rubbercompounding

Rubber compounding is the formulation and preparation of rubber compounds by blending a base polymer with fillers, additives, and cure systems to achieve specific properties for a given end use. The base polymer can be natural rubber (NR) or a synthetic rubber such as styrene-butadiene rubber (SBR), polybutadiene (BR), nitrile rubber (NBR), or neoprene. Typical ingredients include reinforcing fillers (carbon black, silica), oils and processing aids, antioxidants and antiozonants, waxes, resins, and curing agents (sulfur-based systems or peroxides). For silica-filled compounds, silane coupling agents are used to improve filler–rubber interaction.

The manufacturing involves compounding in an internal mixer to form a masterbatch, followed by a final mix on mills or in an internal mixer. The compound is then shaped by extrusion or calendering and cured (vulcanized) at elevated temperature. Control of cure is critical to prevent scorching and to set the desired crosslink density, which influences elasticity, strength, and abrasion resistance. Processing considerations focus on achieving adequate processability while ensuring consistent batch-to-batch properties.

Performance is evaluated through rheological properties, Mooney viscosity, tensile properties, abrasion resistance, dynamic properties, and aging resistance. Formulations are tailored for applications such as tires, belts, hoses, seals, and other rubber goods, with tires often requiring a balance between wear resistance, wet traction, and processing efficiency. Environmental and safety considerations include selection of aging stabilizers, processing oils, and approaches to recycling or reclaiming cured rubber where feasible.