By Jeff Danner Jeff has worked in both the chemical and biotech industries and is the veteran of thousands of science debates at cocktail parties and holiday dinners across the nation. In his Common Science blog, Jeff aims to make technological and scientific concepts accessible to all.

Follow the Bouncing Rubber Ball

By Jeff Danner Posted March 5, 2012 at 3:06 am

For hundreds of years European explorers searched the world for El Dorado, a city of gold.  In fact, El Dorado was waiting for them underground in the form of liquid petroleum.  Petroleum is so amazing that it’s hard to wrap your mind around it.  As a liquid it flows, making it easy to transport when compared to other fossil fuels like coal or natural gas.  It’s got very high energy density, which means that you can release a lot of energy by burning a very small volume.  Further, the parts of petroleum that you don’t burn can be easily manipulated to make a boat, a bowling ball, a car door, a stent to fix your artery, a tire, panty hose, a shirt, aspirin, bottles, plastic wrap and a million other things.  I reviewed the ubiquity of petroleum as a raw material for nearly everything previously in “Everything Comes from Oil, Everything”.  Increasing scarcity or increased cost for petroleum will have a ripple effect through all of these products and therefore, in our everyday lives. 
 
To me, the story of rubber of over the last 150 years is a great lens through which we can view the ephemeral nature of the petroleum age.  Natural rubber comes from the sap of the Hevea brasiliensis, more commonly known as the rubber tree, which is native to the Amazon basin.  Natural rubber lacks strength and stiffness which, for thousands of years, limited its utility to being used for simple things like water proofing and bouncing balls.  It’s nice in a way to think of Inca children playing with rubber balls just like ours do today.
 
Then in the 1800’s, Charles Goodyear invented vulcanization, the genesis of Goodyear Corporation. In vulcanization natural rubber is reacted with sulfur which cross-links the natural polymers in the rubber, making it stronger, stiffer, and moldable.  The first significant product to be made from vulcanized rubber was inflatable bicycle tires that represented a vast improvement in comfort for the rider compared to a solid wheel, leading to a dramatic increase in bicycle ridership.  A few years later the automobile was invented and the global demand for rubber skyrocketed.
 
The rubber trees in the Amazon Basin, having co-evolved with other native species, including those which could harm it, tended to grow in isolation from one another.  This is a relatively common defense mechanism for plants.  The collection of sap from the trees to make the rubber was carried out by strenuous manual labor and involved long walks down jungle paths.  Once rubber became a valuable commodity, Western companies came in and cleared swaths of the rainforest to plant rubber plantations.  As is always the case when a vast monoculture is created, the pests and diseases that attack the rubber tree multiplied exponentially and wiped out the plantations. 
 
For a short while Brazil held a global monopoly on rubber production and the ruling class was becoming fabulously wealthy.  Opulent cities with ornate opera houses and grand promenades sprung up in the middle of the jungle.  Brazil made it a crime to export seeds of the rubber tree and devoted significant efforts to enforcement.  Not surprisingly, with so much money at stake, the blockade did not hold.  In 1875 Henry Wickam successfully smuggled 70,000 rubber tree seeds out of Brazil and delivered them to Kew Gardens in England.  Using Kew Gardens as a staging ground, the English then established rubber plantations in Sri Lanka, Malaysia and East Africa.  Now that Hevea brasiliensis was away from its natural enemies in the rain forest it was able to prosper in plantation settings.  By around 1920 the Brazilian share of the global rubber business dropped to less than 5%. 
 
During World War II, Germany was cut off from sources of natural rubber.  In order to be able to continue to make the tires needed for the war effort, German chemists developed a method to create synthetic rubber from petroleum. This pattern of replacing natural products with chemicals synthesized from petroleum is one of the dominant themes of the 20th century. 
 
After World War II synthetic rubber continued to replace natural rubber in most applications.  By the year 2000, synthetic rubber accounted for about 80% of global rubber consumption.  But then, due to the increased cost of petroleum and the leveling off of global petroleum extraction around the year 2006, the market share of natural rubber began to grow again.  At first this might sound like a good thing, returning to a “natural” product instead of using a “synthetic” one.  But when you look a little deeper, there are quite a few flaws in this notion.  Consider these.

  • There’s not a lot of “natural” in natural rubber these days.  The tree has been transported half way around the world from the Amazon Basin to Southeast Asia where it’s being grown in plantations carved out from the rain forest.  Recall from “The Secret Life of Vegetable Oil” that this same rain forest is also being rapidly replaced by palm oil plantations for biofuels.
  • It is not possible for enough natural rubber to be grown to replace the lost volume of synthetic rubber which will be created by declining petroleum supply. 

 
The basic assumptions of governments and economic projections around the world include the view that there are still going to be lots of and lots of new car tires in the future, when, if fact, there will be fewer.  We are not remotely prepared for a world with fewer cars. Maybe a crisis in the supply of car tires will finally catch people’s attention?  We’ll know soon enough.
 
Have a comment or question?  Log in below or send me an e-mail to commonscience@chapelboro.com.

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