Research On Fire Retardancy And Antistatic Property Of Wood Flour/Polypropylene Composites

It is necessary to conduct antistatic and fire retarding treatment for wood plastic composites (WPC) because whose main two components, thermoplastics and lignocellulosic materials, possess excellent electrical insulation properties and flammable properties, especially when WPC are applied in important areas of the operating rooms, electronic components workshops, etc. In this paper, the surface and volume resistance tester, limiting oxygen index analysis, cone calorimeter tests, thermal gravimetric analysis, scanning electron microscopy and mechanical properties tests and other research methods were used to analyze and discuss the antistatic properties, combustion properties, thermal degradation behavior and mechanical properties of the antistatic and fire-retarded wood flour/polypropylene (WF/PP) composites.The results of antistatic properties showed that the anionic antistatic agent SAS-93, conductive carbon black (CB) VXC72 and expandable graphite (EG) could decrease the surface resistivities of WF/PP composites to 109Ω and enhance the antistatic properties to different degrees. Synergistic antistatic effect existed between EG and conductive carbon black in composites materials, also WPC showed a phenomenon of "percolation threshold" when the addition amounts of EG and conductive carbon black were reach up to 10phr and 4phr, respectively. WF/PP composites displayed a good antistatic properties when conductive carbon black uniformly continuously distributed in a polymer matrix, and a certain distance between adjacent carbon black particles reached. The additions of SAS-93 and EG impaired the mechanical properties of the composites, however, CB could improve the impact strength of the composites derived from the reinforcement effect of CB.The heat and smoke release properties of WF/PP composites with EG were decreased and the residual mass was increased due to vermicular char layer generated by the flake of expandable graphite expanding under high temperature, delaying thermal degradation of polypropylene; polyphosphoric acid, produced by ammonium decomposing, catalyzed charring of wood flour at low temperatures and decreased the heat release of WF/PP composites, but the smoke release of APP/WF/PP was relatively large.A synergistic effect of fire retardants existed between EG and APP, could reduce heat release and smoke release, enhanced the quality of char layer and increased residu al mass of WF/PP composites significantly; the optimal proportion of blending APP:EG is 1:3; the addition of conductive carbon black enhanced fire retardancy of WF/PP and APP/WF/PP composites, however, excessive addition was not also conducive to the fire retardancy of expandable graphite; zinc borate increased the ignition time and resi dual mass, decreased the smoke release, WF/PP composites showed a good synergistic fire retardancy when the proportion of blending APP:ZB is 3:1; but the addition of SAS/APP/ZB impaired the mechanical properties of WF/PP composites.