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All -PLA blends have been fabricated by an easily scalable and green melt-blending of linear-PLLA and 3-armed star-shaped PDLLA at different proportions (100:0, 95:5, 90:10, 80:20, and 50:50, w:w). The fabrication process, carried out in a hot-press, consisted of three steps: an initial heating of the thoroughly blended polymer mixtures at 170 °C for 5 min, a second heating at 170 °C for 5 min with a pressure of 200 Pa, and a final cooling at room temperature during 20 min keeping the same pressure. This methodology resulted in very homogenous amorphous samples, as revealed by XRD and DSC. The incorporation of star-PDLLA toughened the polylactide matrix by a clear ductilization, opening opportunities for the expanded use of the developed blends in different applications, due to their increased processability. DSC analysis revealed indeed that by increasing star-PDLLA content it is possible to gradually reduce the T g , as well as the capability of crystallization of the linear-PLLA component. Such properties determine a plasticizing effect on the final blends. The increased content of the star component turned the films from transparent to translucent and decreases the thermal decomposition temperatures, which remain in any case very well above room temperature. The water vapor transmission rates varied with the star-PDLLA content between values characteristic for isolating to breathable films, thus allowing the use of these blends in different applications such as food packaging and biomedical devices. Finally, no important changes of water contact angle and water uptake were observed between the different blends. Despite the negligible effect of seawater on the biodegradation of commercial PLA, star-PDLLA-containing blends showed high biodegradation rates at short-times in marine environments, reinforcing the environmentally friendly character of polylactide. Image 1 • All -PLA blends have been fabricated by melt-blending of linear and star PLA. • The incorporation of star PLA toughened the polylactide matrix. • These blends showed high biodegradation rates at short-times in marine environments. [ABSTRACT FROM AUTHOR]

Metals used for food canning such as aluminum (Al), chromium-coated tin-free steel (TFS) and electrochemically tin-plated steel (ETP) were coated with a 2–3-µm-thick layer of polyaleuritate, the polyester resulting from the self-esterification of naturally-occurring 9,10,16-trihydroxyhexadecanoic (aleuritic) acid. The kinetic of the esterification was studied by FTIR spectroscopy; additionally, the catalytic activity of the surface layer of chromium oxide on TFS and, in particular, of tin oxide on ETP, was established. The texture, gloss and wettability of coatings were characterized by AFM, UV-Vis total reflectance and static water contact angle (WCA) measurements. The resistance of the coatings to solvents was also determined and related to the fraction of unreacted polyhydroxyacid. The occurrence of an oxidative diol cleavage reaction upon preparation in air induced a structural modification of the polyaleuritate layer and conferred upon it thermal stability and resistance to solvents. The promoting effect of the tin oxide layer in such an oxidative cleavage process fosters the potential of this methodology for the design of effective long-chain polyhydroxyester coatings on ETP. [ABSTRACT FROM AUTHOR]

A mixture of trifluoroacetic acid:trifluoroacetic anhydride (TFA:TFAA) was used to dissolve chitin from shrimp shells. Free-standing films were prepared by blending the chitin solution and glycerol at different percentages, followed by drop-casting, and the complete evaporation of the solvents. After this process, the chitin matrix showed an amorphous molecular structure, as determined by X-ray diffraction. Optical, mechanical, thermal, and antioxidant properties were also thoroughly investigated. The incorporation of glycerol induced a plasticizing effect on the mechanical response of films and improved their transparency. In addition, hydrodynamic and barrier properties were determined by contact angle and water vapor/oxygen transmission rates, respectively, and revealed typical values of other polysaccharides. These bioplastics also presented an excellent greaseproof behavior with the highest degree of oil repellency as determined by the Kit test. Moreover, the overall migration was evaluated by using Tenax® as a dry food simulant and levels were compliant with European regulations. Their antifungal properties were tested using Botrytis cinerea as a model. Biodegradability was also determined by measuring the biological oxygen demand in seawater. Degradation rates were high and similar to those of other fully-degradable materials. [Display omitted] • TFA:TFAA solvent mixture was used to dissolve chitin. • Chitin structure was amorphous after the evaporation of the solvents. • The use of glycerol as a plasticizer controls the mechanical properties. • Chitin-glycerol bioplastics are transparent, grease resistant, and biodegradable. [ABSTRACT FROM AUTHOR]

Bio-based lacquers prepared from an underutilized tomato processing residue such as pomace have been investigated as sustainable alternatives to bisphenol A (BPA)-based coatings for metal food packaging. The fabrication methodology consisted of a two-step process: spray-coating of a paste of the lipid fraction of tomato pomace with a mixture ethanol:H 2 O (3:1, v:v) on common metal substrates, used for food canning, such as aluminum (Al), chromium-coated tin-free steel (TFS), and electrochemically tin-plated steel (ETP), followed by the self melt-polycondensation of such lipid fraction. The polymerization reaction was conducted at 200 °C for different times (10, 20, 30, 40, 50, and 60 min) and was monitored by specular infrared spectroscopy, resulting in maximum degrees of esterification of ∼92% for Al and ∼85% for TFS and ETP substrates. The anticorrosion performance of the coatings was studied by electrochemical impedance spectroscopy at different immersion times (time intervals of 2–5 h during an overall stability test up to 170 h) in an aqueous solution of 1 wt% NaCl. The degree of polymerization and the physical properties of the coatings showed a strong dependence on the metal substrate used. In general, the best results were found for tomato pomace-based lacquers applied on aluminum, achieving higher mechanical strength (critical load of 1739 ± 198 mN for Al, 1078 ± 31 mN for ETP, and 852 ± 206 mN for TFS), hydrophobicity (water contact angle ∼95° for Al, ∼91° for ETP, and ∼88° for TFS), and improved anticorrosion performance (coating resistance of 0.7 MΩcm2 after 170 h of immersion for Al, 0.7 MΩcm2 after 70 h of immersion for TFS, and negligible coating resistance for ETP). In view of the technical innovation proposed in the present paper, the estimation of the environmental sustainability of the process has been considered relevant to fit the circular economy target. For this purpose, a life cycle analysis (LCA) was applied to the overall process, revealing multiple advantages for both the environment and human health. [Display omitted] • Tomato pomace is used to fabricate lacquers for metal packaging. • A degree of esterification of ∼92% was achieved for the coating on aluminum. • These bio-based lacquers show good anti-corrosion properties. • A coating resistance of 0.7 MΩcm2 after 170 h of immersion was determined for Al. • The overall fabrication process is sustainable as evaluated by life cycle analysis. [ABSTRACT FROM AUTHOR]