Luigi Torre’s research while affiliated with University of Perugia and other places

The increasing environmental pollution resulting from plastic waste and the need to reuse agro-industrial wastes as a source of discarding has led to the development of innovative biobased products. In the frame of this context, the use of neat polylactic acid (PLA) and its blend with polybutylene succinate (PBS) with or without cellulose nanocrystals (CNCs) extracted from hemp fibers is explored here. This study aimed to assess the biogas production of different biopolymeric films. In parallel, life cycle assessment (LCA) analysis was performed on the same films, focusing on their production phase and potential end-of-life scenarios, regardless of film durability (i.e., single-use packaging) and barrier performance, to counteract possible soil health threats. Specifically, this study considered three specific systems: PLA, PLA_PBS (PLA/PBS blend 80:20 w/w), and PLA_PBS_3CNC (PLA/PBS blend + 3% CNCs) films. The assessment involved a batch anaerobic digestion (AD) process at 52 °C, using digestate obtained from the anaerobic treatment of municipal waste as the inoculum and cellulose as a reference material. The AD process was monitored over about 30 days, revealing that reactors containing cellulose showed inherent biodegradability and enhanced biogas production. On the other hand, biopolymeric films based on PLA and its blends with PBS and CNCs exhibited an inhibitory effect, likely due to their recalcitrant nature, which can limit or delay microbial activity toward biomass degradation and methanogenesis. LCA analysis was performed taking into consideration the complex environmental implications of both including biopolymers in the production of renewable energy and the use of post-composting digestate as an organic fertilizer. Remarkably, the PLA_PBS_3CNC formulation revealed slightly superior performance in terms of biodegradability and biogas production, mainly correlated to the presence of CNCs in the blend. The observed enhanced biodegradability and biogas yield, coupled with the reduced environmental impact, confirm the key role of optimized biopolymeric formulations in mitigating inhibitory effects on AD processes while maximizing, at the same time, the utilization of naturally derived energy sources.

Using biomass to develop and obtain environmentally friendly and industrially applicable biomaterials is increasingly attracting global interest. Herein, cellulose nanocrystals (CNCs) and lignin nanoparticles (LNPs) were extracted from Lemna minor L., a freshwater free-floating aquatic species commonly called duckweed. To obtain CNCs and LNPs, two different procedures and biomass treatment processes based on bleaching or on the use of an ionic liquid composed of triethylammonium and sulfuric acid ([TEA][HSO4]), followed by acid hydrolysis, were carried out. Then, the effects of these treatments in terms of the thermal, morphological, and chemical properties of the CNCs and LNPs were assessed. The resulting nanostructured materials were characterized by using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that the two methodologies applied resulted in both CNCs and LNPs. However, the bleaching-based treatment produced CNCs with a rod-like shape, length of 100–300 nm and width in the range of 10–30 nm, and higher purity than those obtained with ILs that were spherical in shape. In contrast, regarding lignin, IL made it possible to obtain spherical nanoparticles, as in the case of the other treatment, but they were characterized by higher purity and thermal stability. In conclusion, this research highlights the possibility of obtaining nanostructured biopolymers from an invasive aquatic species that is largely available in nature and how it is possible, by modifying experimental procedures, to obtain nanomaterials with different morphological, purity, and thermal resistance characteristics.

The influence of a highly complex modified commercial rosin resin (Unik Print, UP) on the thermomechanical performance of four commercial grades of polylactic acid (PLA) has been evaluated and compared. Comparative experiments were carried out with polylactides of different molecular weights and phase structures. The melt-extruded formulations were prepared by considering 3 parts per hundred resins (phr) of modified rosin resin, which was previously verified to be the suitable amount of UP resin effective to enhance PLA performance. Several analytical characterization techniques were used for comparison purposes. Among them, the thermogravimetric analysis allowed to determine that UP resin does not influence PLA's thermal decomposition behavior, regardless of PLA molecular weight and crystallinity degree. Differential Scanning Calorimetric (DSC) evaluation showed that UP resin eliminated both exothermal and endothermic peaks of amorphous PLA. At the same time, it was proved that the formation and growth of different types of crystal can be promoted in semi-crystalline PLA. Moreover, a toughness improvement was observed in all formulations. Besides, the rotational rheometer allowed to measure the viscosity of the final materials, finding that in amorphous PLA with low molecular weight, the UP resin did not cause apparent changes. However, the complex viscosity was increased for both semi-crystalline PLA (low and high molecular weight).

Carbon/Phenolic Composites (CPCs) are essential to manufacture many portions of the nozzle assembly of Solid Rocket Motors (SRMs) which are essential both to preserve the independent access to space as well as for the homeland security. In our research, a feasible approach aimed at preliminary retrieving the in-plane and out-plane thermal diffusivity of CPCs through the Oxy-Acetylene Torch (OAT) tests was validated. The proposed approach showed to be effective and able to bypass some limitations of common protocols, especially in terms of capability to determine the thermal diffusivity of CPCs at high heating rates. A comprehensive work of comparison of the obtained data with state-of-the-art CPCs such as MX-4926 and FM-5014 has also been carried out, evidencing the effectiveness of the proposed method.

Physics research is constantly pursuing more efficient silicon detectors, often trying to develop complex and optimized geometries, thus leading to non-trivial engineering challenges. Although critical for this optimization, silicon tiles' mechanical data are hardly present in the literature. In an attempt to partially fill this gap, the present work details various mechanical-related aspects of spaceborne silicon detectors. Specifically, the study concerns three experimental campaigns with different objectives: a mechanical characterization of the material constituting the detector (in terms of density, elastic, and failure properties), an analysis of the adhesive effect on the loads, and a wirebonds vibrational endurance campaign performed on three different un-potted samples. By collecting and discussing the experimental results, this work aims to fulfill its purpose of providing insight into the mechanical problem associated with this specific application and procuring input data of paramount importance. For the study to be complete the perspective is broader than the mere silicon analysis and embraces all the related aspects i.e. the detector-structure adhesive interface and the structural integrity of wirebonds. In summary, the paper presents experimental data on the material properties of silicon detectors, the impact of the adhesive on the gluing stiffness, and un-potted wirebonds' vibrational endurance. At the same time, the discussion of the results furnishes an all-encompassing view of the design-associated criticalities in experiments where silicon detectors are employed.