1,721,035 research outputs found
Accountability and Police Violence: a Research on Accounts to Cope with Excessive Use of Force in Italy
No full textAccountability is a vital element of policing. Over time, the public has demanded more control over police activities, while policing has attracted a good deal of controversy, such as the discriminatory and violent manner in which police officers treat individuals. In this paper, we explore Italian police accountability when faced with violent actions following the articulation at two levels: a micro-level — the communication strategies adopted by the police unions to account for their actions — and a macro-level — the understanding of the political and social system in which the police act, namely the Italian system. The results of the thematic analysis highlighted the recourse to excuses, justifications, and apologies. In terms of the effects on the audience, the unions divide into two groups: the first made exclusive use of defensive accountability strategies (excuses and justifications) and the second used reconciling accountability strategies (apologies). We discuss these findings regarding the interaction between the police and the public in Italy
Poly(butylene succinate) and poly(butylene succinate-co-adipate) for food packaging applications: Gas barrier properties after stressed treatments
No full textAliphatic polyester resins present the versatility of common plastics and are characterized by a good stability under ordinary conditions. They have acquired significant interest as environmentally friendly thermoplastics for a wide range of application, like food packaging field. We have investigated the permeability behavior of commercial poly(butylene succinate) (PBS) and poly(butylene succinate-co-adipate) (PBSA) polymers after food contact simulants and photo and thermal-oxidative degradation processes. Each stressed treatment was applied on thin film. Barrier properties to different gases (oxygen and carbon dioxide) were evaluated, showing that the chemical composition of the polymer strongly influenced the permeability to the gasses. Further, the same samples were tested at different temperatures, from 5 °C to 40 °C, in order to understand the effect of the temperature on the permeability behavior, and to calculate the process activation energy. Relations that bind the diffusion coefficients (D) and solubility (S) with temperature were studied. Differential Scanning Calorimetry (DSC) and FT-IR analyses were carried out in order to establish a correlation between permeability and sample structure/crystallinity. Negligible changes were evidenced in the polymers by means of DSC and FTIR measurements indicating structural stability of the polymers under process conditions. Gas barrier behavior, instead, resulted mainly affected by the process conditions, because mainly dependent on several chemical-physical factors. In both cases, no severe damage of the materials was observed
Poly(Neopentyl Glycol Furanoate): A Member of the Furan-Based Polyester Family with Smart Barrier Performances for Sustainable Food Packaging Applications
Full text linkIn the last decade, there has been an increased interest from the food packaging industry toward the development and application of bioplastics, to contribute to the sustainable economy and to reduce the huge environmental problem afflicting the planet. In the present work, we focus on a new furan-based polyester, poly(neopentyl glycol 2,5-furanoate) (PNF) to be used for sustainable food packaging applications. The aromatic polyester was successfully synthesized with high molecular weight, through a solvent-free process, starting directly from 2,5-furandicarboxylic acid. PNF was revealed to be a material with good thermal stability, characterized by a higher Tgand Tmand a lower RAF fraction compared to poly(propylene 2,5-furanoate) (PPF), ascribable to the two methyl side groups present in PNF glycol-sub-unit. PNF's mechanical characteristics, i.e., very high elastic modulus and brittle fracture, were found to be similar to those of PPF and PEF. Barrier properties to different gases, temperatures and relative humidity were evaluated. From the results obtained, PNF was showed to be a material with very smart barrier performances, significantly superior with respect to PEF's ones. Lastly, PNF's permeability behavior did not appreciably change after contact with food simulants, whereas it got worse with increasing RH, due to the polar nature of furan ring
Performance of Poly(lactic acid) Surface Modified Films for Food Packaging Application
Full text linkFive Poly(lactic acid) (PLA) film samples were analyzed to study the gas barrier behavior, thermal stability and mechanical performance for food packaging application. O2, CO2, N2, N2O, and C2H4pure gases; Air; and Modified Atmosphere (MA, 79% N2O/21% O2) were used to analyze the influence of the chemical structure, storage temperature and crystalline phase on the gas barrier behavior. The kinetic of the permeation process was investigated at different temperatures, ranging from 5°C to 40°C. Annealing thermal treatment on the samples led to the crystalline percentage, influencing especially the gas solubility process. Thermal properties such as Tgand Ïc, and mechanical properties such as tensile strength and modulus were remarkably improved with surface PLA modification. A more pronounced reinforcing effect was noted in the case of metallization, as well as improved gas barrier performance. Tensile testing and tensile cycling tests confirmed the rigidity of the films, with about a 20% loss of elasticity after 25 cycles loading
Quality- and sustainability-related issues associated with biopolymers for food packaging applications
