Metal Fabrication: The Secret To A Great Roll Cage

An Explanation Of The Synthetic Rubber Manufacturing Process

by Sally Burke

The numerous advantages of synthetic rubber over natural rubber make it the material of choice for a number of applications. Its higher thermal stability, widespread availability, and capacity to be fine-tuned to a specific purpose with additives have made it the material of choice for car tires, mechanical belts, footwear, and many other industries. Here is an explanation of the modern synthetic rubber manufacturing process.


Synthetic rubber is formed through the polymerization of the raw materials 1.3-butadiene and hexane. These ingredients are kept in separate storage tanks and piped through alloy 20 stainless steel columns. You can read more about alloy 20 pipes here. The columns are heated to boil away any impurities in the ingredients before they combine and the polymerization process begins.

Butadiene and hexane are combined with a catalyst inside of a reactor to promote the polymerization process. Polymerization causes the colorless liquid hexane and gaseous butadiene to form a white, viscous liquid known as polybutadiene. Polybutadiene is a pure form of synthetic rubber, but it is seldom used alone. Instead, it is commonly mixed with additives to suit a particular purpose.


Inside another storage tank, a large whisk mechanism mixes additives into the newly formed polybutadiene. Additives that are commonly added are silica and terpene-phenolic resins. These additives enhance the durability and traction of the rubber to make it more suitable for heavy-treaded tires.

After it has been thoroughly mixed, the enhanced polybutadiene is piped into storage tanks. The storage tanks contain agitators to continually mix the polybutadiene so that the additives do not settle to the bottom of the tank. To make the synthetic rubber usable, a large amount of moisture must be removed to get the rubber into a semi-solid state. This is done through the process of coagulation.


Removing moisture from the synthetic rubber is a two-part process. First, the rubber must be coagulated into small crumbs with very little moisture content. To do this, the liquid rubber is piped into a crumbing machine where a solvent is added and the mixture is heated. The solvent separates water from the rubber, resulting in small crumbs of rubber floating in the water.

After the rubber has been coagulated, the contents of the crumbing tank are emptied into a rotating sifter. The spinning sifter removes much of the water from the rubber, but the rubber must be cooled to solidify. The rubber travels out of the rotating sifter onto a vibrating conveyor sifter, where it passes under cold water. The sifter continues to remove water from the rubber, and hot air is blown over the rubber on each side of the conveyor to allow it to fully dry.


At the end of the conveyor sifter, the synthetic rubber is passed into a baling machine. The baling machine first uses metal plates to squeeze the rubber and remove any remaining moisture. Once the rubber is completely dry, it travels down a chute to be baled and prepared for shipping.

At the bottom of the chute, the baling machine presses the rubber into large rectangular bales. The individual crumbs of rubber can no longer be seen, as they are compressed into a solid block of rubber. The bales of rubber travel down one final conveyor, where they are inspected by a factory worker. After they pass inspection, a machine heat seals the rubber bales in plastic and transfers them to the shipping station.

Synthetic rubber is one remarkable example of how human engineering has created a product that surpasses the natural equivalent. The manufacturing processes used to create synthetic rubber will continue to allow engineers to create unique and innovative materials in the future.