This research investigates the feasibility of bamboo fibre-reinforced bio-derived polycarbonate composites for secondary aerospace applications. Motivated by the need for sustainable alternatives to synthetic composites, the study focuses on the effects of chemical fibre treatments on mechanical, thermal, and interfacial performance. Bamboo fibres were treated using alkali (2–8% w/v), silane (2-8g/L), and acetylation methods. Acetylated fibres were excluded early due to structural degradation.

Comprehensive fibre characterisation included density, water absorption, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and single fibre tensile testing. Notably, 2% NaOH-treated fibres exhibited a tensile strength of 249 MPa, and 5 g/L silane-treated fibres reached 194 MPa, compared to 110 MPa for untreated fibres. TGA showed improved thermal stability with onset degradation temperatures of 277◦C for 5 g/L silane compared to 267◦C for untreated fibres.

Treated fibres were used to fabricate unidirectional laminates via solvent-based prepreg processing with Durabio, followed by compression moulding. Composite testing included tensile, flexural, and microscopic cross-sectional analysis. The highest tensile strength of 162 MPa and flexural strength of 184 MPa were recorded for composites with 2 g/L silane-treated fibres, with 5 and 8 g/L silane laminates being only slightly lower than that. Untreated composites recorded 121 MPa and 154 MPa, respectively. Void content decreased from 21% for untreated to 18% for silane-treated, accompanied by a bonding efficiency of 95% for the 5 g/L silane laminate, indicating significantly improved fibre-matrix bonding efficiency. This was supported by optical microscopy, which showed more cohesive interfaces and reduced delamination in silane-treated laminates. Alkali-treated fibres, however, consistently showed worsening properties and quality on the composite level due to fibre degradation and poor bonding.

The study concludes that silane treatment, particularly at 2 g/L, enhances fibre-matrix compatibility, leading to superior composite performance. Future work is recommended in areas including environmental durability, manufacturing optimisation, and closed-loop recycling, with potential expansion to other bio-based matrices. ... Read more

Due to rising global temperatures from climate change, wildfires have now become ever more frequent and devastating in Europe. A particular strategy for wildfire mitigation is containment, where a barrier is created to prevent the spread of a wildfire without necessarily actively suppressing it. To this end, aerogel emerges as a novel and high-performance material for such barriers given its lightweight and extremely insulating properties. AeroShield, a system consisting of a swarm of autonomous UAVs to contain wildfires by deploying aerogel blanket barriers, is a solution to leverage aerogels’ properties for a rapid response to spreading wildfires. Additionally, given the extremely hydrophobic and equally lipophilic characteristics of aerogel, the same system can be used in an entirely different market: oil spill absorption and containment. The system uses fixed wing VTOL UAVs with a span of 3 meters, which deploy the aerogel in blanket form. It can operate in temperatures up to 140 degrees celsius and 30 km/h wind speeds. The deployment rate for a 3 meter wide fire break is 24 meters per hour, and it is capable of absorbing 950 kg of oil per hour. ... Read more

Twin matrix composites consists of fibre bundles impregnated by a hard matrix. These bundles are then embedded in a flexible polymer to increase the transverse failure strain of the laminae, but a tougher flexible matrix should also provide better impact resistance. In this thesis, a twin matrix composite is made using carbon pultrusions embedded in a vitrimer, and its behaviour under impact is tested using a quasi static indentation test and compared to a traditional unidirectional laminate. The twin matrix composite exhibits higher deflection, and a non destructive test using ultrasounds revealed lesser delamination area at the same energy and strain rate than the UD one. ... Read more

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. ... Read more

Nowadays, Hydrogen production is an important piece in energy transition system and holds a significant place in various industries. This gas is precursor for producing valuable compounds in the chemical industry and serves as a clean fuel, enabling efficient electricity generation when used with fuel cells. However, majority of its production still relies on reforming and gasification of non-renewable sources. A sustainable pathway for Green Hydrogen production through water electrolysis already exists. However, scaling up and commercializing this technology represents challenge in meeting global demand, which was reported to be around 95 million tonnes in 2022. Commercially available water electrolysis done in acidic environment is robust, however rather expensive. Anionic Exchange Membrane Water Electrolysis (AEMWE) is available alternative, but still not fully developed to be used on big industrial scales. AEMWE offers reduced cost as this technology does not require usage of expensive noble metal catalysts used in acidic electrolysis. Focus of the AEMWE research area is Anionic exchange membrane (AEM) as high values of conductivity of hydroxide ions could lead to fair technical competitiveness of alkaline and acidic electrolysis. However, the majority of currently available AEMs lack the desirable properties, such as mechanical/alkaline stability as well as anionic conductivity.
One of the promising novel techniques for membrane fabrication consists of membrane casting with employing DC electric field, which enhances charged polymer channel orientation. Reports have shown that polymer ion channels in random direction may cause slower migration and consequently lower values for conductivity. On the other hand, it has been proven that DC treated membranes can yield up to three times higher values for conductivity of OH− ions. Therefore, researching optimal DC values for casting significantly impacts electrochemical cell performance.
This thesis report focuses on fabrication, characterisation and performance evaluation of the cast membranes with DC empolyment, prepared from cationic polymer kindly provided from industrial collaborator. Furthermore, an attempt will be made to assess competitiveness between produced and commercially available membranes. Finally, future suggestions for research directions and alternative membrane fabrication techniques will be provided, as these could offer valuable insights for further exploration in this field.

