GONE RENEWABLE Synthetic rubber, produced using biotechnology.
86 percent of the tire’s environmental impact revolves around how it affects fuel consumption. Only 12 percent of the carbon dioxide emissions associated with tires arise from the raw materials and manufacturing.
Tire makers say that fuel economy improvements of 4 to 8 percent over conventional tires are typical for these energy-saving designs. The low-rolling-resistance designs use silica-based mineral fillers, rather than just the standard carbon-black reinforcing fillers, to reduce friction.
the research laboratories at several tire makers are making progress toward reversing the trend of increased petroleum content. One of the first to pursue this path was Sumitomo Rubber Industries, which has a global alliance with Goodyear in the Dunlop brand, for the Enasave tire it introduced in Japan in 2006. Among other changes, Sumitomo engineers substantially reduced the amount of petrochemicals by cutting the amount of synthetic rubber in half, to 11 percent of the tire’s composition from about 22 percent.
A company spokesman, Masatoshi Hayashi, said that the replacement material was a chemically modified natural rubber, chosen to offset the tendency of tires with a high natural rubber content to have poor traction in braking and cornering. To overcome this problem, the engineers altered the rubber chemically to produce a rubber compound with better grip in hard driving.
Sumitomo also cut back the amount of carbon black filler (usually produced from oil, coal or charcoal) in the Enasave’s tread compound while increasing the amount of fuel-saving silica filler, Mr. Hayashi said. Vegetable processing oil was substituted for its petroleum equivalent, and the compounds were reinforced with fibers made from plant cellulose.
Sumitomo has continued development. In 2008, the company introduced a prototype Enasave tire using ingredients that were 97 percent nonpetroleum-based, and by 2013 it hopes to market a new tire line that contains no petrochemicals at all.
Engineers at Yokohama Tire, working toward a similar goal, have come up with tires that are 80 percent petroleum-free, the company’s director of technical services, Dan Guiney, said. The Yokohama dB Super E-spec, introduced in Japan in 2007, uses chemically modified natural rubber and a processing oil that is derived from orange peels. The peels are shipped from orange juice factories near the tire plant in Japan.
Src & Text: [nytimes]
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