What is Polyisoprene?

The term “polyisoprene” refers to a polymer material with a specific base polymer: cis-1,4-polyisoprene. Polyisoprene can be derived from plant-based sources—as natural rubber latex—and petroleum derivatives—as synthetic polyisoprene.

Benefits of Synthetic Polyisoprene

Synthetic polyisoprene shares many highly desirable properties with natural rubber latex, such as excellent tensile strength, without the risk associated with latex allergies or sensitivities. Synthetic polyisoprene is resistant to abrasion, low temperatures, weathering, and chemicals, making it a durable choice for high-performance applications and intense service environments. Additionally, synthetic polyisoprene is great for manufacturing due to its excellent processability, purity, and consistency.

History of Polyisoprene

The rubber tree, H. brasiliensis, was grown exclusively in Brazil for years, but that didn’t stop people from trying to grow it in northern climates. There are even records of British explorers smuggling tens of thousands of H. brasiliensis seeds across the Atlantic Ocean to London Kew Gardens. Those smuggled seeds were used to establish the first southeast Asian rubber plantations, which now dominate the natural rubber market.

But with production limited by geography and the slow growth of H. brasiliensis trees, it wasn’t long before scientists began exploring a synthetic alternative. The path to discovery was incremental and shaped by the work of many people over many years.

Recorded attempts to create a synthetic version of natural rubber can be traced back to the early 1880s, when a British chemist named Sir William Tilden managed to obtain the world’s first synthetic isoprene from turpentine. However, his process took weeks, making it too inefficient to be commercially viable.

In 1906, the Elberfelder Farbenfabriken Friedr. Bayer & Co. dye factory announced a contest: Any employee that could come up with a method for creating a synthetic rubber substitute could win 20,000 marks. This was roughly equivalent to fifteen years of pay for the average worker.

One of the company’s head chemists, Fritz Hofmann, became the first person in human history to successfully polymerize synthetic rubber. The German Chemical Society awarded him the Emil Fischer Medal for his work, which served as the foundation for synthetic rubber development today.

In 1911, two scientists named Carl Harries and Francis Matthews discovered independently that introducing sodium accelerated the polymerization process of isoprene, furthering the work of Tilden and Hofmann. But a commercially viable method remained out of reach.

Throughout the first half of the 20th century, scientists successfully created a variety of synthetic rubber materials, namely styrene and butadiene. These products proved valuable for a variety of applications and are still widely used today. However, neither could replace synthetic rubber.

The start of World War II in 1939 led to a massive spike in demand for synthetic rubber. The United States was cut off from 90% of its natural rubber sources, and despite the country’s earlier efforts to stockpile the material, their backup stores dwindled quickly. Not even an aggressive campaign for citizens to cut back on rubber consumption could solve the problem, further highlighting the need for a synthetic alternative.

Companies and universities began sharing patents and research findings as part of a nationwide effort to find a solution.

But it was a German chemist named Karl Ziegler who inadvertently moved the industry forward. Ziegler was experimenting with ways to synthesize polyethylene when he tried introducing salts. He refined the process over time, creating a polymerization process that surpassed any other method that had already been discovered.

In 1952, Ziegler shared his work with an Italian chemical engineer named Giulio Natta. Natta used Ziegler’s method to produce stereoregular polymers, using a process that would eventually be named the Ziegler-Natta catalyst. Their work forever changed the face of large-scale synthetic polymer production.

In 1955, the Goodyear Tire & Rubber Company used a Ziegler-Natta catalyst to create a synthetic polyisoprene that closely matched the material and performance properties of natural rubber. In 1962, Goodyear released NATSYN, the world’s first commercially available synthetic polyisoprene that achieved the crystallization properties of natural rubber. One year later, Ziegler and Natta won the Nobel Prize.

Polyisoprene Today

Since Goodyear released NATSYN in 1962, many other companies have created and released their own synthetic polyisoprene compounds, and synthetic polyisoprene has become a popular choice for a wide variety of applications.

Uses of Polyisoprene

Synthetic polyisoprene is in high demand for medical and surgical tubing and other components for several reasons:

  1. Synthetic polyisoprene poses no risk for individuals with latex allergies or sensitivities.
  2. Its excellent purity properties make it a safe choice for sterile environments.
  3. Synthetic polyisoprene is durable enough to handle the fast-paced intensity of a medical environment.

A lot of food and beverage tubing is made from synthetic polyisoprene for the same reasons.

Synthetic polyisoprene has many consumer applications as well and is used in everything from tires to shoes to rubber bands. It’s also a popular choice for baby products because it’s soft and hypoallergenic.

Rubber Polymers From KEP

The team at KEP has years of experience working with synthetic polyisoprene and manufacturing highly customized products that meet our customers’ unique needs. Our facilities are equipped to produce high-quality tubing with a wide range of dimensions, thickness, and other variables, with tight tolerances and unbeatable quality assurance processes in place. We’re proud to offer on-site labeling and packaging services as well, to streamline the path to market and minimize the risk of supply chain disruptions.

To learn more about synthetic isoprene and KEP, get in touch.