Soy Proteins as Wood Adhesives

Protein-based adhesives have a long and ingenious history. Animal protein, casein from milk, soy flour, and even blood have historically been used as bonding agents for wood product applications. These proteins have allowed for the development of bonded wood products such as plywood and glued-laminated timbers in the early 20th century.


Casein proteins from milk were used to make glued-laminated arches, seen here in the construction of the former Building Two at FPL (1930s).

Petrochemical-based adhesives replaced proteins in most wood bonding applications because of lower cost, improved production efficiencies, and enhanced durability. Technological and environmental factors, however, have led to a resurgence of proteins, especially soy flour, as an important adhesive for interior nonstructural wood products. Among other factors, more stringent regulations limiting formaldehyde emissions from composite and wood panels have driven renewed interest in soy adhesive technology.

Charles Frihart and Christopher G. Hunt, both Forest Biopolymer Science and Engineering chemists at FPL, along with co-author Michael Birkeland, of AgriChemical Technologies, describe the value of soy proteins as wood adhesives in a chapter of Recent Advances in Adhesion Science and Technology (Gutowski & Dodiuk, eds.).

Their paper discusses important aspects of protein structure and recent successful advances in higher performance soy flour adhesives for wood bonding. Protein wood adhesives have recently displaced fossil fuel-based adhesives in some markets and have the potential to replace a significant percentage of fossil fuel-based wood adhesives worldwide.

Biological Properties of Wood

Rebecca Ibach, research chemist at FPL, has written a chapter for the new edition of the Handbook of Wood Chemistry and Wood Composites (2nd ed., 2013) titled Biological Properties of Wood.

Rebecca Ibach, FPL research chemist

Rebecca Ibach, FPL research chemist

Ibach is part of the Performance Enhanced Biopolymers unit at FPL.

Biological damage to wood and wood products (e.g., logs, lumber, or other products) occurs when it is not stored, handled, or designed properly. Biological organisms such as bacteria, mold, stain, decay fungi, insects, and marine borers depend heavily on temperature and moisture conditions to grow.

Among the many interesting bits of information in this chapter, one figure (Fig. 5.1) shows the climate index for decay hazard in the U.S. The index ranges from a low of 0-10 to a high of 150. The higher the number means a greater decay hazard. The southeastern and northwest coasts, for example, have the greatest potential for decay. Florida ranges from about 90 in the panhandle to a high of 150 around Fort Lauderdale. Alternately, the much drier American southwest has the lowest decay potential. An index level of 10 covers much of the Intermountain West including most of southeastern California, Nevada, and a thin stretch of central Oregon.

The Handbook chapter focuses on the biological organisms, their mechanism of degradation, and prevention measures. If degradation cannot be controlled by design or exposure conditions, Ibach suggests, then protection with preservatives is warranted.

Ibach’s other research interests at FPL include related topics such as:

  • Woodfiber-plastic composite durability
  • Laboratory and field evaluations
  • Chemical modification for improvement of wood properties
  • Integrated approach to wood protection
  • Solid wood polymer composites

Wood Water Filter Design Wins Regional Competition FPL Researcher Mentors Winning Student Team

A team of engineering students from the University of Wisconsin-Madison (UW) took first place in a recent American Society of Civil Engineers (ASCE) competition with a bit of guidance from FPL Research Chemist Mandla Tshabalala.

Winning water filter design using ponderosa pine bark as filter media.

Winning water filter design using ponderosa pine bark as filter media.

The contest, part of the annual ASCE Great Lakes Student Conference, challenged students from 18 regional universities to design and build a water filter for a hypothetical water stream contaminated with dissolved copper, molybdenum, iron, and phosphate. Filters were scored on cost, sustainability, and performance.

Students were encouraged to pursue filter materials that were easily available to consumers or waste products that could be given a second life.  In researching their options, the team (composed of Jack Richeson, Adam Dircz, and Brian LaQua) came across Tshabalala’s work on using wood in water filters, an arena he has been exploring for more than a decade.

