Natural Rubber

It all started nearly 300 years ago in 1736 in France, when a man named Charles Marie La Condamine introduced samples of natural rubber to an Academy of Sciences. Natural Rubber has a long and interesting history. To discuss the history of natural rubber here may be a little overzealous, so a few brief bullet points have been provided:

  • Christopher Columbus ostensibly journals about natural rubber in 1493, speaking about the balls made of a substance from the trees.
  • Natural Rubber is discovered in terms of commercialization by Charles Marie La Condamine in France.
  • Charles Goodyear vulcanizes rubber with sulphur in the winter of 1839. The story is quite interesting, and is worth a read.
  • John Dunlop invents the air-filled tire in 1882
  • The advent of World War II causes a shortage of rubber in the USA; this prompts government and commercial forces to unite to find an alternative to natural rubber. This movement prompts the commercialization of synthetic rubbers.
  • Natural Rubber is still used widely today for many products, including elastic bands, boots, erasers and many other products; natural rubber has been used for self-sealing tanks. The idea is that the gas will swell the rubber and reseal itself.
  • Natural Rubber is estimated to account for 20%-30% of the contemporary rubber market.

Natural Rubber’s main chemical compound is isoprene. It comes from the tree Hevea brasiliensis. Natural rubber originated in Brazil, but now comes from many other parts of the world, including Southeast Asia and South America. The elastic substance is extruded from the tree and poured into buckets simliar to the way sap is procured. After the buckets have been poured, the impurities are then strained out. Then, various chemicals are added into “fixture like” buckets to form a dough like consistency. The sheets are then rolled to get the desired surface area. Afterwards, the process usually takes water out to minimize the amount of volatiles in the rubber. There are many other nuanced steps, but in short sulphur is added later on, and then cured by different means. Sometimes the rubber is cured through an extrusion process, sometimes by calendaring, sometimes by molding.

Natural Rubber plays a big role in today’s industry. Natural Rubber even has a place on the ASTM D2000. The designation for natural rubber is typically AA, of course this could mean other rubbers but the test methods are as such. This means that the requirements are 70C for a heat resistance type, and no oil swell requirement for the class. The other designation for natural rubber under ASTM D1418 is NR. There are many benefits to natural rubber, as well as drawbacks.

Natural Rubber has great low temperature properties, and excellent damping properties, this makes natural rubber good for dynamic applications.

Natural Rubber unfortunately also offers properties that prove to be less than advantageous, including high oil swell, poor resistance to solvents and aggressive chemicals, poor environmental properties (including poor resistance to ozone).

NEDC is a leading supplier of natural rubber products. NEDC provides natural rubber in many configurations, including waterjet cuts, sheet-stock, die-cuts, and molded parts such as natural rubber O-rings. NEDC also offers natural rubber sponge die cuts, and waterjet cuts. NEDC also offers many other synthetic rubbers such as neoprene, and fluorosilicone.

If you have any questions on natural rubber feel free to contact NEDC’s sales department at sales@nedc.com.