Unfortunately, the demand for wood products cannot be met even with the fastest growing trees. As the world population continues to grow, we must discover ways to produce the materials we need from renewable resources. The College of Natural Resources at Virginia Tech has been working on a process to enhance the strength and stiffness of low-density wood species using steam, heat, and mechanical compression. Heat and moisture can be used to manipulate the viscoelastic behavior.
Wood is also a porous material, being comprised of long slender cells.
About one-half the volume of wood is void space, but this varies widely by species and rate of tree growth. The strength and stiffness of wood is directly proportional to density. The VTC process increases the density of wood by softening the cell wall prior to compression in a mechanical device. We have also stumbled upon a phenomenon that increases strength and stiffness beyond what is expected from density increases alone. Although we don't completely understand what is happening, we believe the high temperature during the process chemically modifies the cell wall, resulting in the creation of additional covalent bonding at the molecular level.