New source of rubber in desert-loving shrub

Press, 2 September 1981, Page 20

New source of rubber in desert-loving shrub

The United States imports every ounce of its natural rubber — chiefly from Malaysia, where the rubber tree thrives.. This alarms the Federal Emergency Management Agency (F.E.M.A.). It is trying to stockpile 850,000 tonnes of natural rubber to be turned into tyres (primarily) in the event that supplies are cut off. So far, it has stashed away a mere 119,000 tonnes. Practical solutions? F.E.M.A. is promoting a rubber-rich, domestic shrub called guayule. The edge that rubber has on all other materials is that it is springy, durable and cheap. The combination has secured it something 1ike.50,000 applications, and a market worth over $2.5 billion a year in America alone.

To be sure, synthetic rubber now accounts for 70 per cent of this market. Synthetics can do some chores better than natural rubber (e.g. resist oil) and cost about the same per pound (about 50 cents for top grades). However, synthetic rubbers have two important drawbacks. First, they' are

From “The Economist,” London

made from petroleum feedstocks. Second, in certain respects they cannot match natural rubber's performance. A car tyre made wholly of synthetic rubber could not withstand big potholes, or dissipate the heat generated in screeching halts. So even conventional tyres need some natural rubber. Radial tyres need three to four times as much.

Rubber from the guayule plant appears to have all the technical advantages of rubber from plantation trees. It recently passed a United States Navy Department test for use in tyres on military aircraft. The two-foot tall shrub likes hot, arid climates so it does not compete for growing space with most other crops (cotton is the notable exception) or guzzle water (already in short supply in parts of America). The trouble is that it is expensive, costing an estimated 85 cents a pound to grow and extract. Unlike rubber trees, which conveniently exude rubber molecules in their sap, guayule shrubs hoard rubber in their cells. You cannot just

strip the shrub of its bark and wait for the rubber to seep out. Typically, the cellular mass of the shrub must be ground up and then rinsed with a solvent. Scientists at the United States Department of Agriculture and at private companies like Goodyear and Firestone are trying to come up with ways to cut costs. They are looking into possible uses for the by-products of the extraction process. Now the groundup debris of the shrub simply goes to waste. They are also trying to decide which of the 26 strains of guayule are best suited to commercial exploitation. Farmers beware: 16 strains contain no rubber at all.

If guayule does become competitive, it could do more than fill America’s stockpile appetite. The World Bank predicts that, by the late 1980 s, demand for natural rubber will exceed supply world-wide — mainly because higher-technology products are increasingly requiring the qualities of the real thing. At that stage, guayule rubber could find a huge market.