ABSTRACT

The nature of the tire and rubber industry has changed over the last 30 to 40 years in that, like all other industries, it has come to recognize the value of using renewable sources of raw materials, recycling materials whenever possible, and examining the potential of reclaiming used materials for fresh applications. Renewable raw materials range from natural rubber, more of which is used than any other elastomer, naturally occurring process aids such as pine tars and resins, and novel biological materials such as silica derived from the ash of burned rice husks. Naturally occurring materials include inorganic fillers such as calcium carbonate, which is distinct from naturally occurring organic material, whose total supply may be restricted. Considerable work is underway today to develop markets and applications where rubber products can be recycled into existing new products and new applications developed for discarded rubber products such as tires. Given the desire to maximize the content of renewable, recycled, and reclaimed materials in rubber compounds, this review merges these topics under one title and treats each in turn.