In this work, an upcycling strategy, aimed to upgrade the performances of recyclates deriving from sorting and mechanical recycling of mixed plastic waste recovered from the urban collection (UPW), is explored. To this aim, UPW samples are firstly analyzed to get information on their polymer constituents (type and relative amount), and then they are upcycled with the addition of different amounts of a polymer compatibilizer, a CaCO3‐based moisture absorber, and/or odor removers. All used additives give interesting benefits on processability and quality of the recycled UPW. In particular, the stiffness is increased up to ca. 22%, with the addition of 5 wt% of compatibilizer, and up to ca. 36%, with the addition of 5 wt% of moisture absorber, which also give better processability thanks to its moisture removal action. The odor absorber significantly reduces the smell of the recyclates, as found in preliminary odor recognition test sensory evaluation.
The paper provides an analytical and visual view of what actually happenedon the process sidein a fully instrumented, pilot-scale, air ascending-flow chamber of industrial type for salami ripening. Since ripening is always characterized by a-slow‖ dynamics and limited variations in process variables, the time course of the curing air temperature and humidity, as well as the sausage heart temperature, did not show rapid or incomprehensible transients. The monitored variables clearly showed limited amplitude oscillations due to the "go" and "stop" air circulation pattern, that is the sequence of phases with either forced or natural circulation in the cell as imposed by the supervision system for the automatic control of the chamber set points. The effectiveness of set point tracking was favorably assessed for the experimental tests. Then, comparisons were made between different measurements of the same variable, e.g., air temperature and humidity, monitored by probes at different heights in the chamber; similarly, the temperature measured by a TC at the heart of the sausage was matched to the curing air temperature in the chamber. From these comparisons and other crossed checks among data, it was possible to obtain static (e.g. the effect of the position on air temperature at equal height) and dynamic (e.g., the sausage temperature response to the temperature variations in the chamber) assessments of the process variables. All in all, the work done and its further exploitation offer a tool set for a real-time aid to a factory operator.
The management of post-consumer plastic waste (PCPW) is a real challenging issue due to difficulties in effectively identifying and sorting the collected plastics and in their mechanical recycling. Indeed, mechanically recycled post-consumer plastic waste usually shows poor performances compared to virgin materials, due to incompatibility between constituents, presence of degraded materials, hygroscopicity and bad odors. Compatibilizers and nanoparticles can help to improve recycled plastics quality, but to be chosen and dosed properly they require an in-depth knowledge and characterization of the raw waste. In this study, an analysis of polymeric materials obtained from the separation and mechanical recycling of post-consumer plastic wastes from urban collection as pellets (UPW) is reported. In particular, the experimental characterization was carried out in order to identify UPW composition, water content, physical-chemical properties and processability. It was found that UPW samples are mainly constituted of polyethylene (PE) and polypropylene (PP) in equal parts. UPW was submitted to a melt processing operation, using a lab-scale single-screw extruder, obtaining ribbons that were completely characterized. With the aim to investigate the effect of water content on the recycled material processability and performance, the recycling process was carried out both on undried and dried UPW pellets.
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