What can be achieved by direct extrusion? Higher quality of the finished product by a less thermal impact, low production costs by an improved technology as well as increased flexibility in production.
A high product quality requires imperatively a very good dispersion of the wood fibres in the polymer matrix. Therefore on the one hand conventional compounding machines of different types in combination with a gear pump were used for the direct extrusion of wood polymer composites (WPC). On the other hand tests were carried out on a counter-rotating twin screw extruder. In addition to the modification of the screw design the application of static mixers was analysed. Both versions of direct extrusion achieved a good product quality with manageable investment costs.
Special attention was paid to develop the formulation. Within the scope of this, polymers, wood fibres and additives are varied in type and amount to find the optimal mixture. Furthermore different coatings and coating processes applying films, lacquers and powder coatings are investigated to make an acceptable durability in outdoor applications and a decorative appearance possible.
The projects 14181 BG and 16215 N were supported by AiF within the framework of the program for the promotion of industrial joint research and development (IGF) of the Federal Ministry of Economics and Technology. We kindly acknowledge the financial support.
You can obtain the research report with full details here.