No full textBiopolymers are increasingly gaining attention largely in response to the growing concerns about the sustainability of conventional polymers and the environmental pollution caused by plastic packaging waste treatment. In this regard, this chapter was designed to discuss, briefly but exhaustively, about the quality- and sustainability-related issues of biopolymers, thereby exploring their feasibility of usage for food packaging purposes. In particular, the attention was focused on poly(lactic acid) (PLA) as it is currently acknowledged to be one of the most versatile and widespread biopolymers: a review of its technical and environmental issues was performe
How Stress Treatments Influence the Performance of Biodegradable Poly(Butylene Succinate)-Based Copolymers with Thioether Linkages for Food Packaging Applications
Full text linkBiodegradable poly(butylene succinate) (PBS)-based random copolymers containing thioether linkages (P(BSxTDGSy)) of various compositions have been investigated and characterized from the gas barrier, thermal, and mechanical point of view, after food contact simulants or thermal and photoaging processes. Each stress treatment was performed on thin films and the results obtained have been compared to the same untreated film, used as a standard. Barrier properties with different gases (O2and CO2) were evaluated, showing that the polymer chemical composition strongly influenced the permeability behavior. The relationships between the diffusion coefficients (D) and solubility (S) with polymer composition were also investigated. The results highlighted a correlation between polymer chemical structure and treatment. Gas transmission rate (GTR) mainly depending on the performed treatment, as GTR increased with the increase of TDGS co-unit amount. Thermal and mechanical tests allowed for the recording of variations in the degree of crystallinity and in the tensile properties. An increase in the crystallinity degree was recorded after contact with simulant liquids and aging treatments, together with a molecular weight decrease, a slight enhancement of the elastic modulus and a decrement of the elongation at break, proportional to the TDGS co-unit content
Barrier properties of poly(propylene cyclohexanedicarboxylate) random eco-friendly copolyesters
Full text linkRandom copolymers of poly(propylene 1,4-cyclohexanedicarboxylate) containing different amounts of neopentyl glycol sub-unit were investigated from the gas barrier point of view at the standard temperature of analysis (23 °C) with respect to the three main gases used in food packaging field: N2, O2, and CO2. The effect of temperature was also evaluated, considering two temperatures close to the Tg sample (8 and 15 °C) and two above Tg (30 and 38 °C). Barrier performances were checked after food contact simulants and in different relative humidity (RH) environments obtained with two saturated saline solutions (Standard Atmosphere, 23 °C, 85% of RH, with saturated KCl solution; Tropical Climate, 38 °C, 90% RH, with saturated KNO3 solution). The results obtained were compared to those of untreated film, which was used as a reference. The relationships between the gas transmission rate, the diffusion coefficients, the solubility, and the copolymer composition were established. The results highlighted a correlation between barrier performance and copolymer composition and the applied treatment. In particular, copolymerization did not cause a worsening of the barrier properties, whereas the different treatments differently influenced the gas barrier behavior, depending on the chemical polymer structure. After treatment, Fourier transform infrared analysis confirmed the chemical stability of these copolymers. Films were transparent, with a light yellowish color, slightly more intense after all treatments
Reactive blending of poly(propylene 2,5-furandicarboxylate) and poly(propylene cyclohexanedicarboxylate). Bio-based multiblock copolymers for food packaging applications
No full textFuran-based polyesters loaded with nisin for sustainable antimicrobial packaging
No full textThis work focuses on the realization of fully bio-based blends from two different furan-based polyesters and natural preservatives, to obtain innovative/active food packaging. As preservative, nisin, a polycyclic antibacterial peptide produced by Lactococcus lactis, was mixed in 2.5 wt% amount, with the homopolymer poly(trimethylene furanoate), PTF, and the copolymer poly(butylene/pentamethylene furanoate), P(BPeF). The mechanical properties of the blends evidenced a modulation for flexibility and toughness, in particular in P(BPeF), owing to the presence of nisin, keeping at the same time the thermal stability, which is a key feature of these polyesters, as well as their thermal transitions.The evaluation of the functional properties highlighted the preservation of excellent gas barrier characteristics of PTF and P(BPeF). Lastly, the addition of nisin allows for the implementation of antibacterial features,absent in the pristine polymers, as the blends showed antimicrobial activity, by disc diffusion assay, against Lactiplantibacillus plantarum and Listeria monocytogenes. PTF containing 2.5% nisin were tested also in ACE juice, pH 4.5, inoculated with Listeria monocytogenes at 10^2 CFU/mL and stored at 4°C. L. monocytogenes growth was checked for 12d. After 8 d, it decreased under the detection limit in the sample with active packaging. In the control sample, the pathogenic species remained constant during the juice shelf-life
The Use of Polylactic Acid in Food Packaging
No full textPolylactide polymers have gained a great attention in the last decade to replace the conventional synthetic polymers and as a growing alternative packaging material for demanding food market.
Derived from renewable resources, polylactic acid is recognized as safe for use in contact food articles. Thanks to the modern and emerging production technologies; its cost is lowering, giving rise to the possibility of extending its use for packaging application for a broader variety of products. It is recyclable and compostable, and its physical and mechanical properties can be modulated through the polymer architecture
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