Investigation of the influence of production and processing mechanisms on the wood component of Wood Plastic Composites (WPC)
(Topic A.2)

– What happens to wood particles when being mixed with polymers
in a kind of heated meat mincer? –

The physical properties of WPC depend on different factors. The polymer type, the wood species, the use of coupling agents, impact modifiers, and other additives, for example, strongly affect the mechanical properties of the material. Also the shape of the wood, i.e., fibres, particles or flour, plays a crucial role. Wood fibres, for example, enhance the tensile and flexural properties of WPC due to their high aspect ratio. But particles are easier to disperse in the polymer and therefore lead to a more homogenous material.
In addition to the single WPC components, the processing is important, too. Depending on the production process and the process settings, the compounding of wood and polymer leads to a strong loading of the material caused by high temperatures and high shear stresses. Therefore, the process parameters have to be chosen according to the material composition. But simultaneously, the process parameters influence the constitution of the WPC components and hence the properties of the WPC.

The present PhD project investigates the influence of the production process on the wood component of WPC. Therefore WPCs are produced with different processes and process parameters are systematically varied. Afterwards, wood and polymer are chemically separated from each other and the wood component is analysed concerning its morphological constitution. The wood particles before and after processing are examined via optical dynamic particle analysis and changes in particle size and shape distribution are considered.
These experiments shall help to identify those process parameters which have a crucial influence on the wood component during WPC production and processing. The results lead to a better understanding of the process, help to optimize the process and facilitate the production of WPCs with well-defined properties.