Researchers at a start-up, green-chemistry firm in British Columbia have come up with an all-natural, biodegradable engineering polymer—a family of filled polylactic acid (PLA) thermoplastics—that offers greater strength, flexibility, and resistance to impact stresses than previously available PLA materials.
“We’ve developed the ability to combine novel, bio-based additives with PLA in such a way that maintains biodegradability of the final material,” said Toby Reid, founder and president of Solegear Bioplastics Inc. in Vancouver. “Traditionally, polymer compounders have added synthetic or mineral inputs to PLA,” which often undermines the purpose of using the starch or sugar-based plastic. “Our innovations in formulation and processing will allow automakers to do things with PLA that were previously believed to be impossible.”
Solegear’s extra-durability Polysole XD grade, which is suitable for film, sheet, blow-molding, and injection-molding applications, “offers performance that is comparable to nylon-6 in terms of tensile, flex, hardness, and impact properties at a cost premium of only 6 to 8%,” Reid said. As a creator of intellectual property and a specialty compounder, the Canadian company plans to market its proprietary bioresins directly to manufacturers in the form of meltable pellets.
The business research and consulting firm Frost & Sullivan recently recognized Solegear with its 2010 North American Award for New Product Innovation of the Year.
In automobiles, the new biodegradable plastic is aimed at “interior semi-structural or decorative applications such as inside door-trim components,” said Ed Trueman, Solegear’s CEO. “We’ve looked, for example, at a wood-grain, overmolding for a steering-wheel application with several Tier 1 suppliers.”
Polysole XD is also applicable to electronic parts and fasteners. Trueman reported that “mechanical engineering groups at North American OEMs are now writing new specs” for the biodegradable bioplastic in preparation for efforts to get its material properties approved and prove part performance for eventual use in cars.
As with most other plastics, the Polysole XD is unsuited for high-temperature, under-the-hood applications or exterior uses that involve direct exposure to sun and atmosphere, Reid noted. “We're not making mud flaps with it,” he quipped. “Like any polymer, our material suffers from UV exposure, but it’s not going to fall apart.”
Reid explained that PLA breaks down only through a catalytic process that requires four conditions: the presence of soil, heat, moisture, and certain microorganisms. “Without one of the four conditions, the material retains its integrity,” he said. Once exposed to all four simultaneously, however, Polysole XD decomposes in 6 to 14 months.
The new material formulation stems from the work of a team of five scientists who came together four and a half years ago in an R&D program to develop a truly biodegradable engineering plastic that suffers no performance penalty. The effort received support from both the University of British Columbia and the National Research Council of Canada. Reid has since assembled a management team to commercialize the enterprise, which to date has arranged about $4 million of business for 2011.
“PLA is essentially hydrophilic, while the inputs are somewhat hydrophilic, and water, which is a contaminant in polymers, is a challenge to remove,” said Trueman. “Our engineers figured out how to efficiently reduce moisture levels to extremely low levels—internally, less than 100 parts per million.” The other main innovation that makes the new material possible, he said, was perfecting the rheology of the injection-molding process to ensure full encapsulation of the reinforcing additives.
Solegear researchers have also developed Traverse Recycled polymer grades, which combine recycled conventional plastic—polypropylene, polyethylene, polyethylene terephthalate, nylon—and a customized fraction of bio-based fiber content—wood, hemp, bamboo, rice husks—from 20 to 60%, by volume. The low-cost additives, Reid claimed, can save manufacturers money by replacing some of the more expensive resin that they would otherwise use.
The company's alternative, Traverse Prime formulation, combines virgin (new) conventional plastic and natural fibers.