Novel process development in post-forming of an extruded wood plastic composite sheet

Abstract

The demand for the utilization of plastic waste has increased due to the tightening environmental legislation and interest in material recycling. Wood plastic composites are one possible way to recycle thermoplastic materials, as they have desirable material properties for many applications. However, due to technical restrictions and lack of knowledge, the product geometries have been mainly limited to extruded twodimensional profiles. In this work, the development of post-processing and line development methodology for an extruded thermoplastic wood plastic composite is investigated to enable the production of more complex shapes. The aim of the work is to investigate and recognize the major factors affecting the post-processing of the composite material by utilizing the press forming technique, and to develop a practical prototype line based on these observations and findings. Several experiments are done to investigate the most influential material properties and parameters of one interesting thermoplastic composite material. In this process, the main challenge in acquiring satisfactory quality of a complex product is uniform temperature control of the process and the adhesion properties of the composite material. The results show that the quality of extruded, press-formed thermoplastic wood plastic composite products can be satisfactory and suitable for mass production, if right parameters are selected for the machine construction, and the process temperature is monitored and controlled. It is also shown that the mechanical post-processing stage can decrease material variation and thus improve the quality of the extruded sheets. However, the material fabrication stage is still in a great role for determining the final product quality. Utilizing the method presented in this work makes it possible to develop post-processing lines for other wood plastic composites and analogical materials.