A few years back, when a barrel of oil cost less than US$50, the use of soybean oil and corn ethanol in polymers for composites manufacturing was intriguing, interesting and environmentally responsible, but not an economic imperative. That is rapidly changing. The cost of a barrel of oil recently raced past US$100 and as a result, interest in development of sustainable resources is growing. The US has much of soybeans and corn, thus the opportunity for application of byproducts of these crops is substantial. The most commonly used soybean byproduct - polyol, comes from soybean oil. Corn�s most prominent byproduct is ethanol. The United Soybean Board (USB), in its 2007 report on soy-based thermoset plastics, identifies construction, transportation and marine as the end markets that hold the most promise for soy oil use in composite parts and components. Further, the report emphasizes that the current global market for fiber-reinforced thermoset composites is 770,000 tpa. According to the USB, if all the thermoset today could be replaced with soy-based ingredients, the potential market for soy-based polymers 500,000 tons or 100 mln bushels of soybeans. Corn ethanol, in addition to its use in some polymers, is also becoming a major fuel source, straining overall global corn supply.

Despite this activity, the use of soybean oil and corn ethanol in polymers is relatively nascent. The use of soybeans and corn in petrochemicals was very negligible, even as abundant supply kept them in the R&D labs of chemical processors. In the late-1990s, when biodegradability became a grave concern, and sustainability and depletion of oil reserves were raised that commercial development of viable bio-based polymers occurred.
Initial bio-based polymer development focused almost exclusively on the use of soybean and corn oil as a feedstock, but not necessarily because these plants are chemically the most adaptable to polymer chemistry requirements. Ashland eventually developed and commercialized ENVIREZ 1807, a soybean oil and corn ethanol-based unsaturated polyester polymer for SMC use. Tests of the material for mechanical and surface performance and paintability proved ENVIREZ comparable to standard SMC materials. Development of the Susterra material based on the PDO glycol shows that chemical innovation using biomaterials is expanding beyond oils. Ashland has launched a sizeable R&D effort in support of its ENVIREZ product line, recognizing that composite fabricators are unlikely to replace tried-and-trusted petrochem based polymers with bio based polymers unless the alternative offers easy replacement potential. Waterless Co., a manufacturer of no flush, water-saving urinals has used ENVIREZ 1807 in the manufacture of the company�s glass fiber urinals and passed all of the relevant performance and safety tests.

In the market for several years and particularly active in the food packaging sector has been NatureWorks LLC, a joint venture of Cargill and Teijin Ltd. NatureWorks produces a thermoplastic using a proprietary polyactide (PLA) polymer derived from plant sugars. Its capacity has reached almost 140,000 tons. The PLA can be thermoformed, extruded, injection molded and compression molded. To date, it has been used primarily to produce food containers, cups and service-ware because of the polymer�s optical clarity. However, Toyota has used the material, sans reinforcements, to compression mold spare tire covers. The larger question is how the material performs when reinforced with fiber.
NEC Corp., in April 2007 announced the development of a new bio-plastic that combines carbon fiber with a plant-based polyactic acid polymer. The material reportedly conducts heat more efficiently than steel and will be used in an NEC mobile phone. Available with carbon fiber loadings of 10 or 30% the composites offering heat diffusion properties comparable to and double that of stainless steel, respectively. NEC previously developed a kenaf fiber-reinforced polyactic acid polymer for a similar mobile phone.
Among the most active researchers of soy-based polymers for automotive has been Ford Motor Co. Dating back to Henry Ford�s era, the company has looked for opportunities to integrate soy into everything from seat foam to fenders. The most tangible result of this effort was the 2003 introduction of the Model U concept car, which used a glass fiber-reinforced soy-based polymer composite in the tailgate.
Metabolix in a JV with Archland Midlands Company, the makers of bioplastic Mirel have used biotechnology to grow polymers within the crop plants themselves. Metabolix also uses E.coli bacteria to create the PHA polymer within their cells. The company uses patented tools of modern biotechnology to use enzymes into microbial and plant bio-factories, to produce a broad, versatile family of useful polymers called Mirel (chemically related to polyesters). Mirel is based on the use of sustainable raw materials, ultimately carbon dioxide and water, transformed by the sun's energy through the process of photosynthesis. It degrades naturally in a wide range of environments including soil, home compost, industrial compost, and both fresh and salt water. It exhibits high performance properties including excellent strength and toughness, as well as resistance to heat and hot liquids. It is suitable for injection molding, extrusion coating, cast film, sheet, blown film, and thermoforming, and can be transformed into a variety of products from cosmetic cases and lipstick tubes to disposable coffee cup lids and hot beverage containers.
Lately, Metabolix, Inc. demonstrated switchgrass plants engineered using Metabolix multi-gene expression technology produced significant amounts of PHA bioplastics in leaf tissues. This spelled the first successful expression of a new functional multi-gene pathway in switchgrass, and exhibited its bioengineering capabilities as a powerful tool for maximizing the potential of switchgrass for both bioplastics and biofuels production. This was an important step for economic production of PHA polymer in switchgrass, and demonstrates for the first time an important tool for enhancing switchgrass for value-added performance as a bioenergy crop.

The above developments and other works throughout the industry make clear that the bio-composites and biopolymers market, although long-lived, is still in the very early stages of growth and development. However, the market forces that have spurred the most recent surge in biopolymer development are here to stay and inevitably will push more renewable, sustainable plant products into the composites.