Compounding, a term that has evolved within the tire and rubber industry, is the materials science of modifying a rubber or elastomer or a blend of polymers and other materials to optimize properties to meet a given service application or set of performance parameters. Compounding is therefore a complex multidisciplinary science necessitating knowledge of materials physics, organic and polymer chemistry, inorganic chemistry, and chemical reaction kinetics. The materials scientist, when designing a rubber formulation，has a range of objectives and restrictions within which to operate. Product performance requirements will dictate the initial selection of formula ingredients. These materials must be environmentally safe, meet occupational health and safety requirements, be processable in the product manufacturing facilities, and be cost effective.
Compounded rubber has many unique characteristics not found in other materials, such as dampening properties, high elasticity, and abrasion resistance. Hence rubber has found use in applications such as tires，conveyor belts, large dock fenders, building foundations, automotive engine components, and a wide range of domestic appliances. The ingredients available to the materials scientist for formulating a rubber compound can be divided into five categories:
• Polymers : Natural rubber, synthetic polymers.
• Filler systems： Carbon blacks, clays, silicas, calcium carbonate.
• Stabilizer systems: Antioxidants, antiozonants, waxes.
• Vulcanization system components: Sulfur, accelerators, activators.
• Special materials: Secondary components such as pigments, oils, resins, processing aids, and short fibers.
Each class of materials is reviewed in this chapter.
