The aviation sector increasingly prioritises sustainability, necessitating the development of
environmentally friendly materials. Polymer matrix composites (PMCs), widely utilised in
aerospace for their excellent strength, stiffness and low weight, predominantly rely on petroleum
derived epoxy resins. These resins pose significant environmental concerns, including dependency
on non-renewable resources, health risks, and limited recyclability. This thesis explores the
feasibility of bio-based resveratrol epoxy resin as a sustainable replacement for commercial epoxy
monomers. A comparison with commercial Tactix 742 monomer is motivated by its application in
areas requiring high thermomechanical performance, a niche that RTE has the potential to fill.
Furthermore, RTE is also compared with BADGE as the most common commercial monomer, as
well as other bio-based monomers. Derived from renewable sources such as knotweed, resveratrol
offers a trifunctional aromatic structure with the potential to achieve high thermal and mechanical
properties while reducing the environmental burden of epoxy.
The study entailed the synthesis and detailed characterisation of resveratrol epoxy resin, assessing
thermal, physical, and mechanical properties. Results demonstrated a bio-based content of 74%
compared to 25% of the T742-based analogue, indicating the resin's strong potential as a renewable
material. Thermal analysis revealed a high glass transition temperature (Tg) of over 300°C and
thermal resistance of up to 350°C, outperforming aerospace-grade commercial epoxies.
Mechanical testing highlighted the resin's excellent performance, including fracture toughness
47% higher than analogue T742 resin. Furthermore, additional mechanical testing of composite
panels showed RTE's usability in composite structures.
The findings confirm that resveratrol-based epoxy resin offers a sustainable, high-performance
alternative to traditional petroleum-based matrices. It also tackles some common bio-based epoxy
issues, such as hydrophilicity and low thermal stability. Recommendations for further
optimisation, including viscosity reduction, further cure kinetic characterisation and thermal
performance investigation, are provided to facilitate the broader adoption of bio-based
thermosetting systems in aerospace and other high-performance sectors.

The aerospace sector continues to drive innovations in high-performance materials. These materials however, tend to have energy intensive and emission heavy manufacturing processes. One of the most commonly used materials in aircrafts today are polymer matrix composites consisting of reinforcement fibers and a matrix. While the fibers provide the most strength to the composite, the matrix holds the fibers together and transfers the loads to them. The most commonly used matrix material today is made of BADGE (Bisphenol A Diglycidyl Ether), a material which is toxic to humans and comes from fossil-based products.

This thesis investigates the viability of a vanillin-derived bio-based alternative, VDE (Vanillyl Alcohol Diglycidyl Ether), to be used in high-performance composites for aerospace applications. VDE monomer is derived from vanillin, which is obtained from lignin, a material present in 35% of woody plants. The VDE-DDS resin system, when cured, exhibited comparable thermal and physical properties, such as glass transition temperature and heat deflection temperature, to traditional aerospace resins like BADGE-DDS. Mechanical testing, including tensile, flexural, and fracture toughness, demonstrated promising results, with VDE-DDS showing higher strength and modulus than BADGE-DDS. The flexural strength was considerably higher in particular. However, its hydrophilic nature led to higher water absorption, a challenge for long-term durability. For further testing, composite specimens were prepared using an autoclave.

Composite specimens reinforced with VDE-DDS displayed greater stiffness and strength under mechanical testing compared to BADGE-DDS in tests of in-plane shear strength, compression and inter-laminar shear strength tests, though BADGE-DDS composites outperformed in low-velocity impact resistance. The impact testing also revealed that BADGE-DDS samples had a higher damage initiation energy while VDE-DDS samples had a higher bending stiffness. Overall, VDE-DDS offers comparable, if not better, thermal and mechanical characteristics to BADGE-DDS. VDE, in summary, presents a compelling case as a potential bio-based alternative for structural aerospace applications.