Sheet Sheeted reclaimed rubber

The percentage sulphur (determined in the un-vulcanized reclaim) and the available rubber hydrocarbon are taken into consideration while evolving the compound formulation. It should be noted that reclaimed rubber is not all rubber. In arriving at the total rubber content in the rubber formulation containing reclaim, allowance must be made for its rubber content. For example in the following blend of smoked sheet and whole tyre reclaim, the total rubber content is to be considered as 100 parts instead of 125 parts as below and the proportion of other ingredients should be worked out accordingly on "parts per hundred rubber" (phr) basis. 

In another study, the ground reclaim rubber was blended with stirene-butadiene rubber and cured under pressure at 160°C. The cured sheets were silica-reinforced by soaking in tetraethyl ortho silicate, then in an aqueous solution of n-butyl amine catalyst, followed by heat treatment at 50°C. The tensile properties of the blends containing conventionally incorporated silica, with no coupling agent, were superior to those containing silica incorporated by the sol-gel reaction [21]. 

In addition to the two reviews that are mentioned at the beginning of this section, a number of other relatively recent reviews of the processes and methods that have been developed and evaluated for the devulcanisation of waste rubber are available. For example, Majumdar published an overview in 2009 in the Chemical Weekly journal [4], which covered the challenges that face workers in this field and covered the main types of systems that have been developed (i.e., chemical, microwave, ultrasonic and so on). This article also covered the production and use of rubber crumb from waste rubber. In another article [5], Majumdar reviews the three main sources of reclaimed rubber that are available in the marketplace (rubber crumb, rubber powder and chemically digested reclaimed sheet) and describes their properties and uses. 

Heater or pan process A steam autoclave is used at 100-300 psi for an extended time with ground rubber mixed with reclaiming agents, such as 20% ammonium persulfate solution. After the process, the product is mixed with an aromatic oil and formed into sheets. 

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