Fabrizio Sarasini

This work has investigated epoxy composites reinforced with wool fabrics modified by an organosolv lignin coating deposited via a sustainable protocol. The lignin layer was introduced to tailor the fiber/matrix interphase, aiming to improve adhesion and reduce water-related degradation associated with the intrinsic hygroscopicity of wool. Laminates were manufactured by vacuum-assisted resin transfer molding (VARTM) and systematically characterized. Thermogravimetric analysis demonstrated improved thermal stability and higher char yield in lignin-coated composites. Mechanical tests revealed enhanced flexural strength (+21%) and modulus (+31%), together with a modest increase in interlaminar shear strength. SEM analysis of the fracture surfaces provided additional evidence of changes in fiber–matrix interfacial interactions. Low-velocity impact and DMA results further supported the role of the coating in improving load transfer and viscoelastic response. Water absorption tests indicated reduced equilibrium uptake and slower diffusion kinetics, highlighting the hydrophobic barrier function of the lignin layer. Collectively, these results show that the lignin coating acts primarily as an interphase modifier and water-barrier layer, enabling low-value wool fabrics to be upgraded into functional reinforcements for more durable epoxy biocomposites.

Modern engineering, driven by the need to reduce CO2 emissions and improve energy efficiency, is increasingly turning toward the use of advanced composite structures, particularly sandwich material...

We report a quantum energy truncation terahertz coherence tomography technique that enables highly localized extraction of molecular-species-specific THz responses. The method exploits resonant photon loss when the emitter THz energy matches molecular vibration quanta. Reflected THz radiation is recorded and mapped into depth-coded image sequences, from which subsurface structural information and molecular fingerprints are retrieved to construct three-dimensional tomograms. This approach resolves major limitations of conventional continuous-wave (CW) THz imaging-namely, its lack of spectroscopic specificity and dependence on angular scanning-by directly correlating molecular excitation spectra with depth information. As a result, quantum energy truncation terahertz coherence tomography enables rapid, three-dimensional THz imaging with selective sensitivity to discrete molecular quantum energy transitions, providing new opportunities for nondestructive characterization of material refractive indices, molecular composition, and subsurface structures.

This paper investigates the valorization of peanut shell powder (PSP), an abundant agro-industrial residue, as a biofiller for the development of sustainable 3D printable PLA-based composites for food packaging applications. A low-filled biocomposite containing 2.5 wt.% PSP was successfully processed into filament with dimensional tolerances suitable for fused deposition modeling printing. Thermal and melt flow analyses demonstrated that PSP marginally reduced the thermal stability of PLA while preserving its thermal transition temperatures and increasing the melt flow rate up to 51%. Differential scanning calorimetry revealed a slight increase in crystallinity in biocomposite filament compared to neat PLA pellets, mainly associated with thermo-mechanical processing of the extrusion, while the lower crystallinity degree relative to PLA extrudate suggested a negligible nucleating effect of PSP. To optimize print quality, different extrusion temperatures and infill flow rates were evaluated. The best mechanical performance was achieved at 200 °C and 130% flow rate, where reduced inter-filament porosity (5.2%) resulted in improved tensile strength and stiffness compared with the other printing conditions. Although mechanical properties remained lower than neat PLA, the material proved suitable for non-structural packaging applications. Prototype packaging boxes were fabricated and tested for the storage of fresh-cut melon. Compared with neat PLA packaging, the PLA-PSP system better preserved fruit firmness over 10 days, inhibited fungal growth, and delayed visible deterioration, highlighting the potential active role of PSP in food preservation. Anaerobic biodegradation tests conducted under mesophilic conditions confirmed that the addition of PSP did not hinder PLA biodegradability and slightly enhanced methane production. Overall, the results demonstrate that peanut shell waste can be effectively upcycled into functional 3D-printable biocomposites for sustainable packaging solutions.

Photothermal methods for measuring thermal diffusivity inherently involve an ill-posed inverse problem influenced by multiple factors, including sample thickness, heating or cooling duration, and excitation energy. Measurement accuracy becomes particularly challenging under non-impulsive pulsed excitation when the observation timescale is comparable to the pulse duration. This difficulty arises from poorly defined pulse profiles, broadened thermal responses, and the lack of clear boundary condition criteria - especially under significant interfacial temperature gradients where natural convection dominates (Grashof number Gr >> 2,000). Although the classic Parker solution is widely used, it is physically unrealistic because it assumes adiabatic heat flux and shallow-region heat absorption. In this study, we demonstrate that Parker’s assumption is mathematically equivalent to a Dirac pulse boundary condition. We then derive comprehensive analytical solutions for both thermal and cooling responses under Dirac and rectangular pulse excitations. By comparing these with eigenfunction-based solutions under well-posed boundary conditions, we reveal that Parker’s model is valid only before the thermal peak occurs. Through dimensionless analysis, we further show that Parker’s solution represents the limiting case of the rectangular pulse model as the heating duration approaches zero. Finally, we propose a novel excitation approach—evaporative cryocooling—for thermal diffusivity measurements. This technique provides a compact, low-cost, and easily implemented alternative to conventional excitation schemes. The theoretical model is further validated through comparison with experimental results.