1,720,993 research outputs found
Recent applications of biopolymers derived from fish industry waste in food packaging
No full textFish waste is attracting growing interest as a new raw material for biopolymer production in different application fields, mainly in food packaging, with significant economic and environmental advantages. This review paper summarizes the recent advances in the valorization of fish waste for the preparation of biopolymers for food packaging applications. The issues related to fishery industry waste and fish by-catch and the potential for re-using these by-products in a circular economy approach have been presented in detail. Then, all the biopolymer typologies derived from fish waste with potential applications in food packaging, such as muscle proteins, collagen, gelatin, chitin/chitosan, have been described. For each of them, the recent applications in food packaging, in the last five years, have been overviewed with an emphasis on smart packaging applications. Despite the huge industrial potential of fish industry by-products, most of the reviewed applications are still at lab-scale. Therefore, the technological challenges for a reliable exploitation and recovery of several potentially valuable molecules and the strategies to improve the barrier, mechanical and thermal performance of each kind of biopolymer have been analyzed
Fused Filament Fabrication and Computer Numerical Control Milling in Cultural Heritage Conservation
Full text linkThis paper reports a comparison between the advantages and disadvantages of fused filament fabrication (FFF) and computer numerical control (CNC) milling, when applied to a specific case of conservation of cultural heritage: the reproduction of four missing columns of a 17th-century tabernacle. To make the replica prototypes, European pine wood (the original material) was used for CNC milling, while polyethylene terephthalate glycol (PETG) was used for FFF printing. Neat materials were chemically and structurally characterized (FTIR, XRD, DSC, contact angle measurement, colorimetry, and bending tests) before and after artificial aging, in order to study their durability. The comparison showed that although both materials are subject to a decrease in crystallinity (an increase in amorphous bands in XRD diffractograms) and mechanical performance with aging, these characteristics are less evident in PETG (E = 1.13 +/- 0.01 GPa and sigma = 60.20 +/- 2.11 MPa after aging), which retains water repellent (ca = 95.96 +/- 5.56 degrees) and colorimetric ( increment E = 2.6) properties. Furthermore, the increase in flexural strain (%) in pine wood, from 3.71 +/- 0.03% to 4.11 +/- 0.02%, makes it not suitable for purpose. Both techniques were then used to produce the same column, showing that for this specific application CNC milling is quicker than FFF, but, at the same time, it is also much more expensive and produces a huge amount of waste material compared to FFF printing. Based on these results, it was assessed that FFF is more suitable for the replication of the specific column. For this reason, only the 3D-printed PETG column was used for the subsequent conservative restoration
Valorization of Food Industries Wastes for the Production of Poly(vinyl) Alcohol (PVA) Biodegradable Composites
No full textThis work is aimed to the development of new green composite materials by the incorporation of natural additives into poly(vinyl) alcohol (PVA). Two additives, shredded walnut shells and organic fraction of municipal solid waste (MW), were used to improve the mechanical properties of PVA. Both additives, derived from food industry wastes, were added in a PVA/water solution, which allowed to produce samples by the use of a pressure free process. Rheological analysis was performed in order to study the evolution of the material viscosity during thermal treatment, aimed at water removal. Samples obtained were characterized by means of differential scanning calorimetry (DSC), showing an improvement of the glass transition temperature brought by the addition of walnut shells. Finally, flexural tests were carried out on samples obtained after the incorporation of the different additives in PVA and compared with the mechanical properties of the neat matrix. Results obtained indicate the potential improvement brought by the addition of walnut shells, which allows increasing the flexural modulus of about 50%, at the expenses of a flexural strength reduction of about 30%. Also, at least for low amount of added water, the addition of MW was shown to provide an increase of the strain at break equal to 100%
Historically Accurate Reconstruction of the Materials and Conservation Technologies Used on the Facades of the Artistic Buildings in Lecce (Apulia, Italy)
Full text linkThe protection of the stone surfaces of the buildings of the city of Lecce (Apulia, Italy) represents an ancient practice, which has always allowed the conservation of the historical-artistic heritage of the city, which nowadays is an international touristic and cultural destination. The identification of ancient recipes, materials and methodologies for the protection of historical buildings plays an important role in establishing correct protocols in order to ensure the durability of stone surfaces over time. This work presents a historically accurate reconstruction of the materials and conservation technologies used on the facades of the artistic buildings in Lecce. Several historical buildings, both civil and religious, have been selected in order to investigate the treatments applied on their facades and to know the traditions spread in the past in the field of building conservation in the Salento territory. Thanks to non-invasive or micro-destructive techniques (optical microscopy, ATR-FTIR spectroscopy, pyrolysis–gas chromatography–mass spectrometry), the characteristic molecular markers of the materials and the products of degradation have been identified, deepening the knowledge of the mechanisms of deterioration and interaction between the stone material, the surface finish and the surrounding environment. The paper is a valuable tool for the knowledge of ancient traditions and the planning of proper restoration works
Efficient and environmentally friendly techniques for extracting lignin from lignocellulose biomass and subsequent uses: A review
