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Natural Fibre Composites

Natural Fibre Composites Fig. 3. CTAG laboratory of plastic injection (right) and injected probes of reinforced polypropylene with different natural loads coming from forest residues (left). the results with a commercial compound of polypropylene reinforced with 20% of glass fiber (Hostacom NO1L G2) that already meets these requirements. Preliminary results of this study indicate that the use of natural fibers from forestry waste as reinforcement for the development of fully functional parts in the automotive sector could be viable. Although not all materials are optimal for this type of development, some of them exhibit properties completely comparable to commercial products accepted in the industry. Both the previous processing step of the natural load and its concentration are the main determinants of the final properties of the compounded material. In fact, each type of natural filler presents its optimal processing conditions and concentration. Therefore, further progress in the identification of new processing methods as well as in determining new materials to maximize compatibility between the natural load and the polymer, is needed. Although manufacturing processes of this type of compounds still have to be refined, the benefits of including natural fillers on the formulation of plastics are very clear. In one hand, composite materials from forest residues retain the mechanical properties of the polymer matrix, reducing by about half the use of non-renewable sources. Besides, the cost of fabrication is reduced by 30%. On the other hand, it also opens a new opportunity for intersectoral collaboration that optimizes the exploitation of natural resources of the region and significantly reduces the environmental impact inherent in the manufacturing process of plastic materials. Project co-financed by the Galician R & D supporting program (INCITE) with ERDF funds. Fig. 4. Some of the composite validation tests available on CTAG installations. From top to bottom: mechanical tensile test, bending test and complete vehicle climatic chamber. 40 bioplastics MAGAZINE [03/12] Vol. 7

Natural Fibre Composites The results of a project promoted by the DBU, (Deutschen Bundesstiftung Umwelt; the German Federal Foundation for the Environment), entitled ‘Development of industrial scale natural fibre pellet production using natural fibres to reinforce bioplastics in injection moulding and extrusion techniques’ has generated significant interest within the industry. Compounders, injection moulders, extruders and users from the plastics and automobile industries have expressed great interest in the use of natural fibre pellets with hemp fibre reinforcement. Production and optimisation of so-called ‘soft pellets’ to resolve the problem of dosing natural fibres in plastic industry processing was achieved by project partner BaFa (Malsch, Germany). The extensive range of trials by industry partners FKuR (Willich, Germany), Linotech (Waldenburg, Germany) and H. Hiendl (Bogen, Germany), as well as by the Fraunhofer WKI (Braunschweig, Germany), which were evaluated by the Bremen technical university in Germany, showed that natural fibre pellets can not only be accurately dispensed but also blend well and evenly into the melt. Prof. Dr. Jörg Müssig (Univ. Bremen, Bionik) and his team tested the properties of hemp fibres before and after pelletisation, within the granulate Hemp fibres and hemp fibre pellets (photo: nova-Institut GmbH) Breakthrough in injection moulding of natural fibres and in the end product, as well as checking the mechanical values of test pieces and end products. It was only in this way that the project could ensure a progressive improvement in the natural fibre pellets Project leader Michael Carus of the nova-Institute (Hürth, Germany) expressed his satisfaction: “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 hard 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 as well as pellets that during pelletisation have been blended with 40% of a plastic such as PP or PLA, as well as having additives included as required. A surprising result of the project is that pellets made from 60% natural fibre and 40% PP were able to be fed directly into the extruder without compounding, which saves a significant level of cost. The nova-Institute tested the pellets with regard to the process energy used and with regard to their anticipated market price. Here it was seen that the market prices depend up to about 75% on the material cost (hemp fibres and, where relevant, plastics). Depending on the composition, prices for natural fibre pellets lie between 0.80 and 1.20 Euros per kg, which for most companies would be an attractive price as a solution to their infeed problems. Bernd Frank, managing director of BaFa GmbH, has been enjoying a lively level of interest since these results were made public. The pelletisation plant is already running at a high rate to produce natural fibre pellets to customer’ requirements, with and without plastics or additives. MT In-feed in the form of fibre pellets solves dispensing problems bioplastics MAGAZINE [03/12] Vol. 7 43

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