Bio-Composites Update: Bio-Based Resins Begin to Grow
Substituting agricultural for fossil-based feedstocks in polymer resins is not new, but maturing technology now promises composites less dependent on petrochemicals for their performance.
By Jeff Sloan, Editor-in-Chief | April 2008
A few years back, when a barrel of oil cost less than $50 (USD), the use of soybean oil and corn ethanol in resins for composites manufacturing was intriguing, interesting and environmentally responsible, but not an economic or resource imperative. That is rapidly changing. The cost of a barrel of oil recently raced past $100 ($110 as of this writing) and as a result, interest in development of sustainable resources is growing. Consumer and OEM calls for reduced weight, increased efficiency and a smaller carbon footprint in products that are made from or burn oil are loud and expected to get louder. The good news is that advances in biotechnology and genetic engineering are helping materials suppliers create soy- and corn-based derivatives that are increasingly capable replacements for petrochemicals in unsaturated polyester, polyurethane and even epoxy resin formulations. Bio-composites are here to stay, and understanding their potential role in future applications will be critical to any composites fabricator.
MARKET SIZE AND THE SLEDGEHAMMER
Source: OBIC
Soybean oil is an attractive derivative of the popular and populous plant. Its flexible chemistry makes it a suitable replacement for some of the petrochemicals used to manufacture composites resins.
One thing the U.S. has much of is 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 USB report emphasizes that the current global market for fiber-reinforced thermoset composites is 1.7 billion lb (771,000 metric tonnes). According to the USB, if all the thermoset resins that today could be replaced with soy-based ingredients actually were replaced, the potential market for soy-based resins would be 1.1 billion lb (499,000 metric tonnes), or 100 million bushels of soybeans. Corn ethanol, in addition to its use in some resins, also is becoming a major fuel source, stressing the overall supply of the world’s corn. Because of this growth, corn and soybean prices have steadily increased in the last year. Soybeans have increased the most dramatically, rising from $5.67/bushel in January 2005 to $10.10/bushel by the end of 2007. Corn, over the same period, has increased from $2.23/bushel to $3.73/bushel.
Despite this activity, the use of soybean oil and corn ethanol in resins and plastics is relatively nascent — although it does enjoy a storied history. Henry Ford in 1941 famously demonstrated the strength and impact resistance of his company’s all-plastic-body car concept when he took a sledgehammer to its decklid during the vehicle’s introduction. The car featured 70 percent cellulose fibers in a phenolic resin matrix extended with soybean meal, a by-product of the soybean oil extraction process. Although Ford’s bio-based composite proved the concept’s merit, it was quickly forgotten as the auto industry geared up to mechanize U.S. troops with steel trucks, tanks and other wheeled vehicles. Given oil’s abundance and low price at that time, petrochemicals soon proved to be the least expensive feedstock for plastics, with chemistries conducive to resin performance. Likewise, glass replaced cellulose as the composite reinforcement of choice. It would be several decades before agricultural sources were earnestly re-explored as viable feedstock alternatives.
Although soybeans and corn took a backseat to petrochemicals, their abundant supply kept them in the R&D labs of chemical processors, if not in mainstream products. It wasn’t until the mid- to late-1990s, as concerns about biodegradability, sustainability and the depletion of oil reserves were raised that commercial development of viable bio-based resins occurred.
MARKET DRIVERS TODAY
Initial bio-based resins development has 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 resin che-mistry requirements. Stephen Myers, director of the Ohio BioProducts Innovation Center (OBIC), based at The Ohio State University (Columbus, Ohio), points out that facilities and equipment already in place to produce soy-bean oil, corn oil and other derivatives for food and animal use provide a ready source of feedstock for new materials development.
Source: Ashland
The most recent and highest profile application of soy-based resins was in body panels on the John Deere combine, introduced in 2001. Ashland developed its ENVIREZ for this application, a glass fiber-reinforced unsaturated polyester resin made, in part, with soy oil and corn ethanol.
The OBIC was established in 2005 and is funded by a grant from the State of Ohio designed to encourage, fertilize and grow new technology. Ohio, says Myers, is particularly keen on bio-based materials development because it sees the technology as a near-perfect marriage of the state’s long experience in plastics and composites processing with its large and fertile agricultural base. The OBIC acts as a networking partner to link researchers, manufacturers and end users to foster innovation and development. The OBIC has three core functions — all focused exclusively on bio-based materials development: to fund investment in research, to establish academic networking for innovation and to link research to industry needs. Myers calls it “cell to sell” research, but ultimately the program is designed to meet the needs of the materials market. “Basically, we’re looking at projects that use genetics to biologically modify materials for use in composites and other materials,” says Myers.
Grown in abundance in Ohio, soybeans and corn are a major focus of the OBIC’s efforts. Myers sees a bright future in these plants as a resource for a variety of material types. “The more we increase the yield of the plant — barrels of oil per acre — the more attractive it becomes,” he says, noting that the program goes beyond mere fabrication of a market for a prolific plant and is more than a method for manufacturers to market themselves as environmentally sensitive. “‘Green’ isn’t what’s pushing this,” claims Myers. “It’s sustainability.” Manufacturers are looking for material functionality, cost reduction, risk mitigation, source diversity and novel chemistries. Agricultural resources, according to OBIC, offer a replenishable means to all those ends. “The plant kingdom offers thousands of varieties of chemistries, and there’s much, much more we have yet to discover.”
