Researchers at Durham University in the United Kingdom have developed an innovative approach to break down rubber in materials at room temperature. The chemical process uses catalytic disassembly, thus eliminating the energy-intensive methods of the currently-used tire recycling methods.Keeping it cool articleIn a paper published in the journal Green Chemistry, the Durham researchers have explained the whole process and how it could be used to recycle vehicle tires, latex gloves, and other polymer-based items, which are manufactured in the millions of tons every year. The long-chain hydrocarbon molecules and unsaturated carbons in these rubbery materials are traditionally very difficult to recycle or reprocess easily, which holds true especially for vehicle tires.

The traditional method for reprocessing rubber is to drastically change the temperature of the rubber compounds to break them down, either by heating them for milling, or freezing them to fracture them. These are energy-intense and leave a crumb product which is then mixed with new elastomers to produce new material, often with a loss in hardness or malleability. These losses mean that most recycled rubbers are not re-used for the purpose they were originally formed, but are instead recycled into other products.

According to the Durham researchers, their chemical process may be used to allow the materials to be recycled back into their original use – so a recycled tire could be made into a new tire. Their cross metathesis reaction breaks down rubbery polymers into viscous liquids that can then be reformed without degradation. The process could also be used to create the crumb now commonly produced, but at much lower cost.

The process discovered is using Grubbs’ catalysts to break down polybutadiene (PBd) networks at their double bonds via cross-metathesis (CM) reactions to produce readily soluble molecules. As the chains are fragmenting, the material are disintegrating into rubber crumb at room temperature. Grubbs’ catalysts are easily synthesized and readily-available commercially.

The researchers also discovered that increasing temperature and reaction time improved the breakdown process, also offering a faster way to facilitate rubber compound breakdowns when producing crumb. The resulting oil is low in molecular weight and non-polymers (oligomers), both conducive to easy re-use of the polymers being recycled.

Article and Image Source: Gizmag