This study investigates hygrothermal durability of bio-epoxy composites reinforced with carbon, E-glass, basalt, and flax fibres. Fibre yarns and bio-composites were exposed for 3000 h at 60 °C and 98% relative humidity. The tensile strength reduction in the fibres and the interfacial shear strength (IFSS) reduction in the composites were assessed after ageing. Chemical deterioration was evaluated using energy-dispersive X-ray spectroscopy (EDS); morphological changes in fibres and composites fracture surfaces were examined using a scanning electron microscope (SEM). Results indicated that the durability was significantly influenced by fibre types. Tensile strength reduction was higher in carbon, glass and basalt compared to flax yarns because of chemical degradation of the sizing layer in synthetic fibres, while only physical damage was observed in flax. The IFSS reduction was highest in flax composites (10%), and lowest in carbon (4%). EDS indicated the hydrolysis and erosion of fibre sizing, with reduced silica content in glass and basalt fibres. SEM revealed matrix-dominated failure in carbon/bio-epoxy, interfacial debonding in glass and basalt composites, fibre slip and pull-out in flax/bio-epoxy. Overall, the results highlighted damage propagation pathways and demonstrated that bio-epoxy composites exhibited reasonable performance under hygrothermal ageing, supporting their potential as a sustainable alternative in durability-critical applications.

Conventional epoxy polymers and their composites are increasingly challenged by environmental concerns, high manufacturing costs, and limited recyclability, necessitating the exploration of sustainable alternatives. Many research groups have sought to develop alternate polymers from various renewable resources, such as lignin, polyphenols, natural resins, saccharides, and plant oils. This new type of polymer has led to the emergence of bio-based polymers, which are often used with different reinforcements as bio-based composites. In this review, the synthesis of different bio-epoxy resins is discussed in detail along with their chemical structures. Subsequently, the enhancements in the properties of these bio-composites with the addition of different nanomaterials such as carbonaceous nanofillers (carbon nanotubes, graphene nanoplatelets, graphene oxide, etc.), cellulose-based nanomaterials, inorganic nano-silica (spherical and mesoporous), and nano-clay is explained. Lastly, the properties of these bio-composites and their applications in civil engineering are highlighted. This review has provided a detailed overview of the developments in bio-composites that can be used as a guide for the development of a new class of bio-composites using other alternate resources.

Polypropylene (PP) mesh devices have been standard and successful implants for hernioplasty and are generally used to reinforce weak muscles of operated hernias due to their excellent properties of high strength, biocompatibility, and flexibility. Nevertheless, owing to their hydrophobic nature, PP mesh devices remain completely inert and make the prophylaxis of antibiotics ineffective after hernia repair. This review sheds light on the advances made in the way of surface modification aimed at developing infection-free PP mesh devices loaded with drug carriers and antibiotics. Different techniques have been employed to develop antimicrobial polypropylene mesh implants for sustained antimicrobial drug release. Surface functionalization with oxygen plasma treatment yielded excellent outcomes among various suggested surface modifications. The chitosan and β -cyclodextrin are the two most successful drug carriers functionalizing PP surfaces. The in vivo results suggest that the surface-modified antimicrobial PP meshes are significant value addition to future hernioplasty. The sustained in vivo studies and clinical trials could be the future work to assess the biocompatibility and durability of surface modified antimicrobial PP meshes.

This study investigates the low-velocity impact behaviour of Bouligand polymer composites in comparison with conventional three-dimensional (3D) composite architectures. Bouligand, bias, and orthogonal preforms were fabricated using carbon fibre filaments and subsequently infused with epoxy resin to produce laminated composite panels. Instrumented drop-weight impact tests were performed at energy levels of 10, 15, and 20 J to evaluate the load–displacement and load–time responses. These experimental results were complemented by finite element simulations to correlate the dynamic response and damage evolution. The analyses focused on impact-induced force histories, damage initiation, post-peak behaviour, and impact tolerance. The results show that Bouligand laminates exhibit distinctly different impact response mechanisms compared with conventional architectures. Although bias laminates sustained the highest peak loads at all impact energies, Bouligand laminates demonstrated prolonged contact duration (up to ∼6–8 ms longer at 15 J) and more pronounced post-peak load oscillations, indicative of progressive damage and enhanced energy dissipation. At 20 J, bias laminates experienced full penetration, whereas Bouligand laminates resisted perforation and exhibited global crack deflection with the smallest projected damage area among all architectures. Damage area increased approximately linearly with impact energy for all laminates; however, Bouligand structures consistently showed the lowest damage extent, while orthogonal laminates exhibited the largest damaged regions. Numerical predictions showed good agreement with experimental data, particularly at lower impact energies, confirming the reliability of the adopted modelling approach.