Recycled rubber surface treatment

There are certain technical limitations in the devulcanization of rubbers, and vulcanization is, in fact, not truly reversible (Pryweller, 1999). The partial devulcanization of scrap rubber will result in a degradation of physical properties. In many cases, this may limit the amount of substitution levels in high-tech applications such as passenger tires. But it can provide the compounder of less stringent products with an excellent low-cost rubber that can be used as the prime rubber or at very high substitution levels. According to Franta (1989), reclaim cannot be used for tread compounds in tires because every addition may decrease their resistance to wear. However, this statement has not been checked in case rubber devulcanized without an addition of chemicals. Considerable amounts of reclaim are consumed for carcasses of bias ply tires for cars if the compounds are of NR for carcasses of radial tires no reclaim is added. On the other hand, reclaim is added to compounds for bead wires and it may also be added to sidewalls. Within the framework of direct recycling options a number of applications for GRT outside the rubber industry have been proposed. Such applications include the use as a tiller in asphalt for the surface treatment of roads and as a rubberized surface for sport facilities. 

X. V. Cao, H. Ismail, A. A. Rashid, T. Takeichi, and T. Vo-Huu, Effect of filler surface treatment on the properties of recycled high-density polyethylene/ (natural rubber)/(Kenaf powder) biocomposites. J. of Vinyl and Add. Tech. (2014). 

Surface mercuiy usually is in the metallic form. Simple washing of the surface can be very effective. High-pressure water can remove mercury quickly splash containment is necessary. Steel and rubber-lined pipework can be retorted or cleaned with HCI/CI2 or NaOH/H2C>2. These solutions oxidize the metal to the soluble Hg +. Heavily contaminated steel will sweat mercury. Lott [19] points out that broken concrete from a cell room floor also can sweat mercury if allowed to stand overnight. Components should be stored with this in mind. Liquid droplets can be collected. The storage area should be ventilated because of evaporation of the mercury. Buswork and copper fabrications are protected by surface films and usually are not seriously contaminated with mercury. Surface washing is good practice before recycle. Copper braid or flexible strips can be more heavily contaminated and require treatment in a mercury distillation oven. 

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