FPL Research Chemist Mandla Tshabalala

FPL Research Chemist Mandla Tshabalala

Tshabalala met with the students and discussed the possibilities of wood for water filtration. He helped them consider various options for wood material, provided his research publications for background information, and showed them water filters he had designed, all the while encouraging the team to come up with a unique design and method of their own.

The students chose ponderosa pine bark as one of the filter media because it is readily available, cheap, and sustainable, and has been shown to remove copper and iron. Bark is a commonly available byproduct of timber processing mills; one FPL study estimates that the United States generates around 2.2 million metric tons of bark residues annually.

Along with pine bark, the winning filter employed sand and steel slag, a waste product of the steel industry. The design won first place by removing 83 percent of the contamination.

Filtered water samples.

Filtered water samples.

The UW-Madison Filter Team (l to r): Brian LaQua, Jack Richeson, and Adam Dircz.

The UW-Madison Filter Team (l to r): Brian LaQua, Jack Richeson, and Adam Dircz.

Jakes Honored with Early Career Scientist Award

FPL researcher Joseph Jakes has been selected to receive the 2011 Forest Service Research and Development Deputy Chief’s Early Career Scientist Award.

This award recognizes scientists who are at the beginning of their research careers and have demonstrated, through personal accomplishments, outstanding capability and exceptional promise for significant future achievement.

Jakes is a research materials engineer in FPL’s Performance Enhanced Biopolymers research unit. His research focuses on the use of nanoindentation to determine the structure–property relations of wood and wood-based materials at the sub-micrometer level. Jakes was selected for this award based on his research productivity, the impact of his work, and his efforts in science delivery.

As a recipient of the early career scientist award, Jakes is automatically nominated for the 2012 Presidential Early Career Awards for Scientists and Engineers competition, the highest honor bestowed by the U.S. Government on science and engineering professionals in the early stages of their independent research careers. These awards, established by President Clinton in 1996, are coordinated by the Office of Science and Technology Policy within the Executive Office of the President. Winning scientists and engineers receive a research grant for up to 5 years to further their study in support of critical government missions.

New Wood Product Launched with Help from FPL

With its more than 100 years of research on record, people often look to the FPL for answers when new questions about wood products arise. So FPL researchers were up to the challenge when Eastman Chemical Company approached them during the development of a new modified wood product.

In 2009, Eastman was developing a decking product by modifying Southern Pine through a chemical process called acetylation. Now marketed as Perennial Wood, the product has all the advantages of wood without its sensitivity to water.  Because the product is not traditional treated wood or a wood–plastic composite, however, developers were unsure about what types of adhesive would be most effective when needed.

Researchers at FPL have been studying how to bond wood products for decades. The expertise and equipment at the Lab, in addition to a history of successful public/private partnerships, made collaborating with Eastman a natural fit.

“Eastman was hoping to find an adhesive that was already on the market that would work well with their new product,” explains Chris Hunt, a research chemist at FPL. “So we worked with various adhesive suppliers, tested an array of formulas, and were able to make a recommendation for the most effective adhesive.”

Getting a solid answer to their question helped Eastman move their product into the marketplace.

“Research and testing conducted by FPL helped Eastman meet its goal of launching the complete Perennial Wood decking system at the same time,” said Ellen Turner, technical service and application development engineer for Perennial Wood. “Because modified wood is relatively new, we needed to test how various glues and adhesives would take to the wood. That’s where FPL was instrumental. Its research team identified the best alternative for bonding 1 by 4s together to create strong and crack-resistant railing posts, ensuring our products deliver the quality homeowners expect.”

According to Hunt, this partnership is a great example of government research benefiting the American public. “We were able to use our knowledge and facilities to assist a company that uses domestic materials and labor to create better products for the American public. FPL is here for the public, and partnerships like this showcase how our research works for you.”

Eastman Chemical Company, founded in Tennessee in 1920, is now a global producer of chemicals, fibers, and plastics that employs more than 10,000 people. Perennial Wood decking was officially launched in February 2012.