Natural and synthetic rubber/waste – Ethylene-Vinyl Acetate composites for sustainable application in the footwear industry

• The recycling of EVA-waste within the footwear industry was evaluated.
• Waste -EVA/NR, NBR, or SBR composites were produced by physical/mechanical methods.
• Composites including 10 and 20 phr of EVA-waste were produced at a laboratory scale.
• Composites were characterised aiming application in the footwear industry.
• Using 20 phr of EVA-waste, 3 prototypes of soles with good properties were produced.

The production of natural and synthetic rubber/waste – EVA (Ethylene-Vinyl Acetate) composites was performed using natural rubber, styrene-butadiene rubber or acrylonitrile-butadiene rubber and 10–20 parts per hundred rubber (phr) of waste. Several physical and mechanical properties of the composites were further determined according to the requirements of the footwear sector. Rheometry and ageing tests were also performed. The effects observed on the crosslinking formation during vulcanization of each composite were negligible. The flexion, density, hardness and abrasion of all composites, produced at a laboratory (10–20 phr) and industrial scale (20 phr), were not significantly affected by the addition of waste. The tear strength and the tensile strength were the most affected properties, namely for the Natural Rubber/Waste – EVA composites, where EVA acted as filler (tear strength > 13 N mm−1, breaking load > 15 MPa). The study confirms the possibility of a sustainable application of EVA – waste in the footwear industry through the production of eco-composites.

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