Mitsubishi Motors Develops Green Plastic: Bamboo-Fiber Reinforced Plant-Based Resin

17 February 2006

Bamboo-fiber prototype

Mitsubishi Motors Corporation, with cooperation from the Aichi Industrial Technology Institute has developed an automotive interior material which uses a plant-based resin, polybutylene succinate (PBS), combined with bamboo fiber.

Parts made from the material will be used in the interior of a new-concept minicar, to be launched in Japan in fiscal 2007. Mitsubishi Motors has dubbed its independently developed plant-based resin technology, including this PBS-bamboo fiber resin, “Green Plastics.”

Mitsubishi Motors plans to substitute plant-based resins and quick-growing plant fibers for materials such as petroleum-based resins and wood hardboards used in car interiors. The use of these renewable plant-based resources, in principle, will add no CO₂ to the atmosphere. Mitsubishi Motors began developing the materials in conjunction with the Aichi Industrial Technology Institute in 2004.

PBS, the main component of the material, is a plant-based resin composed mainly of succinic acid and 1,4-butanediol. The succinic acid for the material will be created through the fermentation of sugar extracted from sugar cane or corn.

The new material combines bamboo fiber with PBS in order to increase its rigidity. Bamboo grows to its full height in just a few years, compared with the tens of years required for traditional timber, and as such may be called a potentially sustainable resource. Bamboo is available and can be grown in a wide variety of areas including Japan, China, and Southeast Asia.

According to Mitsubishi’s tests, this PBS/bamboo-fiber prototype achieves an estimated 50% cut in lifecycle CO₂ emissions over polypropylene, a widely used petroleum-based plastic. VOC (volatile organic compounds) levels are also reduced drastically over processed wood hardboards (roughly 85% in testing).

Other automakers, such as Mazda with its Ibuki concept, are also working with plant-based plastics for parts.