This study explores the development of sustainable bamboo fiber-reinforced bio-based polycarbonate (BF-PC) composites. Prepreg laminates were fabricated using solvent-based impregnation and compression molding. The effects of chemical surface modifications—alkali and silane—on bamboo fiber properties, interfacial bonding, and composite performance are studied and supplemented by comprehensive characterization, including FTIR, SEM, fiber density, single fiber tensile testing, cross-sectional microscopy, void fraction analysis, and tensile and flexural testing. Results revealed that 2 g/L silane-treated fibers showed the highest improvements in mechanical properties and interfacial adhesion, achieving tensile and flexural strengths of 162 MPa and 184 MPa, respectively. In contrast, alkali treatments failed to improve bonding and resulted in lower composite performance. In summary, surface chemistry of natural fibers and circular buildings, circular composites, natural fibre composites, renewable composites, renewable matrixcomposite processing play a crucial role in renewable polycarbonate matrix composite engineering.

The drawback of biobased polymer matrix composites (PMCs) is their limited temperature stability, resulting from degradation, which restricts their processability in established composite manufacturing processes requiring elevated temperatures. These key issues not only affect the mechanical properties but ultimately limit the utilization of flax fibers as fiber reinforcement in PMCs. In this study, kinetic models for the thermal degradation of flax fibers and PA11 are derived and combined with a model for thermo-chemical fiber degradation. Selective degradation of the fibers and mechanical testing establishes a link between degradation and the accompanying deterioration of the mechanical performance. The deterioration of flax fiber mechanical properties under concurrent thermal and thermo-chemical degradation is primarily governed by the thermos-chemical contribution (chain scission) up to 3% thermal degradation, beyond which the influence of thermal degradation becomes evident. Even 1% thermal degradation of flax fibers results in a pronounced reduction in their mechanical performance. In contrast, equal degradation values enhance the PMCs' strength, which may be attributed to improved fiber-matrix interactions. Compiling results into processing maps establishes a framework for designing tailored processing of temperature-sensitive materials, offering transfer opportunities to individual processing conditions and heat treatments, enabling broader research on bio-based PMCs.

Sustainable polymers are essential to reducing the environmental impact of conventional plastics. While the use of renewable feedstocks plays a significant role, the adoption of green processes, including sustainable solvent selection and efficient polymer purification, is equally essential. This study presents a green synthesis route for polymers based on two renewable vinyl lactone monomers: α-methylene-γ-valerolactone (MeGVL) and α-methylene-γ-butyrolactone (MeGBL). Polymerization was performed in renewable solvents as Cyrene®, γ-valerolactone, and 2-methyltetrahydrofuran via solution and in biobased alcohols through precipitation methods. While solution polymerization requires additional purification step through polymer precipitation, precipitation polymerization enables efficient polymer recovery and solvent reuse. The resulting polymers made via precipitation polymerization exhibit properties with glass transition temperatures of 99 °C (polyMeGVL) and 94 °C (polyMeGBL), and visible light transmittance over 96% between 450-700 nm of both polymer films of thickness around 100 μm. Water contact angles of the films were 62° for polyMeGVL and 51° for polyMeGBL showing difference despite having a similar chemical composition. These results highlight a scalable, low-impact pathway for producing commodity polymers entirely from renewable resources.

Utilization of sustainable feedstocks to fabricate renewable thermosetting epoxy resins has been of great interest recently; however, their translation into composite structures and benchmark comparisons are poorly understood. Phloroglucinol is a phenolic molecule obtained from brown algae, and its epoxidized form is a high viscosity, high reactivity monomer. In this study, the potential of epoxidized phloroglucinol as a laminating resin was examined in comparison with a bisphenol A diglycidyl ether (BADGE) epoxy monomer employing the Epikure 04908 linear amine hardener system. Utilization of a reactive diluent for PHTE resin was necessary for room temperature laminating applications to reduce viscosity, and the thermomechanical properties of PHTE-based resins and composites are superior to those of BADGE systems.

With Mars colonisation becoming a reality for the near future, it is of importance to analyse how crew and cargo can be transported between Earth and a colony on Mars. This article is a feasibility and design study of a launch vehicle whose mission is to shuttle crew and cargo from Low Mars Orbit to a colony on the Martian surface. A single-stage reusable rocket has been selected to fulfil this mission, code-named Charon. The mission profile of such a vehicle was created, leading to a Maximum Growth Allowance (MGA) Delta-V budget of 6.2 km/s. With the mission profile in mind, each subsystem underwent a preliminary design. With reliability and maintainability in mind, subsystems were designed for redundancy and modularity, and an abort system was included for an added level of safety. The iterative design process resulted in a vehicle with a MGA mass of 198.7 tons, capable of transporting 1200 kg of cargo and a crew of 6 people to a 500 km orbit and back. The preliminary design of the vehicle is deemed safe. Following a fault tree analysis, the Single Launch Loss of Mission, Vehicle and Crew (SL-LOM, SL-LOV, SL-LOC) probabilities are computed to be of 0.975%, 0.12%, and 0.079%. Finally, from the vehicle’s constraints on the base, the feasibility of the project has been reflected upon. It is deemed that such a concept is of high interest only when the base is already operational, due to the launch and maintenance infrastructure that it requires, as well as the power it requires from the Martian base.