U.S. Department of Agriculture (USDA) scientists have a plan for using a U.S. cotton production byproduct to make biobased interior wood adhesives. The byproduct, cottonseed meal, is the leftovers after lint and oil are extracted from cotton seed. The meal is typically fed to ruminant livestock, such as cows, or used as fertilizer.
Most such adhesives are derived from petroleum, a nonrenewable resource subject to fluctuating prices and many competing demands, notes Zhongqi He, a chemist with the Agricultural Research Service (ARS), USDA’s principal intramural scientific research agency.
Cottonseed meal and its protein component have been studied as environmentally friendly, biodegradable and formaldehyde-free alternatives to petroleum-based bonding agents. But, to date, neither the seed meal nor the protein has been commercially developed into biobased adhesive products, according to He, who is with the ARS Southern Regional Research Center’s Commodity Utilization Research Unit in New Orleans, Louisiana.
Defatted seed meal is inexpensive but adhesives made from it have poor water resistance. Although the meal’s protein component works better as a wood-binding adhesive, extracting the protein requires using costly and corrosive reagents and solvents. Now, He and colleagues may have a solution in the form of a seed-meal washing process that potentially improves water resistance. In tests with maple and poplar veneers, the bonding strength of water-washed seed-meal adhesives equaled and sometimes surpassed that of protein-only formulations.
He and ARS chemist Dorselyn Chapital and their colleagues have reported their findings in recent issues of the Journal of the American Oil Chemists’ Society and the International Journal of Adhesion and Adhesives.
More research and development for wood adhesives from the washed cottonseed meal could usher in a new, value-added use for the more than 1 million tons of this byproduct. Biobased wood adhesives are appealing on several fronts, including the potential for improved indoor air quality for workers who make them and for consumers who use the products for interior wood-working applications.
Read more about this research in the June 2015 issue of AgResearch magazine.