NEC Corp. is developing a new durable bioplastic that mates
cellulosic material from plants with cardanol, a byproduct of
cashew processing.
The technology is significant for design engineers because most
bioplastics lack adequate durability for electronics applications. The new polymer, which
will not be commercialized until early 2013, is also significant because more
than 70 percent of the compound is made of plant materials. Many bioplastics
are heavily loaded with oil-based additives or are blended with oil-based
plastics to improve strength and thermal resistance.
"One of the main appeals of our cellulose and cardanol
bioplastic is its durability when compared with existing products and potential
application for a wide range of uses," says Joseph Jasper, a press officer of
NEC Corp.
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After enhancing its reactivity, cardanol is chemically bonded with cellulose, which NEC says produces a durable thermoplastic that is strong, heat- and water-resistant and non-crystalline, due to the bonded cardanol's unique molecular structure consisting of flexible and rigid parts.
"Although there aren't any specific modifications with other plastics that we are preparing to announce, NEC will continue to seek improvement with its products and technologies," Jasper told Design News.
NEC says the new bioplastic has important advantages compared to polylactic acid, a widely used and fast-developing bioplastic, and cellulose acetate (CA), which has been widely used as a photographic film base.
- Molding time is less than 50 percent of PLA because of its noncrystalline chemical structure. Its molding time is comparable to conventional cellulose-based and petroleum-based plastics.
- It has twice the strength of existing PLA, and is comparable to conventional CA resin.
- It has more than twice the heat resistance (glass transition temperature) of PLA, and approximately 1.3 times more than CA resin.
- Water resistance is comparable to PLA, and approximately three times more than CA resin.
"It is expected that NEC's cellulose and cardanol bioplastic could become available at a lower price than existing polylactic acid-based plastics," says Jasper. "In terms of further price comparisons, NEC's latest bioplastic is expected to be competitive with petroleum-based plastics as well, but we do not have any specific figures at this time."
Several researchers have been looking for expanded opportunities to use cardanol, an oil-like material that is extracted from cashew nut shells. Cardanol is already used in resins, coatings, frictional materials, and surfactants used as pigment dispersants for water-based inks.
Cardanol-phenol resins were developed in the 1920s by a chemist named Mortimer T. Harvey. They have a coefficient of friction that is less sensitive to temperature changes than phenol-formaldehyde resins, and are used for vehicle brakes.
NEC says that only a fraction of the cardanol obtained from cashew nut processing is used in the industrial field.
Cashew nuts are widely cultivated in India and Vietnam. NEC says it is ensured of a stable supply of Cardanol as an additive for resin composites to produce finished products.
The newly developed bioplastic was formally announced today at The Chemical Society of Japan/Kanto Branch meeting at the University of Tsukuba.
One remaining issue is who will actually produce the resin. "Manufacturers are being taken into consideration, but none has been decided at this time," Jasper says.
