SaferWorldbyDesign: Lignin-based Materials Development and Manufacturing according to SSbD principles
Speakers: Gerard Fernando (University of Birmingham & Ghada Targorti (Edelweiss Connect)
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Environmentally Friendly Filament Winding & Sustainable Carbon Fibres
This presentation is based on ongoing research that is being undertaken under the remit of the project entitled “Multifunctional biophenols for safe and recyclable materials” (BioPhenom). The project is funded by the European Commission (Grant Agreement No: 101135107), Innovate UK (Grant Agreement No: 1005409) and Swiss State Secretariat for Education, Research and Innovation (Grant Agreement No: 24.00212). The overall aims of the BioPhenom project are: (i) to replace substances of very high concern with bio-based alternatives; and (ii) the development of safe, sustainable and recyclable materials, and manufacturing processes.
This presentation consists of two inter-related themes. The first part of the talk will focus on the development and on-site demonstration of an environmentally friendly filament winding (EFFW) technique for the production of fibre reinforced pipes and pressure vessels. The second part will address the production of carbonised nano-fibres using two classes of naturally occurring biopolymers, namely, lignin and tannin. The link between the two sections is the development of bio-based carbonised fibres and bio-based resin systems. These bio-based materials will be substituted for synthetic carbon fibres and thermosetting resins. A small filament wound component will be manufactured using these bio-based materials in conjunction with the EFFW manufacturing process.
Conventional filament winding is an established manufacturing technique for the production fibre reinforced composite pipes and pressure vessels. In this manufacturing process, the reinforcing fibres are impregnate using a resin bath and the impregnated fibres are wound onto a rotating mandrel, and subsequently, the resin system is cross-linked. This manufacturing has a number of issues that need to be addressed. Firstly, the components of the resin system (for example, an epoxy resin and a cross-linking agent that is referred to colloquially as the hardener) have to be weighed out manually to the required stoichiometric ratio, and mixed thoroughly until a visually assessed homogeneous colour is determined. The resin bath has to be topped up manually as the liquid level drops as a function of the processing time. Due to the nature of the manufacturing process, the impregnated fibre have to be traversed back and forth across the rotating mandrel; this causes in the impregnated fibres to rub against the guide pins leading to the resin dripping on to the shop floor. In order to alleviate these issues, in the EFFW process, the fibres are spread to reduce their thickness (to accelerate the impregnation rate). Instead of using a resin bath, the resin and hardener are stored separately and are pumped via precision gear pumps to a static mixer; this negates the need for manual weighing and mixing and the desired stoichiometry for the resin and hardener is achieved. A custom-designed impregnation device is used to deliver the required quantity of the mixed resin system to the spread fibre bundles. The design of the impregnation unit is such that its volume is significantly smaller that a conventional 5 litre resin bath. The primary advantages of the EFFW manufacturing process when compared to the conventional method are: (i) manual topping up of the resin bath is not required; (ii) the stoichiometry of the resin and hardener is assured with the possibility of human error eliminated; (iii) the dripping of the from the impregnated fibres, at every contact point with the equipment (fibre guides, guide pins, D-eye) is reduced; (iv) the impregnation unit can be retrofitted on the resin bath or the traverse arm or in close proximity to the rotating mandrel; (v) it requires a fraction of the volume of solvent that is required to clean the equipment at the end of production; (vi) the volume of residual resin retained in the impregnation unit is reduced significantly; and (vii) the time required to clean the equipment for the EFFW methods is reduced significantly.
Carbonised fibres from lignin and tannin: The primary precursor that is used for the production of reinforcing carbon fibre is acrylonitrile. This precursor is derived from petroleum and it is associated with a number of hazard numbers/statements: H225 - Highly flammable liquid and vapor. H301 + H311 + H331 -Toxic if swallowed, in contact with skin or if inhaled. H315 - Causes skin irritation. H317 - May cause an allergic skin reaction. H318 Causes serious eye damage. H335 May cause respiratory irritation. H350 - May cause cancer. H411 - Toxic to aquatic life with long lasting effects. Therefore, it was considered as an idea candidate for a BioPhenom case study to consider options to replace it with relatively inert precursors that are derived from biomass. The candidate materials selected were lignin and tannin. The aim of this study is to implement the framework of Safe and Sustainable by Design (SSbD) established by the JRC in a case study on lignin to support future studies using biophenols as potential substitute chemicals. Herein, we investigated the data gaps, and the challenges encountered to perform Steps 1-3 to determine the safety of lignin and compare it to the reference compound known as acrylonitrile. By applying this framework more targeted decision-making could be supported as substituted lignin is still in the early stage of innovation.
The micrographs below demonstrate that lignin and tannin fibre can be produced by electro-spinning and that they can be carbonised. The next task is to enhance the mechanical properties of these fibres. Follow-on research will be reported at a later date where bio-based and recyclable filament wound tubes will be demonstrated.
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Figure 1(a and b): (a) As-spun lignin fibres after drying at 100 ⁰C for 4 hours; and (b) oxidised at 260 ⁰C for 2 hours and carbonised fibres at 1200 ⁰C for 2 hours.
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Figure 2(a and b): (a) As-spun tannin fibres after drying at 100 ⁰C for 4 hours; and (b) oxidised at 260 ⁰C for 2 hours and carbonised at fibres 1200 ⁰C for 2 hours.
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Environmentally Friendly Filament Winding & Sustainable Carbon Fibres
Siheng Shao¹, Ghada Tagorti², Zi He¹, Rohit Jassi¹, Claire Wait¹, Shafiq Irfan¹, Ramani S. Mahendran¹, Dee Harris¹, Surya D. Pandita¹, Venkata Raj Machavaram¹, Barry Hardy², Mark A. Paget¹, Zoe Schnepp³, Samuele Giovando⁴, Petri Widsten⁵, Melissa Agustin⁵, Marc Borrega⁵, Aratz Genua⁶, Mayorkinos Papaelias¹, and Gerard F. Fernando¹*
¹ Sensors and Composites Group, School of Metallurgy and Materials, University of Birmingham, UK
² Edelweiss Connect, Technology Park Basel, Hochbergerstrasse 60c, 4057 Basel, Switzerland
³ School of Chemistry, University of Birmingham, UK
⁴ SILVATEAM, via Torre 7, 12080 San Michele Mondovì CN, Italy
⁵ VTT Technical Research Centre of Finland Ltd., Tekniikantie 21, VTT, P.O. Box 1000, FI-02044 Espoo, Finland
⁶ CIDETEC, Basque Research and Technology Alliance (BRTA), Paseo Miramón 196, Donostia-San Sebastián 20014, Spain
* Corresponding author
