The global rubber industry has always been concerned over the fluctuating supply and spiralling prices of natural rubber (NR). Natural rubber is a highly valuable biomaterial in contrast with other bio-polymers and it cannot be replaced by other synthetic materials for many vital applications like heavy-duty truck/bus and aircraft tyres as well as many latex products. As such, it is the first choice for heavy-duty radial truck tyre manufacturers, especially because of its physical, mechanical properties and excellent adhesion to steel cord.

NR supply
Fluctuation in NR supply is mainly due to production cut and shifting towards other more profitable crops such as palm oil cultivation in major NR producing countries like Malaysia and Indonesia and Sri Lanka in a small way. Growing usage of NR in commercial vehicle radial tyre and growing demand in the fast-developing economies like China and India are also few among other many reasons.
Moreover, NR is also vulnerable to the effects of climate change, population growth, and economic developments. In fact, these unpredictable factors induce major changes in the available yield and demand for NR.

Competition from palm oil
The shift towards palm oil in some of the Southeast Asian countries had it’s tell-tale effects on NR supply. It was about two decades ago, palm oil emerged as the cheapest source of edible oil and has been garnering a lot of attention since then. Today, it is the largest produced, consumed and traded edible oil in the global markets.
Not only is it competitively priced compared with other major oilseeds, but it also has the highest yield. The palm oil tree yields an annual average of 3.7 tonnes of oil per hectare, which is much higher compared with the rapeseed (0.6 tonne) and soybean (0.45 tonne).

Usage in radial tyre
Radialization has of course increased the percentage usage of natural rubber owing to better green strength and steel cord-rubber bonding properties. A high level of building tack between the various layers of liner/carcass/tread/sidewall is essential for the modern day’s high-speed tyre building machines. All-steel radials required a higher level of green tack and green strength than conventional tyres. In these respects, natural rubber is superior compared to the other polymers used for making tyres.
It may be noted that more NR is used in tyres than ever before and the worldwide trend toward radial tyres is certain to ensure continued demand. These include its excellent dynamic properties, with a low hysteresis loss, and good low temperature properties, it can be bonded well to metal parts, it has high resistance to tear and abrasion and it is relatively easy to process. These are some of the distinct advantages that NR has over SR.

China and India
Today, China and India are the largest consumers of NR and the former, despite being the largest NR consumer in the world, has inherent problems in extending its limited rubber plantations. For example, the rubber planting areas in China are located in remote mountain areas or undeveloped areas.
Threat of extreme weather is more frequent than ever. Environment conditions in new expanded area are poor for rubber tree growth, where rubber trees take longer time to mature. The gap between local output and demand has to be met by imports.
India is also gearing up and due to an increase in presence of international players in India, there is a surge in the demand for NR and is reflected in the ranking of India at the third place in the world for consumption of NR. About 40% of the world’s NR production is consumed by USA and Japan. The last decade saw huge ups and downs in NR prices leading to a renewed interest in developing alternative crops for natural rubber production.
The hunt for alternatives to NR has a long history. During World War I & II, the Britons and later on Japan controlled most of the rubber supplies. During and after that war, a lot of people in different countries started to feel uneasy in that not only their military strength, but their industrial and economic strengths were dependent on the foreign rubber.

Volatility in prices
Although we may not be in immediate danger of running short of our primary source of natural rubber, yet the prices have been very volatile over the past 10 years, contributing to rising prices for tires and other end products of rubber.
The primary producers of natural rubber are in South and Southeast Asia with some production in tropical West Africa. All those are places subject to damaging seasonal monsoons and other extreme weather conditions, like the one that struck Thailand in 2011. That makes supply a little unpredictable.
Rubber has also recently become a traded commodity, leading to speculative investment, which has driven up prices.
“It’s not unlike petroleum markets,” says Bill Niaura, Bridgestone Americas’ director of new business development. “There are price points where it begins to make economic sense to explore and drill for oil in non-traditional areas. We’re now at the point in the rubber industry where it makes sense to look for alternatives.”

Enter guayule
There are about 2,000 plant species producing natural rubber, but the Hevea tree is the most productive. In the history of the rubber business, only one other species, guayule, has been used in actual rubber production.

In the 1920s, the Intercontinental Rubber Co. in California produced 1,400 tons of guayule rubber after leaf blight decimated the Brazilian rubber industry.
Guayule also become a replacement for Hevea tree-produced latex rubber during World War II when Japan cut off America’s Malaysian latex supplies, says Dennis T. Ray of the School of Plant Sciences, University of Arizona at Tucson. “The war ended before large-scale farming of the guayule plant began, and the project was scrapped.”

Unlike the hevea tree, which grows in tropical climates, guayule grows in the arid climates of the U.S. southwest – Arizona being particularly well-suited to the plant.
Hevea is essentially the sole source of natural rubber today, but active research and development programs are underway to domesticate and commercialize guayule – two are led by tire manufacturers Bridgestone and Cooper Tire & Rubber Co.

The BRDI is a joint effort between the USDA and the DOE to develop feedstocks for bio-fuels and bio-based products, including rubber from guayule.
The consortium members aim to harness biopolymers extracted from guayule as a replacement for petroleum-based synthetics and tropical-based natural rubber used in the manufacture of tires.

Meanwhile, Bridgestone has its own plans for a guayule research farm near Eloy, Ariz., and a research center in nearby Mesa, Ariz.
“Material-wise, guayule is the same polymer as hevea rubber, but it diversifies our supply,” Niaura says. “In terms of plant biology and regionality, it’s domestic to the Americas, but there are still challenges ahead. Guayule is not a commercial crop, so we have to develop the agricultural aspect as well as the process aspect.”
The facility is expected to be fully operational in 2014, with trial rubber production starting in 2015.

More rubber alternatives
Scientists from the Fraunhofer Society in Germany have discovered that the milky sap of the dandelion contains raw rubber of the same quality as that found in rubber trees.

While the commercial production of dandelion rubber is still only a vision for the future, Continental AG intends to pursue this alternative source of natural rubber for tire and technical rubber applications.

Continental has been pursuing the research into dandelion rubber since 2007, and is currently working in a research consortium to explore the capabilities of the Russian dandelion species, which provides a higher yield of natural rubber than the common dandelion.

Yokohama currently uses oil from orange peels in one model of passenger car tire, says Rick Phillips, director of commercial sales at Yokohama Tire Corp. “It’s an oil substitute that improves traction. It displaces some oil in just those tires at the moment, but we’re looking at ways to use it in commercial tires.” Goodyear is looking at soybean oil as a way to help reduce the amount of petroleum-based oil used in tires.

“Goodyear researchers have learned via testing that using soybean oil in tires can potentially boost tread life by 10%,” says Mike Manges, Goodyear’s Communications manager for commercial tires. “As well, Goodyear and DuPont Industrial Biosciences are working together to develop BioIsoprene, a revolutionary bio-based alternative for petroleum-derived isoprene (synthetic rubber).” (Reference, Rubber Asia, May/ June 2013).

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