Sappi, Edinburgh Napier University Discover Low-Cost Process to Make Nanocellulose

 

Scientists from Edinburgh Napier University, U.K., and Sappi, South Africa, have developed a low cost way to turn wood into a "wonder material" that could be used to build greener cars, thicken foods, and even treat wounds. The discovery means that Sappi will be able to produce the lightweight material on a commercially viable basis—and without producing large volumes of chemical wastewater associated with existing techniques. The energy-saving process will be used in a new nanocellulose producing pilot plant to be erected by Sappi. 

 

"Nanocellulose, extracted from wood fibers, has a number of unique optical, barrier, and strength properties," said project coordinator Math Jennekens, R&D director at Sappi Europe. "Unlike other lightweight, high-strength materials based on fossil fuels, it is completely sustainable, making it very desirable as a new material for various industrial and transport applications." 

The versatile material has previously been produced by intensively processing wood pulp to release ultra-small, or "nano" cellulose fibers—each so small that 2,000 could fit inside the width of a single strand of human hair. But the Edinburgh Napier research team says they have been able to drastically reduce the amount of energy needed to power the process, as well as the need for expensive chemicals.

 

"What is significant about our process is the use of unique chemistry, which has allowed us to very easily break down the wood pulp fibers into nanocellulose," said Professor Rob English, who led the research with his Edinburgh Napier colleague, Dr. Rhodri Williams.

"There is no expensive chemistry required and, most significantly, the chemicals used can be easily recycled and reused without generating large quantities of wastewater. It produces a dry powder that can be readily re-dispersed in water and leaves the nanocellulose unmodified—effectively making its surface a chemical "blank canvas" and so more easily combined with other materials. The ability to bring all of these attributes together have so far eluded materials scientists working in the field. It is very exciting," Professor English explains.

 

Nanocellulose produced at the proposed Sappi plant could be used in a wide range of industrial and everyday products and devices because of the way they can improve the properties of materials they are combined with, Professor English adds. "It could be used to thicken water-based products such as paints, foods, and concrete," he notes. "Or when it’s used in plastics to make a composite, it can replace glass fibers, which is very attractive in the production of the next generation of lighter, fuel-efficient vehicles.  

"Because of its low oxygen permeability it could also be a possible replacement for plastic films in packaging. Then there also are applications for it in containing films in lithium batteries and touch screen displays. And as cellulose is inherently bio-compatible and bio-absorbable, there is considerable potential in biomedical applications such as wound dressings and regenerative medicine," Professor English continues. 

Andrea Rossi, Group Head Technology, Sappi Ltd., says that a pilot production plant is being planned for "towards the end of 2015. This pilot plant," he points out, "will move Sappi into new adjacent business fields based on renewable raw materials to produce innovative performance materials and help in delivering on Sappi's strategy to seek growth opportunities in adjacent and new markets."

Professor English adds that "commercial interest in nanocellulose is growing at a phenomenal rate following predictions of a possible 35 million metric tpy per year market by the 2020s. And so the key challenge now is very much in business development and understanding the value offered by nanocellulose in our target markets."

According to Rossi, the pilot plant will test the manufacturing of dry, re-dispersible Cellulose NanoFibrils (CNF). Using this proprietary breakthrough technology, Sappi will ultimately be able to manufacture CNF with unique morphology, specifically modified for either hydrophobic or hydrophilic applications. Products produced will be optimally suitable for conversion in lighter and stronger fiber-reinforced composites and plastics, in food and pharmaceutical applications and rheology modifiers, as well as in barrier and other paper and coating applications.

Rossi indicated that using the products manufactured in the pilot-scale plant, Sappi will seek co-development with multiple partners to incorporate CNF into a large variety of product applications to optimize performance and to create unique characteristics.