A sustainable approach toward mechanical recycling unsortable post-consumer WEEE: Reactive and non-reactive compatibilization.

While near-infrared (NIR) spectroscopy in post-consumer waste electrical and electronic equipment (WEEE) recycling accurately separates white or clear polymers, 40% containing dark plastics, termed 'unsortable WEEE,' are excluded from sorting lines and therefore incinerated or landfilled, causing environmental concerns. This study investigates the potential of using non-reactive and reactive copolymers as compatibilizers to enhance the performance of unsortable WEEE plastics free of brominated flame retardants. To the best of our knowledge, this is the first time that such copolymers have been explored as a solution for improving the compatibility of unsortable WEEE polymer blends. Initial trials with 4% of styrene-ethylene-butylene-styrene copolymer (SEBS-13) and SEBS-30-g-(maleic anhydride) copolymer (SEBS-30-g-MA MA) as compatibilizers showed insufficient results compared to virgin commercial polymers. However, the addition of higher concentrations of compatibilizers (i.e. up to 20 wt%) and the use of a SEBS having a higher styrene content (i.e. SEBS-30) improved the mechanical properties of the material, causing it to transition from brittle to ductile. This behavior was found more pronounced for the 20% non-reactive SEBS-30, for which the SEM analysis showed reduced phase segregation and revealed a more homogeneous fracture surface. This was further supported by Differential Scanning Calorimetry (DSC) analysis, which showed evidence of an interaction between one or more polymer phases. With a room temperature performance equivalent to that of virgin conventional polymers, the SEBS-30 compatibilization approach has made it possible to consider using unsortable WEEE streams as recycled materials in commercial applications.

Modeling plasma loudspeakers.

This paper deals with the acoustic modeling and measurement of a needle-to-grid plasma loudspeaker using a negative Corona discharge. In the first part, we summarize the model described in previous papers, where the electrode gap is divided into a charged particle production region near the needle and a drift region which occupies most of the inter-electrode gap. In each region, interactions between charged and neutral particles in the ionized gas lead to a perturbation of the surrounding air, and thus generate an acoustic field. In each region, viewed as a separate acoustic source, an acoustical model requiring only a few parameters is proposed. In the second part of the paper, an experimental setup is presented for measuring acoustic pressures and directivities. This setup was developed and used to study the evolution of the parameters with physical properties, such as the geometrical and electrical configuration and the needle material. In the last part of this paper, a study on the electroacoustic efficiency of the plasma loudspeaker is described, and differences with respect to the design parameters are analyzed. Although this work is mainly aimed at understanding transduction phenomena, it may be found useful for the development of an audio loudspeaker.