... Read more

This work presents the design of the HAROLD, a partially wooden electric vertical take off and landing vehicle. The design covers the main aircraft subsystems, while also conceptually sizing a ground station to operate with the aircraft. ... Read more

In this study recyclable Twin Matrix Composites (TMC) have been developed and analysed. The reinforcements of these composites are pultrdued rods, which are made from carbon fiber and Bisphenol A Epoxy. These rods are embbed in a secondary matrix which is made from a bio-based epoxy resin and recyclamine curing agents.
This study focuses on the interlaminar properties of these TMCs and how they are impacted by recycling. The results indicate that the change in rod/secondary-matrix interface due to recycling is insignificant. This suggests that these TMCs can be considered as favourable condidates in for sustainable composite industries. ... Read more

Composite materials have revolutionized the world as we know it, but along the way, we have transformed that world, which is changing and suffering from global warming. This thesis explores the potential of bio-based resins for high-performance composite applications, focusing on a bio-based epoxy derived from brown algae, PHTE. The research investigates the feasibility of PHTE to replace BADGE epoxy, a bisphenol-A-based toxic and synthetic fossil-fuel-derived epoxy that comprises a major portion of aerospace composites. The study involved comprehensive material analysis and testing, including an examination of thermal, physical, and mechanical performance and a comparison of both systems. PHTE demonstrated excellent mechanical and thermal properties with high bio-based content, although its high viscosity posed challenges for traditional manual manufacturing techniques, especially composite manufacturing. The promising properties motivates to study and develop the recipe further for other high-performance applications as well apart from aerospace. ... Read more

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. ... Read more

This thesis explores the potential of sustainable resins in composite manufacturing, focusing on bio-based benzoxazine resins and bio-based epoxy derived from brown algae. The research investigates the feasibility of integrating these sustainable alternatives into composite structures. Bio-based benzoxazine resins were synthesized in-house, utilizing m-guaiacol, furfurylamine, sesamol, paraformaldehyde, Jeffamine T403, and DDS, while a commercial bio-based epoxy, phloroglucinol triepoxy (PHTE), was employed. The study involves comprehensive material analysis and testing, including an examination of chemical properties and mechanical performance. The findings reveal contrasting outcomes for the two types of bio-based resins. Bio-based benzoxazine resins exhibited challenges, as curing was not achieved, preventing their combination with composites. In contrast, phloroglucinol triepoxy, the bio-based epoxy from brown algae, emerged as a promising candidate for sustainable composite investigations. This resin demonstrated excellent mechanical properties, although its high viscosity and reactivity posed challenges for traditional manual manufacturing techniques. Furthermore, resin characterization unveiled a high glass transition temperature (Tg) system, especially noteworthy given the use of an aliphatic curing agent and monofunctional reactive diluent that lowers crosslinking density. This opens the door to its application in composites across various industries. ... Read more

In cold regions, the formation and accumulation of ice can cause safety hazards and impede proper operation of equipment. By example, ice accumulation on aircraft wings can increase drag, increase weight, reduce upward force and decrease aircraft speed.

For these reasons, proper anti- or de-icing techniques need to be developed. These techniques can be divided in passive and active systems. Active systems require a supply of external energy. On the other hand, by physical or chemical surface modification, passive systems inherently possess anti-/de-icing characteristics without the requirement of external energy. For this reason, this master thesis focuses on the development of passive anti-icing coatings.

One possible new approach to develop passive anti-icing coatings could be to modify surfaces with ice-binding proteins, more specifically anti-freeze proteins (AFPs). These proteins can be found in organisms living in cold climates. They are able to inhibit freezing, thus making life in cold environments possible. Currently, limited research has been performed regarding these AFPs as anti-icing coating material. As a result, this thesis delves deeper into the effect of different environments on the behaviour of AFPs. This is fundamental knowledge that needs to be uncovered before AFPs can be used as an anti-icing material.

In a first step, AFPs are directly attached to the surface in various concentrations using a polyethylene glycol (PEG) chain with a specific chain length. From the freezing data, an unexpected phenomenon was observed. It appears that AFP-surfaces freeze faster with increasing AFP concentration. As such, they act as ice promoter instead of the expected ice inhibitor. It is hypothesized that this phenomenon could be largely attributed to the limited protein mobility on the surface. To further test this theory, AFPs with various linker chain lengths were attached to the surface. Indeed, freezing was detected at later time points with increasing linker chain length meaning that AFPs with higher mobility are able to inhibit ice growth.

In addition, the incorporationof AFPs showed another interesting phenomenon as well. Ice dendrites on the AFP surfaces appeared to grow more straight compared to their silane-treated counterpart. Because of this, dendrites on the AFP-surfaces were also more easy to blow away.

Except for attaching AFPs directly to the surface, their behaviour within a polymeric environment is also studied. For this purpose, various concentrations of AFPs were incorporated within a PEG hydrogel. DSC was used to study the different types of water within the different AFP hydrogels. Interestingly, the amount of freezable bound water increased with increasing AFP concentration. No clear trend could be found between the amount of non-freezing water and the AFP concentration. In addition, freezing tests showed that hydrogels with increasing AFP concentration inhibited ice growth. This behaviour is opposite to the behaviour that was detected for AFPs attached directly to the surface.

In a final test, the hydrogels are dehydrated and again subjected to freezing tests. Now, the freezing behaviour follows a similar trend as the AFP-surfaces, meaning that, with increasing AFP concentration, ice formation is promoted.

From these results, it is clear that the environment of the AFPs plays a crucial role to the AFP behaviour. Depending on the type of environment in which they are introduced, AFPs can either act as ice inhibitor or ice promotor. ... Read more