How is Synthetic Rubber Made?

Synthetic rubber and  natural rubber share many desirable qualities, but between the two lie important distinctions. For instance, (based on the polymer selected) synthetic rubber is fairly easy to produce, more resistant to abrasion, grease, oil, and heat compared to natural rubber. Like natural rubber, synthetic rubber is highly flexible, but synthetic rubber maintains its flexibility even at low temperatures. With the right manufacturing methods, synthetic rubber can also be highly resistant to extreme temperatures and corrosion, making it a great component for many products. 

Read up on the history, making of, and applications for synthetic rubber in the second part of our two part series on the different types of rubber. 

Where does Synthetic Rubber come from?

Synthetic rubber comes from catalyzing monomers from cracked hydrocarbons. These monomers are polymerized to form long chains. Additions to the polymer chain such as butadiene, styrene, isoprene, chloroprene, acrylonitrile, fluorine, ethylene, and propylene produce various synthetic polymers. Rubber compounds are created by using these polymers with the addition of fillers, protectants, plasticizers, curatives, and other chemicals in various ratios to produce specific physical and chemical properties.

Silicone Rubber

Silicone rubber is also a synthetic elastomer composed of silicone polymers. Silicone is created by polymerization of silicon from sand or quartz. Many synthetic polymers have a carbon-carbon backbone, while silicone backbone is composed of silicon-oxygen. These chemical bonds give silicone rubber its high-temperature performance. Silicone rubbers are widely used in industry, and there are multiple formulations. Silicone rubbers are often one- or two-part polymers, and may contain fillers to improve their properties or reduce cost. Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures.

Prior to WWII

While many  credit the rise in demand for synthetic rubber to the second world war, the initial increase in synthetic rubber products can actually be traced back to a growing need for pneumatic bicycle tires in the 1890s. This demand (in part) led to the first synthetic rubber being polymerized in 1909 by a team of German scientists led by Fritz Hoffman, the patent holder for the world’s first synthetic rubber.

Later work during the 1930s brought about the creation of neoprene, one of the first successful rubber synthetics, and the first in a series of rubbers known as Buna rubbers.

During WWII

The onset of World War II cut off U.S. access to 90 percent of the world’s natural rubber supply. At this time, the United States had a stockpile of about one million tons of natural rubber, a consumption rate of about 600,000 tons per year, and no commercial process to produce a general purpose synthetic rubber. Conserving, reclaiming, and stockpiling activities could not fill the gap in rubber consumption. The Axis powers controlled nearly all of the world’s limited supply of natural rubber by mid-1942. 

President Franklin D. Roosevelt was well aware of the United States’ vulnerability due to its dependence on the threatened supply of natural rubber. In response, he formed the Rubber Reserve Company (RRC) in June 1940. The RRC established objectives for stockpiling rubber, including conserving the use of rubber in tires by setting speed limits and collecting scrap rubber for reclamation.

After the loss of the natural rubber supply, the RRC called for an annual production of 400,000 tons of general purpose synthetic rubber to be manufactured by the four largest rubber companies. On December 19, 1941, Jersey Standard, Firestone, Goodrich, Goodyear, and the United States Rubber Company signed a patent and information sharing agreement.

Firestone produced the program’s first bale of synthetic rubber on April 26, 1942, followed by Goodyear on May 18, United States Rubber Corporation on September 4, and Goodrich on November 27. In 1942, these four plants produced 2,241 tons of synthetic rubber. By 1945, the United States was producing about 920,000 tons per year of rubber, 85 percent of which was synthetic rubber. Of that 85 percent, the four major companies were producing 547,500 tons per year. 

Uses Today

As of 2005, more than 58% of rubber products contain synthetic rubber.

Silicone rubber has many great properties and is commonly used in a wide range of products. Silicone doesn’t degrade in high temperatures and is food safe, making it a popular choice for cooking and baking tools. Silicone muffin tins, spatulas, and many other tools have become increasingly popular in recent years. Many other consumer products contain silicone, such as sportswear, storage containers, electronics, cosmetics, and footwear.

Industry uses for synthetic rubber include automotive products, sealants, and insulators. Silicone can also be found in many medical products, such as tubing, syringe components, fluid management components, and more.
For more information on rubber (synthetic or natural) or a resource for rubber products, contact the engineers over at Apple Rubber.

How is Synthetic Rubber Made?