The main objective of this thesis is to study the impact of different mineral fillers and fireretardants on the reaction-to-fire properties of extruded/coextruded wood-plastic composites(WPCs). The impact of additives on the flammability properties of WPCs is studied by conecalorimetry. The studied properties are ignition time, peak heat release rate, total heat release,total smoke production, and mass loss rate. The effects of mineral fillers and fire retardants werefound to vary with the type of additive, the type of additive combinations, the amount ofadditives, as well as the production method of the WPCs. The study shows that talc can be usedto improve the properties of extruded WPCs. Especially ignition time, peak heat release rate andmass loss rate were found to be improved significantly by talc. The most significant improvementin the fire retardancy of coextruded WPCs was achieved in combinations of natural graphite andmelamine. Ignition time, peak heat release rate and total smoke production were improvedessentially. High increase in smoke production was found in samples where the amount ofammonium polyphosphate was 10% or higher. Coextrusion as a structural modification wasfound as a promising way to improve the flammability properties of composite materials in acost-effective way.
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