Recycling of Rubbers

Report 99 Recycling of Rubber, H.J. Manuel and W. Dierkes, Vredestein Rubber Recycling B.V. 

One of the concerns regarding both RUMAC and A-R highways is their recyclability. Old asphalt is typically heated and mixed with fresh material to create new asphalt. There is concern that when the rubber modified asphalt is reheated, it may catch fire or produce noxious smoke. The industry claims that this will not occur, and that recycling of rubberized asphalt has been successfully done in Sweden. However, many state highway departments are not yet convinced. 

While many studies have been carried out aimed at the feedstock recycling of rubber wastes by pyrolysis and hydrogenation processes (see Chapters 5 and 7), little information is found on the catalytic cracking and reforming of rubber alone. Larsen35 has disclosed that waste rubber, such as used tyres, can be degraded in the presence of molten salt catalysts with properties as Lewis acids, such as zinc chloride, tin chloride and antimony iodide. The decomposition proceeds at temperatures between 380 and 500 °C to yield gases, oil and a residue, in proportions similar to those obtained by simple thermal decomposition. 

The material recycling of rubber is only feasible within narrow limits. This applies above all to technical rubber articles such as bellows, sealing elements (radial shaft gaskets, O-rings, sealing profiles), tire tubes, rubber-metal dampers, etc. that are made up of a number of different types of rubber. 

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