Development of an optimal flax compound for large volume production processes
In May 2012, KU Leuven Kulab, Centexbel-VKC, Fi-sch-FPV, Celabor, IKV and Fraunhofer Darmstadt started a research project (CORNET) aimed at the use of short cut flax and hemp fibres to reinforce plastics and to be processed through conventional processes (injection moulding, extrusion, thermoforming).
The combination of the good specific mechanical and increased damping properties of this new compound offers many perspectives. The intensive collaboration between the partners resulted in the most appropriate finishing level of the flax to efficiently produce a standard and universally applicable compound. Next to the different processing parameters, such as shear viscosity and specific heat, the mechanical properties have been determined of the compound. On the basis of these properties, it is possible to support the designing process through digital simulation tools and to predict the mechanical performance of products.
Test specimens made by injection moulding demonstrated the impact of the injection moulding process on the fibre structure (orientation and length). It proved that the developed compound is universally applicable and that it can be processed within a large spectrum of processing parameters.
In the FlaxhemPlast project, several industrial products have been prototyped by using a matrix for a pallet designed for unfilled materials. The products fulfilled all expectations: the fibre processing of the flax compound was clearly noticeable in the injection moulded product because of its lower crimp level, other deformations of the product as a result of its anisotropic properties and higher mechanical strength. By means of the available digital simulation tools and material data, a new pallet design has been realised with a 20% weight reduction. Next to injection moulding, the flax compound has been subjected to extrusion tests to produce tubes and plates. The flax material gives the material a beautiful look and an increased stiffness. Because of these properties, industrial cases are being prepared, reckoning with the increased stiffness; Thermoform tests performed on extruded plates indicate that it is possible to process these new semi-products by thermoforming provided that the process parameters are adjusted to the material.
For more information on the project and its results, contact: Jan Hoogewys