With depletion of natural resources and growing awareness of the limited capabilities of the globe to cope with pollution, the need to design lifetime recycling loops for all types of products is steadily increasing. Rubber articles of all sorts and the need for a proper disposal of these at the end of their life cycle cannot escape this trend, and also come more and more into focus.
Most conspicuous in this context are tires, of which about 800 million are scrapped worldwide on a yearly basis. If piled up at a height of 25 centimeters each, it establishes a pile of 200,000 kilometers—two-thirds of the distance to the moon per year. Apart from the environmental problems which these scrap tires represent, they actually also are a source of valuable materials if they can be recycled and reused in proper ways.
This paper reviews the latest developments in recycling: devulcanization of rubber articles, including tires of various sorts; and the contribution which the research in the University of Twente has played in this field. It highlights what has been achieved for different major rubber types, but also what the hurdles are to be taken before rubber recycling is as obvious a technology as the manufacturing of first-use rubber articles.