Characterisation and Selection of Sustainable Discontinuous Natural Fibre Reinforced Polymer Constituents and Their Composites

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


The increasing societal concern about the environment leads to a focus on sustainability in many engineering fields, including fibre reinforced polymer matrix composites (FRPs). Due to their non-environmentally friendly constituents, i.e. thermosets and synthetic fibres, this sector is committed to researching sustainable solutions. Two different approaches can be considered for possible solutions. The first approach is reducing the environmental impact of constituent materials by using sustainable raw materials, such as natural fibres and bio-based matrices. The second approach is reducing landfill waste by considering a “repair, reuse or recycle” approach for composites. Because the composite industry uses mostly thermoset matrices, which form irreversible bonding mechanisms when cured, it is difficult to apply the second approach. However, thermoplastic matrices or covalent adaptable network polymers can overcome this and make it easier to apply the second approach. Furthermore, changing the fibre reinforcement geometry from continuous to discontinuous promotes and facilitates the concept of repair and reuse, which are quite difficult to achieve with continuous FRPs. This is because after the possible repair or reuse process, factors such as manufacturing defects and flaws will be altered so that all performance predictions for the original product will become invalid; alternatively, those of discontinuous FRPs remain relatively the same. Moreover, highly aligned discontinuous FRPs produced with the High-Performance Discontinuous Fibre (HiPerDiF) method can show performance comparable to continuous FRPs. In this study, a number of plant-based natural fibres (curaua, flax, jute, kenaf) and potentially sustainable matrices (Elium®, Furacure, Vitrimax™) are investigated to be selected as sustainable and feasible constituents for a sustainable aligned discontinuous FRP produced with the novel HiPerDiF method. It is found that short flax fibres and a vitrimer resin are the best constituents for future sustainable aligned discontinuous FRPs studies due to promising mechanical performance and offering a circular economy via repair option in composite applications.
Date of Award5 Dec 2023
Original languageEnglish
Awarding Institution
  • The University of Bristol
SponsorsThe Republic of Turkey Ministry of National Education
SupervisorSteve Eichhorn (Supervisor), Ian Hamerton (Supervisor) & Marco L Longana (Supervisor)

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