Properties of sound panels made from recycled footwear treads

Natural resources have been decreasing with the large expansion of the world's population. In order to supply raw material for production, new recycling approaches should be developed for waste materials. Worn shoes is one of the most common waste products that can be recycled for this purpose. According to the record, shoes are very complex products, as they can be produced from forty different materials, like leather, rubber, polymers etc. Especially the bottom layers of the shoes are made from sound absorbing materials like polyurethane, thermoplastic rubber and PVC. Because today's technology is not able to separate these materials from each other during recycling, they should be used in a homogenised state. Thus these parts were shredded into small granules and mixed. PU binder and hot press were used to obtain samples for tests. In this paper sound absorption, sound isolation, vibration isolation and thermal insulation properties of the tread mixture are investigated. In addition to that, the mechanical properties of the material were also investigated by measuring the compression strength of the material.