Sustainable Sheet Moulding Compounds: Hemp Fibres Replace Glass Fibres

Sustainable sheet moulding compounds Panelling components: Hemp can replace glass fibres in many applications

2024-08-09 Source: Fraunhofer IWU 4 min Reading Time

Researchers at Fraunhofer IWU Zittau and Zittau/Görlitz University of Applied Sciences are developing sustainable sheet moulding compounds (SMCs) by replacing traditional glass fibres with natural hemp fibres. These new SMCs offer reduced environmental impact, lower CO₂ emissions, and fewer health risks for workers.

Close-up of a component made from natural fibre SMCs (inner train lining). The geometric degrees of freedom allowed by the material are clearly visible alongside the fibre structure.(Source: Fraunhofer IWU) — Close-up of a component made from natural fibre SMCs (inner train lining). The geometric degrees of freedom allowed by the material are clearly visible alongside the fibre structure.
(Source: Fraunhofer IWU)

Sheet moulding compounds (SMCs) are long-fibre-reinforced semi-finished products that can be used to produce complex moulded parts with high surface quality using the extrusion process. The Fraunhofer IWU Zittau and the Zittau/Görlitz University of Applied Sciences are researching biological alternatives for glass fibres in composite materials. The aim is to develop economical manufacturing processes so that the switch to less environmentally harmful biogenic residues for fibre reinforcement can be achieved soon. There are many possible applications for SMC components. They are used as interior panelling in trains and trains, exterior panelling for trucks and agricultural machinery or to protect electrical distribution boxes and switchgear.

Dr Rafael Cordeiro is a research associate at the Fraunhofer Plastics Centre Oberlausitz and in the Lander³ project at Zittau/Görlitz University of Applied Sciences. He is working in particular on train interior linings in which the glass fibre is replaced by natural fibres in combination with resin. The natural fibre used is hemp — more precisely, the coarser fibres that are a by-product of textile production using hemp. The weight proportion of natural fibres in the newly developed SMC is around 15 percent; the planned use of bio-based resin as a matrix, i.e. the component in which the fibres are embedded, will increase the “natural” proportion to up to 38 percent in future. Added to this are 55 percent minerals such as calcium carbonate (known as limestone or chalk) or aluminium hydroxide hydrate, which occurs naturally as bauxite. The remaining 7 percent are mainly petrochemical additives for which there is currently no bio-based substitute. The following are important facts about natural fibre SMCs.

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