Cellulose from waste and bacteria in electro-spinning for continuous fibre reinforced 3D printed composites

Thermoplastic filaments for 3D printing are usually reinforced with various types of fibers, including natural ones. Natural fibers represent an environmentally friendly approach to filament functionalization due to their high strength/stiffness to weight ratio and low carbon footprint; in combination with a biodegradable matrix, they thus enable the production of a fully biodegradable 3D printed material. Usually, the reinforcing fibers are cut very short, which affects the mechanical properties of the final 3D printed product. Recently, the approach of adding continuous reinforcing yarns to the filament design has emerged, which provides greater strength and stiffness, but its addition represents a major challenge for the 3D printing process. The BioCel3D project proposes the incorporation of cellulose reinforcement into the structure of 3D filaments, with cellulose fibers obtained from agricultural and industrial waste and cellulose obtained through bacterial cultivation. The use of waste materials as raw materials supports the circular economy. The BioCell3D project aims to develop a "green" continuous fiber additive technology for 3D printing of materials for advanced applications. The proposed material will address 3 main characteristic shortcomings of natural fibers for use in composites: i) moisture sorption, ii) natural variability (mechanical properties are different even for the same type of fiber) and iii) technical fiber mismatch at the yarn level. The printed composites produced will represent environmentally friendly products that will contribute to meeting recycling requirements. We expect high R&D applicability of the project results, as techniques will be established to combine low-cost sustainable substrates with highly functional properties for the development of advanced composite materials, which are at the forefront of basic and applied materials research.

BioCel3D has the ambition to develop a brand-new generation of reinforced cellulose fibres with high mechanical properties for the design of complex 3D printed composite materials. To do so, the partners of this innovative M-ERA.NET project coordinated by LIST will make use of recycled cellulose. From textiles industries to agricultural waste as well as bacterial cellulose, the University of Maribor and Graz University of Technology will focus on the production of nanocellulose from these recycled raw materials. While KU Leuven will provide molecular dynamic simulations, LIST will build up the cellulose fibres by electro-spinning of the nanocellulose together with cellulose derivatives. Other biomaterials, such as dopamine, will be used with the elemental fibres within the interface in order to obtain technical fibres exempt of the usual natural fibres limitations. LIST will carry out the mechanical tests on the cellulose fibres before producing the filaments that will be used by KU Leuven for the 3D printing of composite materials.