What Is The Compounding Of Rubbers? Additives And Reinforcements

What Is The Compounding Of Rubbers? Additives And Reinforcements

In most rubber applications, both natural and synthetic rubbers are not used single-handedly. Because there can be other mechanical and physical feature requirements changes from application to another application that rubber materials are used.

To obtain these additional features from rubbers, some additives or reinforcements are used. Here, you will find a brief information on some additives and compounds are used in rubber part production.

Additives Used In Rubber Compounding

There are several additives are used in rubber compounding applications. The most important compounding operation of rubbers is vulcanization. Vulcanization is the chemical process that is applied to increase the density of cross-linking between rubber molecules. So rigidity and other mechanical properties can be achieved with vulcanization. Vulcanization is generally made with sulfur addition.

Carbon black is obtained from soot.

Another compounding process of rubbers is the addition of carbon black which is a colloidal carbon mixed with water. Carbon black is obtained by the thermal decomposition of soot which is a basic hydrocarbon. If the rubber is compounded with carbon black, tensile strength and abrasion, and tearing resistance of produced product will be increased.

You know that most of the automobile tires are black in color. This is because of the addition of carbon black into the rubber which is a compounding material of tires.

Calcium carbonate can be also used as a nonreinforcing filler to obtain much more volume of material. Another nonreinforcing filler is silica. But depending on the particle size, silica can act as reinforcing filler inside the rubber.

Hydrous aluminum silicates are also used as a reinforcing agent in rubber. When compounded with rubber, it gives tensile strength and abrasion resistance. If we compare with carbon black, carbon black is superior in terms of the addition of these features to rubber. But, hydrous aluminum silicates can be preferred if the black color is not desired in the application.

Rubber is also compounded with other additives to prevent aging which are also called aging retarders. Ozone-protective additives are also very important compound elements of rubbers.

When a rubber part is produced by using molds, mold release compounds are also added to rubber. Plasticizers are also important compounds of rubbers.

Reinforcements In Rubber Products

Steel-belted radial tire overview(Image Source: razitire.com).

Fiber reinforcement is one of the most important applications of rubber products. Glass fibers can be used to obtain much better mechanical properties from rubber products.

Also, steel fibers are used in tire production. Steel fibers give lower extensibility to tires but better mechanical properties to resist conditions that dynamically use by automobiles.


Rubber products without any compoundings or reinforcements are generally useless in terms of the physical applications that they will be used in.

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