A recent project carried out by the nova-Institut (Hürth / Germany; www.nova-institut.eu), to develop industrial scale natural fibre pellet production to reinforce bioplastics in injection moulding and extrusion, has generated significant interest within the industry, the institute has said. At an event held in May 2012 in Cologne / Germany, compounders, injection moulders, extruders and users from the plastics and automobile industries expressed great interest in the hemp fibre pellets. Production and optimisation of the natural fibre pellets to resolve the problem of dosing natural fibres in plastics processing was achieved by project partner hemp straw supplier Badische Naturfaseraufbereitung (BaFa, Malsch / Germany; www.bafa-gmbh.de).

Extensive trials were carried out by industry partners including German bioplastics compounding specialist FKuR (Willich; www.fkur.com) and the Fraunhofer Institute for Wood Research (Fraunhofer WKI, Braunschweig / Germany, www.wki.fraunhofer.de) and showed that natural fibre pellets can not only be accurately dispensed but also blend well and evenly into the melt. The properties of the hemp fibres were tested before and after pelletisation, within the granulate and in the end product, as well as checking the mechanical values of test specimens and end products.

Project leader Michael Carus of the nova-Institute said: “At last the bottle-neck presented by natural fibre infeed has been overcome. Now even companies with relatively little experience can dose natural fibres in pellet form. The pellets are already firm enough to resist the stresses of transport and storage, and soft enough to blend well into the melt.”

The producer, BaFa, offers pure natural fibre pellets, those that during pelletisation have been blended with up to 40% of a plastic such as PP or PLA, as well as pellets containing additives if required by the customer. The project also showed that pellets made from 60% natural fibre and 40% PP were able to be fed directly into the extruder without previous compounding, which saves a significant amount of cost and process energy.