Cellulose materials patentedBy Susan Trulove
Spectrum Volume 18 Issue 33 - June 13, 1996
Ten years ago, Akzo, a major multinational chemical company based in The Netherlands, told Virginia Tech wood chemist Wolfgang Glasser that unless rayon fiber can be processed more like polyester fiber, "there won't be any rayon in the future," recalls Glasser.
Rayon, which is made from wood pulp, "is a very high value-added material as far as products from trees are concerned," he explains. Its continuance is important to the forest industry.
Akzo America funded research to explore how the wood product cellulose might be processed into fibers using technology common to the less expensive polyester fibers-that is, out of melt instead of out of solutions, "which are very polluting"; be made to feel like cotton, which customers prefer for its moisture-absorbing capacity, without the loss-of-shape disadvantage of cotton; and preserve its biodegradability.
A patent being issued June 4 for "Cellulose derivatives with a low degree of substitution," is a result of that research project. Glasser, post-doctoral student Gamini Samaranayake, and master's degree student James E. Sealey II demonstrated that the three goals can be met with very little chemical modification of the cellulose material.
"It can be done," says Glasser. "We did define the molecular conditions needed to achieve the three characteristics Akzo sought; however it is not cost effective." At least not at this time for such products as clothing and diapers.
"But where cost is not a factor, such as in health care, these modifications are attractive," he says. And not just for making bandages, but for creating artificial skin, membranes for kidney dialysis machines, even applications in HIV drugs, Glasser says.
"Cellulose is the most abundant polymer in the world." And because of Akzo's early investment in research at Virginia Tech, Glasser and his students and colleagues have been at the cutting edge of developments leading to new technology for cleaner processing and new high value-added products from cellulose.
Ten years ago, on the advice of one of the world's leading researchers on polymers, James E. McGrath, a member of the National Academy of Engineering and a chemistry professor at Virginia Tech, Glasser began to explore applications with then newly discovered solvents that could change cellulose. Using the same principles that underlie the June 4 patent, Glasser has adapted the chemistry of cellulose so that it can be used to "grab" specific components from fluids, such as medically necessary proteins out of blood or milk, to be processed into pharmaceuticals. Patents jointly developed with Virginia Tech chemical engineer William H. Velander have already been issued and licensed on such products.
Now the Deutsche Forschungs-gemeinschaft (DFG, the equivalent of the U.S. National Science Foundation) has launched a priority research program on cellulose and cellulose derivatives, with a focus on the design of molecular and supramolecular structures. Glasser helped judge the proposals for the six-year program (1996-2002), and more than 30 projects are being funded.
Many of the program's researchers will be featured speakers at a symposium being organized by T.J. Heinze of the University of Jena and Glasser at the American Chemical Society's national meeting in Orlando, Fla., August 25-29.
Meanwhile, the research has been a valuable educational experience to Glasser's research partners. Samaranayake, who is from Sri Lanka, earned his doctorate in natural products chemistry and received patents for his work on taxol with Virginia Tech chemistry professor David Kingston. Samaranayake now works at Westvaco on the chemistry of lignin, also a major component of wood. Sealey, who is from Deltaville, Va., is now a Ph.D. student at the Institute of Paper Science at Georgia Tech.