(Blacksburg, Va., April 8, 2002) -- The big trees are gone or protected. So wood composites -- from fast growing trees such as pine or poplar -- fill the need for wood as an affordable, versatile construction material. The adhesive, which can impart durability and strength, is critical to the usefulness of wood composites.
Virginia Tech researchers are examining the variabilities of polymeric isocyanate, a new adhesive that is favored because of its rapid cure, and superior performance. They will present their research at the 223rd national meeting of the American Chemical Society, April 7-11 in Orlando.
"We are trying to learn the fundamental chemistry of polymeric isocyanate as it cures with wood," says Charles Frazier, professor of wood science and forest products at Virginia Tech. " We want to control the properties, particularly durability."
Polymeric isocyanate has many advantages. It cures rapidly, increases wood's strength and stiffness, and reduces undesirable swelling caused by moisture. Also, its chemistry does not include formaldehyde, so there are no formaldehyde emissions from the final product. Although it is an oil-based adhesive, it is still enviornmentally efficient, since it makes up less than 8 percent of the final composite product, and often less than 3 percent.
However, polymeric isocyanate performs differently with different kinds of wood. "Manufacturers are being faced with performance variations beyond their control," says Frazier. "We are studying the morphology of the resin with different woods and the cure chemistry with the aim of achieving adhesive performance on a par with the best regardless of the type of wood in the composite."
The talk, "Wood species dependence of isocyanate resin performance," (Cell 46) will be presented by Frazier on Monday, April 8, at 2 p.m. in Convention Center room 311D, level three. Co authors are wood science and forest products graduate students S. Das, M. Malmberg, and postdoctoral research associate X. Zhou.
The research is funded by the USDA National Research Initiative.