Chen Wang

Known for superior mechanical properties, composite materials are widely chosen to produce lightweight structural components in aerospace applications. However, their high embodied carbon and resource-intensive waste treatment processes result in inherently high cradle-to-gate emissions for composite components. Repurposing in-process uncured prepreg from primary components fabrication to fabricate secondary aircraft components can potentially reduce the cradle-to-gate emissions of composite components and enhance material circularity by reducing the outflow of in-process waste and the inflow of prepreg required. To evaluate the environmental viability of prepreg repurposing, the life cycle assessment (LCA) was conducted on three secondary components designed for an electric vertical take-off and landing (eVTOL) aircraft, comparing the cradle-to-gate emission of components fabricated using virgin and repurposed carbon fibre epoxy prepreg. The results show a decrease in the cradle-to-gate emission of 5.60 kg CO2e, 4.89 kg CO2e, and 41.80 kg CO2e for L-brackets, access cover panel skins, and door panel skins, respectively, when fabricated from repurposed prepreg. A further analysis considering material circularity using the sustainability circularity score (SCS), found that each repurposing pathway represented by the fabrication of the respective components achieved a SCS at least twice that of the best performing recycling process, such as pyrolysis and solvolysis, indicating an overall greater circularity impact.

This study examined the effects of abrasive blasting and atmospheric-pressure plasma treatment on carbon-steel interfaces bonded with glass-fibre-reinforced epoxy and Elium resin matrices. Abrasive blasting produced a non-monotonic change in the apparent lap-shear strength: the highest surface roughness values of approximately 2, 4 and 6 μm gave the mean strengths of 17.5, 19.3 and 12.9 MPa, respectively, indicating that excessive roughness mitigated the adhesion benefits derived from mechanical interlocking. Plasma treatment significantly increased steel wettability, reducing the water contact angle from approximately 121.9° to below 10°, while X-ray photoelectron spectroscopy and Raman analyses revealed removal of carbonaceous contamination and formation of a cleaner, hematite-like oxide surface enriched with hydroxyl-related species. At the component level, surface treatment produced a matrix-dependent response. Abrasive blasting and plasma treatment increased the maximum bending moment of epoxy-based couplers by approximately 8% and 48%, respectively, whereas Elium-based couplers showed little change because the steel-Elium interface was no longer the limiting failure path. These results demonstrated that surface treatment was most effective when interfacial debonding controlled structural performance, and that matrix selection must be considered together with steel surface conditions when designing in-situ polymerisation of metal-composite pipe couplers.

Durable bonding across dissimilar material interfaces is essential for pipeline connections exposed to low temperatures, saline and corrosive environments, such as subsea and hydrogen transportation pipes. In this study, two cardanol-derived mussel-inspired curing agents with distinct diamine architectures were synthesised to regulate the low-temperature performance of epoxy interfaces between multiple materials commonly seen in pipeline systems, in terms of steel, Aluminium and PMMA. In the epoxy interfaces, flexible M1-EP contains a flexible aliphatic decamethylene spacer, whereas rigid M2-EP incorporates a relatively rigid aromatic m-xylylene unit. Comparable amine values allowed the influence of molecular architecture to be distinguished from differences in curing capacity. The DSC and DMA showed that flexible M1-EP possessed a lower glass-transition temperature of 72.50 °C compared with 81.23 °C for rigid M2-EP, indicating greater network mobility and stress-accommodation capability. The FTIR, XPS, SEM and EDS analyses revealed seawater-induced changes in N- and O-containing groups together with ion-enriched surface regions, supporting coordination and ion-dipole interactions between seawater-derived ions and the epoxy networks. Accordingly, both systems exhibited enhanced tensile and shear strength after curing in artificial seawater. At reduced temperatures, flexible M1-EP showed markedly better mechanical retention. Its tensile strength decreased by 21% from 20 to -40 °C, compared with 34% for rigid M2-EP, while its shear strength remained 14.56 MPa at -40 °C. M1-EP also exhibited stronger adhesion across aluminium, PTFE and PMMA substrates. After 50 freeze-thaw cycles, M1-EP retained a shear strength of 13.36 MPa compared with 10.53 MPa for M2-EP. The EIS further demonstrated slower interfacial degradation of M1-EP during prolonged cold seawater ageing and repeated freeze-thaw cycling. These results demonstrate that flexible diamine architecture effectively balances seawater-induced interfacial reinforcement with low-temperature stress accommodation, providing a molecular design strategy for durable epoxy bonding of heterogeneous interface in extreme environment for subsea couplers and hydrogen pipeline connections.

The short-fiber reinforced plastic made by injection molding have three-layer structure where two skin layers sandwich the core layer. The fiber direction on the skin layer of injection-molded plates is nearly along the molding flow direction (MFD), and that of the core layer is perpendicular. Three types of specimens loaded to parallel (MD), 45°(45°) and perpendicular (TD) to molding direction were fatigued. As a result, fatigue strength decreased in the order of MD, 45°, TD and the stiffness of the specimens decreased with stress cycles. Crack initiation and propagation life were estimated and the cause of the decrease in the stiffness was discussed.

Without using any environmentally hazardous organic solution, we fabricated hybrid solar cells (HSCs) based on the aqueous-solution-processed poly(3-hexylthiophene) (P3HT) dots and CdTe nanocrystals (NCs). As a novel aqueous donor material, the P3HT dots are prepared through a reprecipitation method and present an average diameter of 2.09 nm. When the P3HT dots are mixed with the aqueous CdTe NCs, the dependence of the device performance on the donor–acceptor ratio shows that the optimized ratio is 1:24. Specifically, the dependence of the device performance on the active-layer thermal annealing conditions is investigated. As a result, the optimized annealing temperature is 265 °C, and the incorporation of P3HT dots as donor materials successfully reduced the annealing time from 1 h to 10 min. In addition, the transmission electron microscopy and atomic force microscopy measurements demonstrate that the size of the CdTe NCs increased as the annealing time increased, and the annealing process facilitates the formation of a smoother interpenetrating network in the active layer. Therefore, charge separation and transport in the P3HT dots:CdTe NCs layer are more efficient. Eventually, the P3HT dots:CdTe NCs solar cells achieved 4.32% power conversion efficiency. The polymer dots and CdTe NCs based aqueous-solution-processed HSCs provide an effective way to avoid a long-time thermal annealing process of the P3HT dots:CdTe NCs layer and largely broaden the donor materials for aqueous HSCs.