Impact of mineral fillers on the properties of extruded wood-polypropylene composites

摘要

The main aim of this thesis is to study the effect of mineral fillers on the properties of extrudedwood-polypropylene composites (WPC). The studied minerals are Talc, Calcite (CaCO3), twoquantities of Wollastonite and Soapstone, and the level of mineral addition is 20 w-%. Thestudy shows that mineral fillers can be used to modify and improve the properties of woodplasticcomposites. Especially the moisture-related properties of WPCs were found to beimproved significantly by mineral addition. As the WPCs of the studied type are commonlyused in outdoor applications, this is of importance in terms of usability. In machining, theaddition of two minerals retained the surface roughness at same level throughout the test,indicating a favorable effect on machinability. The use of hard minerals shortened the tool lifein machining. In general, a modest increase in density was observed. In many of the studiedproperties, no apparent influence of mineral addition was found, indicating that the propertieswere not weakened. An overall result was that talc showed the best overall performance,indicating that it can be used as an active filler improving most of the studied properties,especially moisture resistance. Calcite was found to have nearly similar performance.According to the findings, mineral addition to wood-plastic composites appears to bebeneficial; especially moisture resistance can be enhanced without diminishing the otherproperties or usability in general.