Effect of the processing on the properties of biopolymer based composites filled with wood flour

Abstract

Wood-polymer composites (WPCs) are well known today in the field of industrial applications, because of several advantages they can grant if compared with mineral filler-polymer composites. These advantages regard the low cost of wood based fillers, the reduced specific weight, the lower hazards for production workers in case of inhalation, the special aesthetic features, environmental issues. The scientific literature reports studies regarding polymer matrices like, for instance, polyethylene and polypropylene, in combination with several natural-organic fillers. However, a limit of these composites is represented by the fact that there is not a full biodegradability: this, in fact, regards only the filler, therefore the environmental performance is lower than expected. To overcome this limit, it is necessary to replace the traditional, nonbiodegradable polymer matrices (typically, polyolefins) with biodegradable ones. An available solution consists in the use of biodegradable polymers like, for instance, those belonging to the Mater-Bi® family.

In this work, a biodegradable polymer matrix, coming from the Mater-Bi® class, was mixed with a naturalorganic filler, wood flour. The investigation was focussed on the comparison between different processing ways (single-screw extruder, twin-screw extruder; compression moulding, injection moulding), in particular the relationships between the mechanical properties and the processing method, the filler type, the humidity content of the components were analyzed. Morphological characterization was also carried out by SEM analysis, in order to get further indications regarding some different behaviours shown by the processing methods and the fillers.