BY RAMONA DU HOUX

December 11, 2011
The University of Maine’s Forest Bioproducts Research Institute (FBRI) is building a pilot-scale plant for manufacturing cellulose nanofibrils (CNF), a wood-based reinforcing material that is increasingly of interest to researchers worldwide looking for super-strong materials that could replicate synthetic plastics.

“With development of new natural and functional nanomaterials, UMaine will be recognized as an innovator in novel cellulose nanofibril processing,” said FBRI Director and UMaine Professor of Chemical and Biological Engineering Hemant Pendse. “UMaine will have the ability to process cellulose nanofibrils in ways that open up applications for cellulose nanocomposites. It will be at a scale that opens up markets.”

Last April UMaine, with scientists from six other educational institutions and the Forest Products Laboratory (FPL), began a research collaboration on the conversion of wood components into novel nanomaterials.

The pilot plant, which is being funded by a $1.5 million grant from the U.S. Forest Service, is the only one of its kind in the nation and will serve as a source of the material for those who want to explore the uses of cellulose nanofibrils (CNF). Until now researchers and industrial companies who want to buy the material purchase it from sources in Japan and Germany.

“If you can make products from nanofibrillated cellulose that normally use plastic, you can reduce the use of petroleum,” said Doug Bousfield, UMaine professor of chemical and biological engineering. “What this project does is put the equipment in place to generate a lot of raw material with which people can experiment. It’s exciting — a natural fit for UMaine.”

The grant will fund the purchase of an ultrafine grinder (a piece of equipment which breaks down cellulose-based pulp into a water-based slurry) and a pilot-scale spray dryer, which uses gases to dry the material. The ultrafine grinder will be able to produce about 1,000 pounds of material a day in slurry form.

Applications for the CNF material include automobile components, paint and coating additives, and water filters. Development and commercialization have been hampered by the lack of availability of CNF material in sufficient quantities to conduct meaningful technology demonstrations. This project will address this need by scaling up the mechanical laboratory preparation method to a pilot-scale operation.

Cellulose nanofibril material is valued because of its strength — a strand of it is as strong as a synthetic fiber such as Kevlar. It takes on different properties depending on how it is dried. When a sample of the CNF slurry is dried with heat, the material becomes hard and strong, and can be cut into different shapes and sizes. When freeze-dried, the material is super-absorbent and insulating.

The cellulose nanofibrils are about 1,000 times smaller than paper fibers. The material can be made from any source that contains cellulose, such as wood, grasses, and corn or wheat straw.

UMaine already produces some cellulose nanofibrils via both mechanical means and chemical means, the latter of which produces cellulose nanocrystals.

Doug Gardner, a UMaine professor who is also a collaborator and the head of the Nanocomposites Research Group, said although the mechanisms are not yet in place for researchers and companies to order the material, there has already been unofficial interest from private industry. The material would not be free for those who want to order it, but UMaine would offer it at a reasonable price.

UMaine will be the sole supplier of CNF to researchers.