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In this work, different food‐contact experimental and commercial aqueous polymeric dispersions were applied to paperboard via rod coating technology to achieve <5% non‐cellulosic content. Barrier (water, moisture and grease), mechanical (tensile and bending) and converting (heat‐sealing and creasing) properties were analysed before tray formation trials on pilot‐scale equipment. Dispersion‐coated samples were compared against polyethylene terephthalate (PET) extrusion‐coated paperboard, the principal industrial material used for food trays. Results show that, within the investigated properties, waterborne dispersions can achieve similar barrier properties compared with PET, yet at lower dry coat grammage (12 g/m2 vs. 40 g/m2 of PET‐coated paperboard). Additionally, the investigated coatings heat‐sealed at temperatures as low as 80–90°C, almost 100°C less than PET; however, lower seal forces could be achieved (15–20 N/(25 mm) vs. 23 N/(25 mm) of PET‐coated paperboard). Paperboard delamination occurred at the highest seal forces. Dispersion‐coated trays were obtained at 4.5–5.0% blank moisture content. Formed trays at industrial processing parameters showed critical coating damage during converting due to tensile stresses. This work shows that milder processing conditions allow a reduction in coat defects. [ABSTRACT FROM AUTHOR]

Packaging waste correct sorting hugely impacts fiber-based packaging circularity. Currently, this is more crucial than ever, also due to the increased market share of fiber-based packaging. This study evaluated the relationship between the aesthetic properties and user material sorting actions of lightweight dispersion-coated and uncoated paper substrates. Unlike previous literature, no labeling or graphics were involved in this study, focusing on the physical and aesthetic properties of both coatings and substrates. Untrained panelists participated in a multi-phase (descriptive and hedonic) analysis involving a questionnaire and antonym scales about samples' visual and tactile properties, which were also characterized. The results highlight a remarkable panelist's ability to assess the relative gloss and roughness. Perceived roughness and mattness statistically significantly correlated to cellulosic material identification. Moreover, material sorting into the paper recycling stream was statistically significantly regulated by sample mattness, followed by sample roughness. This work suggests that, without any graphic or textual information, the combination of substrate characteristics and coating formulation strongly impacts the packaging aesthetics, hence packaging perception as paper-based material. Consequently, the correct material identification and sorting can be encouraged by proper packaging materials selection and coating development. [ABSTRACT FROM AUTHOR]

The environmental impact of industrial technologies and related remediation methods are major research trend lines. Unfortunately, in the development of materials for wastewater treatment or air purification, hazardous reactants are often employed, reducing the overall beneficial contribution of such technology on the environment. We here synthesize stable titanium dioxide (TiO2) sols using a green route, with titanium tetraisopropoxide (TTIP) as precursor, water as solvent and acetic acid acting as catalyst, chelating agent and peptizing agent. The sol was deposited on glass by dip-coating and then analyzed using XRD, SEM and spectrophotometry. Wastewater purification ability was evaluated in the photocatalytic degradation of two organic dyes (Rhodamine B and Methylene Blue). Results on RhB showed > 85% degradation in 6 h maintained along a series of 7 tests, confirming good efficiency and reusability, and 100% in 3 h on MB; efficiency mostly depended on calcination temperature and layer thickness. High photodegradation efficiency was found in nonannealed samples, suggesting TiO2 nanoparticles crystallization during sol–gel production. Yet, such samples showed a gradual decrease in photoactivity in repeated tests, probably due to a partial release of TiO2 particles in solution, while on calcined samples a good adhesion was obtained, leading to a more durable photoactive layer. [ABSTRACT FROM AUTHOR]

COVID-19 deeply changed traditional teaching, forcing the adoption of emergency remote teaching (ERT). ERT provided flexibility to teaching/learning activities (TLAs) yet affecting face-to-face communication and sociality. In this work, we present specific constructive alignment for an ERT/extended classroom course at Politecnico di Milano, as well as the tools involved. Two tutorials introduced the learners to the final essay, encouraged collaborative discussion, and promoted self-learning. The final essay, to be done individually or by joining a group, was part of the evaluation alongside a written exam. An evaluation rubric was shared when launching the topics of the essay, and setting the evaluation criteria. Results show how almost half of the essays were delivered by learners working alone, despite the attempts to promote collaborative interaction. Additionally, synchronous class attendance was only 55%, attributed to the availability of recordings and slides. Among the unattended results, the learners positively perceived TLAs and generated new collective knowledge, which was shared on the research group's Instagram profile. [ABSTRACT FROM AUTHOR]