Rubber Compounds: A Primer

A question we are often asked is, “What ingredients go into rubber compounds?” This is an interesting question as there are many different types of rubber compounds and, even for the same compound, the mix of ingredients may vary from manufacturer to manufacturer.

Engineered rubber is composed of many different ingredients that include the base monomer, vulcanization agents, modifiers, fillers and plasticizers. A “compound” consists of specific ingredients, mixed in a ratio, and blended into a formulation that offers specific desirable chemical and mechanical properties.

Rubber Compounds: Common Ingredients

The following ingredients are found in many typical rubber compounds:

Polymers. These are the heart of a compound. Polymers are long molecular chains that are connected together (cross-linked) to improve their toughness and resilience. The base monomer (or monomers, when blended) is used to classify the type of rubber (i.e., Neoprene, EPDM or Nitrile). Polymers give a compound its particular properties and characteristics. They also largely determine how a compound will behave when it is further processed, such as by molding or extruding.

Fillers. Fillers are used to strengthen or add to a compound’s properties. For example, carbon black is often used as a filler in many compounds to add strength and impart a black colour.

Antioxidants. These ingredients prevent the oxidation that can break polymer bonds and reduce the service life and performance of a compound.

Anti-ozonants. These ingredients prevent or retard the degradation of the compound that may result from exposure to atmospheric ozone. Anti-ozonants protect a compound from the effects of aging.

Oils. Oils of various types are used in compound processing to alter the viscosity and hardness of the material.

Plasticizers. Plasticizers are used to impart the qualities of plastic to a rubber compound. Rubber compounds with plasticizers can have greater overall flexibility, low temperature properties, and resistance to aging.

Curing Agents. Curing agents, such as vulcanizers, promote the cross-linking of the rubber matrix. Curing agents are used to create superior chemical and mechanical properties for a compound.

In addition to the above there are other ingredients that can be used to create rubber compounds with different properties. As new ingredients are discovered that alter the basic properties of rubber, new compounds with different properties and uses are developed. Rubber compounding is an innovative science that seeks to develop new and better rubber compounds that can address applications and uses in today’s world.

At Canada Rubber Group (CRG), we offer a wide range of rubber compounds. To see the full range of compounds we offer, please see our Rubber Compounds page.

CRG can supply any of the compounds we stock by the sheet, as cut lengths, by the full roll, or as multiple rolls. As a leading gasket fabricator and materials provider, we maintain an extensive inventory of compounds at all times.

For more information on how CRG can service your rubber compound needs, please contact our sales department at