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.

An unprecedented rate of construction has profoundly increased the risk of scarcity of natural resources and threatened ecosystem sustainability. To establish an effective sustainable development policy, it is imperative to promote the use of responsible production channels, including waste recycling. Reuse of harbor dredged sediment is commonly investigated as a valuable alternative to non-renewable natural resources needed for construction. Sediment characterization is decisive in the valorization process, aiming to identify potential recycling paths. Existing research efforts, however, have rarely investigated case studies in developing countries. Moreover, they have tended to focus on the technical aspects, ignoring economic feasibility, which carries important implications. This paper fills this gap first by meticulously selecting laboratory tests for characterization within the means available in developing countries and second by conducting a cost-benefit analysis. The port of Safi, Morocco, was chosen for the implementation of the adopted approach. Results showed that dredged sediment is a sand readily reusable as a construction aggregate. Several applications are possible, the most interesting one being concrete works, as a substitute for conventional sand. While treatment by washing and dehydrating proved necessary, cost-benefit analysis confirmed the profitability of recycling. Hence, beneficial reuse of dredged sediment as construction material is technically and economically feasible.

The Lead Zirconate-titane(PZT) ceramic is known by its piezoelectric characteristic, but also by its stiffness. The use of a composite based on a polyurethane (PU) matrix charged by a piezoelectric material, enable to generate a large deformation of the material, therefore harvesting more energy. This new material will provide a competitive alternative and low cost manufacturing technology of autonomous systems (smart clothes, car seat, boat sail, flag …). A thin film of the PZT/PU composite was prepared using up to 80 vol. % of ceramic. Due to the dielectric nature of the PZT,inclusions of this one in a PU matrix raise the permittivity of the composite. For the most of industrial applications, the composite will not be used at room temperature, and as the energy harvested from this new materials have a direct relation with their permittivity we have made a study about the variation of the permittivity at different temperature and frequencies.

Electrostrictive polymers offer the promise of energy harvesting with few moving parts where power can be produced simply by stretching and contracting a relatively low-cost rubbery material. The use of such polymers for energy harvesting is a growing field, which has great potential from an energy density viewpoint. Basically, the relative energy gain depends on the current induced by the mechanical strain and frequency. A previous study in the Laboratoire de Génie Electrique et Ferroélectricité laboratory has indicated that one can measure the dielectric constant, the Young’s modulus, and the electrostrictive coefficient of a polymer film by determining the current flowing through the sample when the polymer film was simultaneously driven by an electrical field and mechanical excitation. The goal of this study has thus been to develop a solution for artificially increasing the coupling factor of electrostrictive materials, based on the optimization of the frequency of the electric field and the amplitude strain of the mechanical excitation leading to an increase in the generated current. When relating this parameter with a transverse strain of 5% and a bias field of 10 V/µm, it was found that such a process rendered it able to increase the converted power to 14 µW at a mechanical frequency of 6 Hz. The converted power was much higher than for the frequency of 3 Hz for which a low power was consumed by the polarization of the polymer. The theoretical analysis was supported by the experimental investigations. The contribution of this study provides a framework for developing energy harvesting techniques that should improve the overall performance of the system.

Investigated in this work, Cd_1−xZn_xSe-mixed ternary compounds were grown by the Bridgman method. Several compounds with zinc content varying in the range 0 < x < 1 were produced between two binary parents, CdSe and ZnSe crystals. Using the SEM/EDS technique, the accurate composition of formed crystals was determined along the growth axis. Thanks to that, the grown crystals’ axial and radial uniformity were determined. Characterization of the optical and thermal properties was undertaken. The energy gap was measured using photoluminescence spectroscopy for different compositions and temperatures. The bowing parameter describing the behavior of the fundamental gap with composition for this compound was found to be 0.416 ± 0.06. The thermal characteristics of grown Cd_1−xZn_xSe alloys were systematically studied. The thermal diffusivity and effusivity of the crystals under investigation were experimentally determined, allowing the calculation of the thermal conductivity. We applied the semi-empirical model that Sadao Adachi developed to analyze the results. Thanks to that, it was possible to estimate the contribution arising from chemical disorder to the crystal’s total resistivity.