Recycled PP for 3D printing: material and processing optimization through design of experiment

In this work, blends based on virgin (PP) and recycled (r-PP) polypropylene were designed and formulated, aiming at producing filaments suitable for 3D printing (FDM). A preliminary characterization of PP/r-PP blends at different weight ratios allowed selecting two systems showing adequate rheological behavior for FDM process. The selected blends were melt compounded in a twin-screw extruder, optimizing the processing conditions through a design of experiments approach, involving the use of Taguchi’s method. The blend having the best performance in terms of rheological behavior and thermal characteristics was than selected for the production of the filament and for the subsequent FDM processing. Finally, the mechanical properties and the morphology of 3D-printed samples were also assessed

Is it Possible to Mechanical Recycle the Materials of the Disposable Filtering Masks?

In a singular period, such as during a pandemic, the use of personal protective masks can become mandatory for all citizens in many places worldwide. The most used device is the disposable mask that, inevitably, generates a substantial waste flow to send to incineration or landfill. The article examines the most diffused type of disposable face mask and identifies the characteristic of the constituent materials through morphological, chemical, physical, and thermal analyses. Based on these investigations, a mechanical recycling protocol with different approaches is proposed. Advantages and disadvantages of the different recycling solutions are discussed with considerations on necessary separation processes and other treatments. The four solutions investigated lead to a recycling index from 78 to 91% of the starting disposable mask weight. The rheological, mechanical, and thermo-mechanical properties of the final materials obtained from the different recycling approaches are compared with each other and with solutions present on the market resulting in materials potentially industrially exploitable

Development of disposable filtering mask recycled materials: Impact of blending with recycled mixed polyolefin and their aging stability

A survey on Covid-19 protecting masks habits carried out on the Italian population at the end of 2020 revealed that disposable face masks are the most used, thus resulting in a considerable quantity of waste. Therefore, a separate collection of these devices based on local platforms such as schools, offices and factories is proposed. This would limit collecting costs, ensure the origin and quantity and simplify the sanitizing treatment of the masks, in order to allow their introduction into the industrial recycling stream of plastic materials. In this scenario, an urban separate waste collection material (namely mixed polyolefin) was selected and melt blended in several ratios with the disposable filtering masks. Two recycling solutions have been envisaged: the use of the filtering part alone or the joint introduction of the ear loops. Compared to the mixed polyolefin, the resulting recycled materials from filtering face masks have lower viscosity but comparable toughness and superior stiffness and strength. The presence of ear loops in the recycled improves the rigidity but slightly decrease the viscosity and worsen both the strength and toughness. Furthermore, conceiving an outdoor application, the stability to photo oxidation was investigated through an accelerated aging process. The elaborated degradation rate of the masks material is similar to a commercial polypropylene, while for the mixed polyolefin is greatly reduced. The mixed compounds have intermediate degradation rates