88 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
The aspect ratio of epoxy matrix nanocomposites reinforced with graphene stacks
No full textThe improvement of physical and mechanical properties
of nanofilled matrices significantly depends on the
average size of dispersed fillers. In particular, the aspect
ratio of lamellar nanofillers, such as graphene
stacks, results from a combination of both filler morphology
and processing techniques. In this study,
nanocomposites were obtained dispersing three different
graphene precursors in an epoxy resin: expanded
graphite, commercial graphene nanoplatelets, and natural
graphite. Epoxy matrix nanocomposites reinforced
with graphene stacks, ranging from 1 wt% to 3 wt%
were prepared and characterized. The structural, mechanical,
and thermal properties of expanded graphitebased
nanocomposites, as well as the rheological
properties of liquid resin/filler suspensions, were studied
and compared with those of the unfilled epoxy matrix
and of the matrix filled with natural graphite and
commercial nanoplatelets. The comparison of mechanical
and rheological properties with simple mathematical
models indicated that the aspect ratio of expanded
graphite is in the order of 1000, i.e., a dispersion of
nanoscale graphene stacks was obtained. This result
suggests that the measurement of engineering properties
of nanocomposites not only represents an objective
but can also provide information about the average
degree of dispersion
Studio del meccanismo di formazione della miscela in un motore 2T iniezione diretta ad accensione comandata
No full textStudio del meccanismo di formazione della miscela in un motore 2T iniezione diretta ad accensione comandata
No full textCold-Curing Structural Epoxy Resins: Analysis of the Curing Reaction as a Function of Curing Time and Thickness
No full textThe curing reaction of a commercial cold-curing structural epoxy resin, specifically formulated for civil engineering applications, was analyzed by thermal analysis as a function of the curing time and the sample thickness. Original and remarkable results regarding the effects of curing time on the glass transition temperature and on the residual heat of reaction of the cold-cured epoxy were obtained. The influence of the sample thickness on the curing reaction of the cold-cured resin was also deeply investigated. A highly exothermal reaction, based on a self-activated frontal polymerization reaction, was supposed and verified trough a suitable temperature signal acquisition system, specifically realized for this measurement. This is one of the first studies carried out on the curing behavior of these peculiar cold-cured epoxy resins as a function of curing time and thickness
Modelling the Mixture Formation in a Small Direct-Injected Two-Stroke Spark-Ignition Engine
No full textComputations were carried out to simulate in-cylinder flow field and mixture preparation of a small port scavenged direct-injection two-stroke spark-ignition engine using a modified version of KIVA-3 code. Simulations of the interaction between air flow and fuel were performed on a commercial Piaggio (125 cc) motorcycle engine modified to operate with a hollow-cone injector located in different positions of the dome-shaped combustion chamber. The engine has a large exhaust port and five smaller transfer ports connecting the cylinder to the crankcase. The numerical grid of this complex geometry was obtained using an IBM grid generator based on the output of engine design by CATIA solution. To take into account the rapid distortion of flow, the standard k-ε turbulence model in KIVA-3 was replaced by the RNG k-ε model.
Three cases of hollow-cone injector locations were explored: one, located on the head, injected the fuel along the cylinder axis; another one, also located on the head, injected the fuel in counter flow; the third one, located on cylinder wall, injected the fuel towards the combustion chamber.
It was found that the most important parameters that strongly influence in-cylinder droplet vaporization process and spatial vapor distribution are: fluid flow pattern, injector location, injection pressure and injection timing
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
Fused Filament Fabrication and Computer Numerical Control Milling in Cultural Heritage Conservation
No full textThis 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%
Modeling the Mixture Formation in a small Direct-Injected Two-Stroke Spark Ignition Engine
No full text- …
