Natural composite materials are gaining interest due to their low cost, recyclability, and availability. This study examines hemp-polypropylene (HPP) composites, where polypropylene (PP) is reinforced with 30 wt.% short hemp fibers (HF). The composites were produced via melt compounding using a twin-screw extruder, followed by injection molding. To improve adhesion between hydrophilic hemp fibers and the non-polar PP matrix, polypropylene-graft-maleic anhydride (PP-g-MA) was used as a coupling agent. Structural and mechanical properties were assessed using SEM, FTIR, tensile, and scratch tests. Results revealed a significant improvement in fiber-matrix adhesion with the use of PP-g-MA, demonstrating enhanced interfacial bonding. The hemp fibers were uniformly dispersed within the PP matrix, resulting in a dense and homogeneous composite structure. Mechanically, the addition of 30 wt.% HF markedly increased the stiffness and tensile properties of the composites. The Young’s modulus and tensile strength of the HPP composites reached 3804 MPa and 28.07 MPa, respectively, compared to 1523 MPa and 22.98 MPa for neat PP. Scratch testing further supported these findings, showing a notable reduction in penetration depth upon the inclusion of hemp fibers. This study highlights the potential of hemp-reinforced polypropylene composites as a sustainable alternative in applications requiring enhanced mechanical performance.

The present study attempted to synthesize ZnO nanoparticles (ZnO-NPs) and incorporate them into PMMA to fabricate a polymethylmethacrylate/Zinc Oxide Nano-particles (PMMA/ZnO-NPs) composite with concentrations of ZnO NPs of 1% wt, 2% wt and 3% wt for potential use in orthotic devices. The chemical composition, the microstructure and the morphology of the obtained composites were characterized using X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy. The mechanical properties and the antibacterial activity of the elaborated PMMA/ZnO-NPs were also determined. Results revealed that the optimum amount of ZnO NPs that would enhance the mechanical properties of the PMMA/ZnO NPs composite would be 2% wt. Indeed, this composite exhibited good mechanical properties. It showed a scratch toughness of 378.02 ± 18.1 MPa; a microhardness of 1.7 ± 0.09 MPa.m0.5, and a wear volume of about 2.47 ± 0.12106 μm3. This would indicate that there was an improvement of the same respective properties of PMMA by ∼ 41%, ∼42%, and ∼ 97%. In addition, this study revealed that the PMMA/ZnO NPs composite had excellent antimicrobial capacity against Escherichia coli (ATCC 25922) and Staphylococcus aureus ATCC 29213. The results showed that the PMMA/ZnO NPs at 2%wt composite could have encouraging implementations in the fabrication of orthotic devices.

Phase change materials (PCMs) are widely used for thermal energy storage; however, improving their thermal stability and minimizing supercooling effects remain important challenges. This study addresses these issues by synthesizing and characterizing new microencapsulated MCPs (microPCMs) that incorporate beeswax (BW), a sustainable biological source derived from animals, thus reducing the use of paraffins from petroleum resources, as the main material and calcium carbonate (CaCO₃) as the shell to improve overall performance. MicroPCMs with variable shell contents (20%, 40%, 60%, and 80%) were prepared and analyzed using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), particle size distribution analysis (PES), and differential scanning calorimetry (DSC) to evaluate their structural, morphological, and thermal properties. The results reveal that microPCMs exhibit a spherical morphology and robust core–envelope integrity, with thermal energy storage capacities ranging from 121.39 to 122.22 J/g, compared to 137.62 J/g for pure beeswax. In addition, the composites demonstrated reduced supercooling and stable thermal performance during repeated cyclic tests. This work introduces the use of calcium carbonate shells combined with a natural beeswax core to create environmentally friendly microPCMs with enhanced thermal stability and reduced supercooling, offering a sustainable alternative for efficient thermal energy storage.