of the composites reaches to the threshold value when the adding content of expanded graphite was 10wt%, expandable graphite was 10wt% or expandable graphite was 25wt%, expanded graphite was 10wt%. The threshold value (Ω·cm)is in the same order of magnitude, i.e. 10~6. It is indicated that expandable graphite has certain contribution to the electric conductivity. By means of the test of LOI (limited oxygen index), it is showed that composites have good flame-retardant characteristics and expanded graphite has less contribution to the flame -retardant effect. The addition of filler slightly strengthens composites' tensile strength. When the filler content is lower than the threshold, filler particles show some reinforcing effect to the impact strength; but the impact strength decreases slightly when filler content is higher than the threshold. The SEM microphotographs turn out that filler particles are dispersed homogeneously in the matrix to form continuous conducting network at threshold value. With the increase of filler amount, the rheological property of composites decreases. The die swell phenomenon of the composites was studied. At lower shear rate, the fluid viscosity of composite has more sensitiveness to temperature.