Automotive Surr complex of 10 Years ago Published in bioplastics MAGAZINE Electronics Surround system of loudspeaker boxes with spherical shape: housing material Arboform of 10 mm wall thickness, lacquer coated Lignin Matrix Composites for Loudspeaker Boxes Article contributed by H. Nägele, J. Pfitzer, both of Tecnaro GmbH, Ilsfeld-Auenstein, Germany N. Eisenreich, W. Eckl, E. Inone- Kauffmann, E. Walschburger all Fraunhofer-ICT, Pfinztal,Germany B iocomposites obtained exclusively from renewable resources meet the requirements of sustainable processes and eco-innovation, and will expand future material research for engineering applications in industry. The properties, treatment and processing of these materials have to meet industrial standards concerning raw materials from biomass, fibres, wood extraction constituents and biopolymers, to enable their supply to mass consumer goods manufacturers, the construction industry, and the automotive and electronics industries. Thermoplastic matrices of composites include biopolymers such as polylactide (PLA), polyhydroxy-butyrate (PHB) and starch, as well as lignin from the paper industry. Reinforcement is carried out by the use of natural short fibres from hemp, flax and wood 1-4 . The natural polymer lignin is generated as a by-product of the pulp and paper industry, at a rate of approximately 60 million tonnes in chemical pulp mills every year, worldwide. This biomass extraction can also be carried out in an environmentally friendly way by using only water 5,6 . Thermal use of lignin for the power supply of the chemical pulp mills dominates its current utilisation rather than its use as a material for components. Its integration as a component in engineering materials has proven to be difficult 7,8 . However, recent work has succeeded in establishing lignin as the main component of a new class of engineering materials: Arboform®, based only on renewable resources, applicable for use in industrial equipment parts 9,10 . Technical advantages of these materials over synthetic polymers, such as the acoustic properties of lignin matrix composites (Arboform), could strongly support their application. The material consists of lignin, natural fibres for reinforcement, and natural additives to support processing and performance. It exhibits wood-like properties. Various sources of lignin - from different pulping procedures - and of natural fibres such as wood, hemp, flax, sisal, kenaf etc. - can be used. The choice of the lignin depends on the application field of the product. However, the material can be processed like a thermoplastic material and used for various engineering products. The processing includes: • Mixing of the constituents: ligni (30-60%) and natural additives mixer. • Pelletizing of the mixture at amb granules. This step avoids comp used for plastic compounds • Processing of the granules at rela by standard injection moulding ( facture parts This processing of lignin com on standard industrial injection m synthetic plastic resins. The tempe from 100°C in zone 1 to 170°C in z temperature can be between 155 and nozzle (2.5 – 4.0 mm). The back-pr high enough to enable a smooth rotat injection pressure is relatively high (>1 injection speed. The holding pressure of the machine’s capacity and the rela seconds. The cooling time must be ext compared to that of a synthetic thermo The mould tools should be desig production of special materials. Impor design should take into account: • The shrinkage on injection moulding i not exceed 0.3% • Core-pullers should be foreseen for d are useful to achieve fast working cycle • Hot runner nozzles work only in limited Depending on the fibre content the can vary between 2 and 8 GPa and th Strength between 2 and 6 kJ/m 2 , but the be extended to 16 by the use of impac elongation at fracture is between 0.3-0.6 expansion coefficient establishes below 5 no resonance frequencies are found and a of vibration leads to excellent acoustic pr enables the material to be used in loudspeak Two types of loudspeaker housings wer manufactured according to the procedures d The material itself exhibits a unique structu from part to part (see fig. 1). Original colour brown, green and red. Figures 2 and 3 show boxes including a lacquered surface finish. info@tecnaro.de eri@ict.fraunhofer.de Housing parts of the complex loudspeaker design as obtained directly from the mould 16 bioplastics MAGAZINE [<strong>04</strong>/08] Vol. 3 52 bioplastics MAGAZINE [<strong>04</strong>/18] Vol. 13
Automotive In July <strong>2018</strong>, Helmut Nägele Managing Director, Tecnaro says: ound system of loudspeaker boxes, shape: housing material Arboform with 5 mm wall thickness, lacquer coated n (40-70%), natural fibres (
Change language