Mechanical characterization and sustainability assessment of recycled EVA for footwears

Ethylene vinyl acetate (EVA) is a thermoplastic material largely used in the footwear industry. Indeed, it is employed to produce outsoles and midsoles with high shock absorption. For producing these parts of the shoes, EVA is injected into a heated mold. During this process, gates and runners, which are necessary to allow a correct infill of the mold, are generated and they are treated as scraps and disposed in landfill. In this paper, a method for recovering pre-vulcanized EVA waste is presented and the possibility of developing a recycled product is investigated. EVA waste was shredded and dispersed into virgin EVA with a weight content of 10%. This mixture was employed in an injection molding process to produce samples for characterizing tensile, compression, and abrasion resistances and compare them with those of virgin EVA. At the same time, the environmental sustainability of the recovery process was evaluated through the standard methodology of Life Cycle Assessment (LCA) by comparing the production of recovered outsoles with traditional virgin ones. The LCA was paired with a Life Cycle Costing analysis to quantify possible economic benefits of the innovative system. Even though the resistances are quite lower than the virgin EVA, the recycled one demonstrates remarkable benefits in terms of environmental and cost sustainability, paving the way for a zero-waste system to produce outsoles and, more in general, EVA components.