Chitosan, which is a derivative of chitin, is particularly popular due to its biodegradable and renewable nature. However, the properties of chitosan can be inconsistent due to the extraction process and its natural origin, which poses a challenge to its use in composite materials as a matrix. The properties of chitosan can be tuned by controlling the degree of deacetylation (the extent to which acetyl groups are removed from chitin to form chitosan) and molecular weight. This paper presents a detailed study on the extraction and characterization of chitosan from shrimp shells. The structural thermal and mechanical characterization were studied using several techniques: Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The intrinsic viscosity and deacetylation degree were determined using various methods. The results showed an average degree of deacetylation of 77%. The chitosan films exhibited a high tensile strength of 43.9 MPa and an elongation at break of 3.14%. The thermal analysis revealed that the films had a glass transition temperature of 88 °C and a maximum thermal degradation temperature of 320 °C. The findings of this research could contribute to the development of chitosan-based materials with improved properties, leading to its wider adoption in the future for composite matrix application. The simple and efficient method used for the extraction and purification of chitosan from shrimp shells makes it a cost-effective and eco-friendly alternative to synthetic polymers.

Poly(lactide) (PLA) is an eco-friendly and low-cost polymer with a shear piezoelectricity easily induced by uniaxial stretching and without poling process. These interesting features make PLA as a good candidate to replace the widely-used poly(vinylidene difluoride) (PVDF) piezoelectric polymer, in particular for flexible energy harvesting applications aiming to power wearable sensors. In this work, PLA films were fabricated by a simple extrusion–orientation process. The energy harvesting efficiency of the PLA films were characterized using a custom-built test bench designed for flexible piezoelectric materials and working in tensile mode at low strain frequencies. The measurements on PLA films show a maximal output power about 3.7 μW harvested by applying a strain of 1% at 20 Hz. A theoretical model was developed based on electromechanical parameters to ascertain the energy harvesting performances of PLA. The validated model was also helpful to estimate the output power from PLA films by increasing their active surface areas and/or improving their shear piezoelectric coefficients (d ₁₄). The optimized PLA film could produce an output power comparable to that produced by PVDF film in the same mechanical excitation conditions. This study consequently highlights the potential of PLA for energy harvesting applications and the utility of the developed model to estimate the electrical power generated by piezoelectric polymers.

In this present work, we have successfully synthesized vertical aligned ZnO nanorod arrays (ZnO NRs) on conductive stainless-steel substrate. These ZnO NRs were obtained by using a low temperature, low cost, and eco-friendly hydrothermal approach. The effect of the sol-gel deposited ZnO seed layer on the vertical alignment ZnO NRs has been thoroughly studied. Characterizations of the seed layer and the as-obtained nanorods were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM), and water contact angles (WCA) measurement. SEM analysis shows that these nanorods were grown with a high uniformity and density over the entire substrate. TEM and XRD studies confirmed the hexagonal wurtzite structure of ZnO nanorods. Finally, field immersion tests using the optimized samples were conducted in a coastal sea environment to study biofouling settlement. To the best of our knowledge, there are few articles that investigate the influence of the seed layer deposited on stainless steel on the formation of vertically aligned nanorods for antifouling applications. The novelty of this work is manifested by optimizing the ZnO seed layer to obtain either thick or fine ZnO nanorods (NRs). Moreover, another novelty of this study is the use of the hydrothermal deposition of ZnO NRs on stainless steel for biofouling to replace paints in marine applications.

Additive manufacturing (AM) techniques are continuously evolving to meet the increasing demand for high-performance ceramics with intricate geometries. This review covers four widely investigated ceramic AM methods: stereolithography (SLA), digital light processing (DLP), fused deposition modeling (FDM), and direct ink writing (DIW). Each technique is analyzed from a technical standpoint, with particular attention given to feedstock formulation, printing parameters, debinding, sintering, and final densification. Vat photopolymerization provides high resolution and good surface quality, but remains constrained by photocurable slurry behavior. FDM offers accessible equipment and material versatility, though high ceramic loading can lead to feeding and printing difficulties. DIW can process highly loaded ceramic inks and is suitable for porous and architectured structures, but requires precise control of ink rheology and shape retention. The main challenges associated with ceramic printing are also examined, together with proposed solutions, emerging trends, and research gaps. This review provides a comparative overview of the critical parameters governing ceramic AM and helps identify the most suitable technique according to the targeted application.

La potentialité des films PLA produits par extrusion et étirés uniaxialement par MDO à partir des grades industriels a été investiguée pour la récupération d’énergie vibratoire par effet piézoélectrique. Une technique de caractérisation du coefficient piézoélectrique plus adaptée aux films polymères a été testée et validée sur un film piézoélectrique commercial de PVDF, puis utilisée pour évaluer le coefficient piézoélectrique d14 des films PLA. Une étude physico-chimique a été menée afin de comprendre les relations entre les observables piézoélectriques des films PLA et les modifications structurales (orientation moléculaire, cristallinité et nature des phases cristallines) apportées par les conditions d’élaboration des films. Un banc de test de récupération d’énergie reposant sur l’application des déformations de traction dynamiques a été utilisé pour évaluer la capacité des PLAs à convertir des vibrations mécaniques en énergie électrique. Une comparaison avec du PVDF commercial a été réalisée. Un modèle électro-mécanique équivalent a été développé et a permis de décrire l’évolution de la puissance électrique récupérée en fonction des conditions de sollicitations mécaniques pour différents grades de PLA ainsi que pour le PVDF. Ce modèle étant validé, a été utilisé pour prédire l’effet de la variation des différents paramètres intrinsèques (qualités mécaniques et piézoélectriques des polymères) et extrinsèques (conditions de sollicitations mécaniques et adaptation d’impédance électrique). Enfin, pour de futures applications, nous avons évalué la potentialité du PLA (sous forme de film ou de textile) pour des applications comme capteur de déformation, de force dynamique et de chocs mais aussi pour l’émission et la réception ultrasonore.