The effects of processing on performance and utility in plant fibre-based composites

The global concern about the growing consumption of non-recycled plastics has led material scientists to explore alternative materials for the development of environmentally friendly products that can be recycled or re-used. Natural fibres and biodegradable polymers are renewable materials that can be used for composite manufacturing. In this study flax and nettle fibre-reinforced Floreon composites were made using traditional and new developed techniques. Flax and nettle fibres of two different preparation processes were used as reinforcing materials. The physical, mechanical, and thermal properties of industrially and minimally processed flax and nettle fibres were studied, showing a clear species and preparation-based differences on the fibres’ properties. Flax and nettle single fibres were prepared properly and blended with Floreon using extrusion. Flax and nettle fibre-reinforced Floreon composites were then made by injection moulding. The relationship between the fibre type, content, and processing parameters was investigated. It was found that composites consisting of minimally processed fibres had increased mechanical properties compared to composites made by the respective industrially processed fibres. The appropriate processing parameters for composites were established for the different fibre types. The physical and mechanical properties of 3D printed flax and nettle fibre reinforced Floreon composites using fused deposition modelling were also investigated. The 3D printed composites showed greater tensile and flexural strength results compared to the injection moulded composites. The effects of fibre type, content, printing parameters such as nozzle temperature, fill density, layer height thickness and pattern orientation were experimentally studied. It was found that with increasing flax and nettle fibre content, the mechanical properties of composites produced increased. The environmental sustainability of flax and nettle fibres, Floreon, and composites produced were analysed using life cycle assessment methodology. The environmental analysis was used to evaluate the emissions of each raw material used, the energy and materials requirements during composite manufacturing.