Full text linkThe development of sustainable and effective methods for extracting lignin is crucial for achieving the advantages and promoting the shift towards a more sustainable and circular bioeconomy. This study addresses the use of environmentally friendly processes, including organosolv technique, supercritical fluid (SCF), non-thermal plasma (NTP), ionic liquids (ILs), deep eutectic solvents (DES), and microwave assisted extraction (MAE) techniques for lignin extraction. Organosolv treatment offers high selectivity and purity of lignin make this process economically feasible. Using supercritical water, carbon dioxide, or ethanol to extract lignin without harmful solvents is successful and customizable. NTP technologies break down lignin, simplifying processing and increasing its value. Whereas ILs may boost lignin synthesis and change its properties via solvent design. DES-based extraction methods can efficiently and specifically extract lignin. The rapid and effective MAE method employs microwave radiation to reduce extraction times and boost yields for lignin extraction. These methods feature high selectivity, little environmental impact, and the capacity to target lignin fractions. The study describes the fundamentals, benefits, and drawbacks of each extraction process, focusing on their ability to extract lignin on a large scale and its future usage. Additionally, this review explores the most recent advancements in the application sector, as well as the challenges and potential advantages of valorizing streams derived from extraction, thereby fostering the development of environmentally friendly and sustainable solutions. This research concludes that to overcome future challenges, need to address scale concerns, cost, emissions, and efficient lignin use
Biocompatible blends based on poly (Vinyl alcohol) and solid organic waste
No full textThis work is aimed at the development of new green composite materials through the incorporation of the solid organic waste (SOW) in a thermoplastic matrix. After being ground, the organic waste was exposed to a sterilization process, though an autoclave cycle, in order to obtain a complete removal of the bacterial activity. The SOW was found to have a high amount of water, about 65-70%, which made uneconomical its further treatment to reduce the water amount. Therefore, a water soluble polymer, poly (vinyl alcohol) (PVA) was chosen in order to produce SOW based blends. However, in order to reduce the viscosity of the PVA/SOW slurry, further amount of water was added. The very low viscosity attained by the water suspension allowed to process the PVA/SOW blends by a pressure-free process, for the production of samples, which were afterwards subjected to physical and mechanical characterization. Flexural tests showed the promising properties of the developed blends. In particular, the relevance of porosity was assessed. Increasing the water amount involved a signification increase of porosity, due to a faster water evaporation during processing. On the other hand, compared to neat PVA, addition of SOW allowed to significantly decrease the porosity of the produced samples. Despite this, the mechanical properties of the PVA/ SOW blends were shown to be lower than those of neat PVA processed analogously
Fully 3D-printed UHF RFID Antennas: Technological Comparison to Realize Conductive Elements
No full textIn this work, two promising Additive Manufacturing (AM)/3D-printing technologies, enable to realize conductive elements, are analysed, and compared with respect to the realisation of RFID applications. The selected techniques are the Fused Filament Fabrication (FFF) and Aerosol Jet® Printing (AJ® P), which have been compared, for the first time, by measuring the performance of an UHF RFID tag, specifically designed and realized for the scope. Results have also been analysed against to data obtained by a reference sample realized using the well-known technique of shaping an aluminium adhesive foil with a cutting plotter. While the resulting FFF-made tag can be read up to maximum 3 meters, the AJ® P one can be read up to 7 meters. Despite having major differences in terms of performance, this work demonstrates that both the technologies are capable to realize functional RFID prototypes
A Deep Investigation Into Nano SiO Reinforced RTV for High Voltage Insulators Application
No full textPreserving physical, mechanical, and electrical properties after UV irradiation is one of the essential functions of Room Temperature Vulcanized Silicone Rubber (RTVSIR) as an insulating coating. On high-voltage insulators exposed to flames brought on by lightning and sparks, flame retardant polymer coatings are essential. Utilizing flame retardant fillers is the typical way for enhancing the flame retardancy performance of polymeric materials. Current study investigates the effect of silica content (1, 3, and 5 wt.%) on various properties of RTV-SiO2 nanocomposite under accelerated weathering conditions. The relevant tests were performed according to the standards to study the mechanical properties such as hardness, maximum elongation, tensile strength, tear strength, density, and flame retardancy before and after aging. Results indicated that nano-silica presence in the silicon rubber polymer matrix could enhance its different properties as well as longevity. Hardness was raised by increasing the silica content and the rate of this enhancement changed even more after the ultraviolet (UV) irradiation. However, tear strength, tensile strength, and elongation at breakpoint showed the best result on the optimal value of silica (3 wt.%), and they were significantly reduced at higher percentages (5 wt.%). Water absorption percentage and flame retardancy also excessed with the increment of nano-silica in the composite. However, the optimal percentage of nano silica improves the quality of RTV while significantly reducing it at higher percentages
Coating's influence on wind erosion of porous stones used in the Cultural Heritage of Southern Italy: Surface characterisation and resistance
Full text linkWind erosion (or aeolian corrosion) is one of the most relevant causes of weathering and degradation which has affected building surfaces in Cultural Heritage. The effect depends on the wind strength, the impact of particles transported and their size and the characteristics of surfaces affected. This aspect is very important for historical buildings constructed by using limestone as Lecce stone (LS). LS has an extraordinary ability to be shaped, but is very sensitive to decay. Exfoliation, wind erosion, absorption of water by capillary from the soil, are its main degradation causes. For such a reason, the application of effective products able to act as “sacrifice film” became necessary in order to minimise the degradation rate by preserving the limestone substrate against serious weathering agents. In this work, the effects of aeolian corrosion, simulated by means the accelerated test with sandblasting method, were studied. In particular, the effectiveness of two specific commercial coatings, such as an innovative free-solvent hybrid organic-inorganic coating (HYBRID) and a solvent-based coating (AS), was assessed relating to their capability to preserve Lecce stone from the aeolian corrosion phenomenon. The protective efficacy was guaranteed by both the commercial coatings even after accelerated wind erosion test, by confirming a high hydrophobicity, low capillary water absorption and an adequate depth of penetration inside the stone able to assure durability
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