Experimental samples of biodegradable composite material based on polylactide and wood filler, subjected to thermal modification, were obtained. When studying the samples a change in such properties as the rate of biodegradation and tensile strength was observed. It has been established that the degree of preliminary thermal treatment of wood filler can control the rate of biodegradation in the material, which can be used in the production of biodegradable packaging. Depending on the desired product life cycle, packages with an adjustable decomposition time can be created. It is found that with an increase in the degree of heat treatment of the filler in a composite material with more than 40 % of polylactide the tensile strength decreases, while with a lower binder content thermal modification has a positive effect on the strength. Also, adding the fillers can significantly reduce the cost of composite material.

Composite materials based on wood filler are promising materials that are actively conquering the market. This is due to the advantages of using these materials in various fields: weather resistance and environmental compatibility, easy machining and possibility of recycling. Furthermore, it is sustainable use of wastes of timber sawing and furniture and woodworking industries, as well as low-grade wood. Wood powder is also known to be one of the components of consumables used in additive 3D printing technologies. Over the last decade, the commercial use of 3D printers has increased rapidly due to the fact that it allows creating prototype objects of complex shape based on a computer model. Experimental studies were carried out to determine the tensile strength and rheological properties of a composite made of polylactide 4043D, untreated wood powder brand 140 and wood powder thermally modified at 200 and 240 °C. The composite is intended for creation of three-dimensional objects by extrusion using a 3D printer. It was found that with an increase in the amount of filler in the composite, the tensile strength decreases. Also, samples with thermally modified filler show an increase in tensile strength in comparison with samples with untreated filler. Prototypes of 3D threads with different composition were obtained, during the study of which the melt flow index was examined. It was found that with increasing temperature of wood filler treatment the melt flow index increases. With a lower content of wood powder in the melt composition, there is a 2-fold increase in the melt flow index. The knowing of the rheological properties of the resulting compositions will allow achieving maximum performance and reduction of energy and production costs.

In environmental matters, one of the most pressing problems is the efficient disposal of polymeric materials that have a negative impact on the ecology of soils and oceans. A necessary condition for the sustainable development of industrial production and processing of polymer products is the transition to polymer materials based on renewable plant raw materials, in particular polylactides, polyhydroalkanates, etc. However, the technology for the production of these types of polymers is seriously inferior to synthetic polymers in the field of energy engineering. In this regard, research in the field of creating composite materials by introducing wood filler is currently particularly relevant. This research covers the results of stress-strain behavior of wood filled polylactic wood powder composite materials thermally modified by high temperatures ranged from 200 to 240 °С. Wood impact strength dependence is defined and static bending and composite density dependence on wood filler quantity and the temperature of its thermal modification is also established. It was specified that with the increasing of filler densification and its thermal treatment, the wood impact strength and composite density is decreasing, while with the reduced content of binding, the thermal modification of 200 °С has a positive impact on bending elastic coefficient. The conducted research allows identifying rational areas of use of composite materials as an effective factor in managing natural resources.

This paper presents the findings of experimental studies of the physical and mechanical properties of wood-filled composites based on polylactide (PLA) and vegetable filler in the form of wood flour (WF) thermally modified at 200-240 °C. It also reveals the dependence of the tensile strength, impact strength, bending elastic modulus, and density of composites on the amount of wood filler and the temperature of its thermal pre-modification. We established that an increase in the concentration of the introduced filler and the degree of its heat treatment results in a decrease of the tensile strength, impact strength and density of composite materials, while with a lower binder content, thermal modification at 200 °C has a positive effect on bending elastic modulus. We also found that 40 % content of a wood filler heated to 200 °C is sufficient to maintain relatively high physical and mechanical properties of composite materials. With a higher content of a wood filler, the cost can be reduced but the quality of products made of this material may significantly deteriorate. However, depending on the application and the life cycle of this product, it is possible to develop a formulation that includes a high concentration of filler.

No abstract