99% of rubber is produced from rubber trees (Hevea brasiliensis). When cutting the bark of rubber trees, latex is produced, which is then converted into rubber. ISO 1817:2022: Rubber, Vulcanized Or Thermoplastic – Determination Of The Effect Of Liquids examines safe procedures for vulcanized and thermoplastic rubbers.
The History of Rubber Began with Ballgames
Roughly around 1600 BCE, the Olmec, Aztecs, and Maya, ancient civilizations in Mesoamerica, were the first to use rubber. They took the latex from the bark of rubber trees and boiled it into a small ball to use in a ballgame, similar to today’s basketball and football. It was discovered that when the tree (Hevea brasilineas) was cut open, it secreted an oozy milky fluid (latex) to heal itself. These trees were originally in South America, near the tropics. Since the discovery of boiling latex into rubber, more complex processes have been used by industries to create bulk rubber, which proved to be the driving force of World War II (1939-1945).
World War II Revolutionized the U.S. Bulk Rubber Industry
Bulk rubber was pertinent during World War II because it allowed for vehicles like Sherman tanks, which contained half a ton of rubber, military airplanes, which contained half a ton of rubber, and battle ships, which contained 20,000 rubber parts, to be used on the battlefield. Rubber plantations in Southeast Asia were under Japanese control, which decimated and halted 90% of the United States access of the natural rubber supply. Since rubber was of vast military importance, and the U.S. had a consumption rate of about 600,000 tons per year, it was clear that the nation needed to find a commercial process to produce synthetic rubber in bulk. Thus, President Franklin D. Roosevelt, in June 1940, formed the Rubber Reserve Company (RRC), which set objectives for stockpiling rubber.
The United States formed an alliance with rubber companies, and, on March 26, 1942, the representatives of the companies, academia, and the U.S. government agreed upon a “mutual recipe” to produce government rubber-styrene (GR-S) rubber to use in great quantity in World War II. The U.S. synthetic rubber industry was able to grow from annual output of 231 tons of general-purpose rubber in 1941 to an output of 70,000 tons a month in 1945.
ISO 1817:2022 Standard for Rubber, Vulcanized Or Thermoplastic
ISO 1817:2022 describes methods to evaluate the resistance of vulcanized and thermoplastic rubbers to the action of liquids. Liquids in the standard include current service liquids (e.g., petroleum derivatives), organic solvents, and chemical reagents. The standard details the methods necessary for determining the changes in the following properties—mass, volume, dimensions, extractable matter, hardness, and tensile stress-strain—after immersions in test liquids and after immersion and drying.
Defining Vulcanized and Thermoplastic Rubbers (TPR)
Vulcanized rubber is any type of rubber that has been hardened via the use of heat and sulfur. It is made from a curing process in which the rubber’s elastomers harden in response to heat and sulfur. Most rubber products are vulcanized, since it drastically improves their lifespan, function, and strength. Vulcanized rubber is found in erasers, children’s toys, conveyor belts, shoe soles, insulation, rubber-lined tanks, and rubber hoses. To learn more about the vulcanization process, read Vulcanizing Rubber.
Thermoplastic rubber (TPR) is a form of synthetic rubber. When heated, it melts into a liquid and becomes solid when cooled. Unlike natural rubber (latex) extracted from the rubber tree, TPR is manmade from the polymer styrene-butadiene-styrene. Once natural rubber has been vulcanized or cured it cannot be recycled; however, TPR can be recycled and remolded. TPR is used in shoe soles, injection molding, blow molding, extrusion, tires, and calendaring.
Why Is ISO 1817:2022 Important?
The action of a liquid on vulcanized or thermoplastic rubber can result in:
- Absorption of the liquid by the rubber
- Extraction of soluble constituents (especially plasticizers and antidegradants) from the rubber
- A chemical reaction with the rubber
ISO 1817:2022 is important to measure the physical and chemical properties following immersion and drying of the rubber with a liquid because the rubber’s properties can be profoundly altered, changing the rubber’s tensile strength, extensibility, mass, and hardness.
ISO 1817:2022: Rubber, Vulcanized Or Thermoplastic – Determination Of The Effect Of Liquids is available on the ANSI Webstore.