Tag Archives: cellulose nanofibres

Replacing metal with nanocellulose paper

Leave a reply

The quest to find uses for nanocellulose materials has taken a step forward with some work coming from the University of Maryland (US). From a July 24, 2015 news item on Nanowerk,

Researchers at the University of Maryland recently discovered that paper made of cellulose fibers is tougher and stronger the smaller the fibers get … . For a long time, engineers have sought a material that is both strong (resistant to non-recoverable deformation) and tough (tolerant of damage).

“Strength and toughness are often exclusive to each other,” said Teng Li, associate professor of mechanical engineering at UMD. “For example, a stronger material tends to be brittle, like cast iron or diamond.”

A July 23, 2015 University of Maryland news release, which originated the news item, provides details about the thinking which buttresses this research along with some details about the research itself,

The UMD team pursued the development of a strong and tough material by exploring the mechanical properties of cellulose, the most abundant renewable bio-resource on Earth. Researchers made papers with several sizes of cellulose fibers – all too small for the eye to see – ranging in size from about 30 micrometers to 10 nanometers. The paper made of 10-nanometer-thick fibers was 40 times tougher and 130 times stronger than regular notebook paper, which is made of cellulose fibers a thousand times larger.

“These findings could lead to a new class of high performance engineering materials that are both strong and tough, a Holy Grail in materials design,” said Li.

High performance yet lightweight cellulose-based materials might one day replace conventional structural materials (i.e. metals) in applications where weight is important. This could lead, for example, to more energy efficient and “green” vehicles. In addition, team members say, transparent cellulose nanopaper may become feasible as a functional substrate in flexible electronics, resulting in paper electronics, printable solar cells and flexible displays that could radically change many aspects of daily life.

Cellulose fibers can easily form many hydrogen bonds. Once broken, the hydrogen bonds can reform on their own—giving the material a ‘self-healing’ quality. The UMD discovered that the smaller the cellulose fibers, the more hydrogen bonds per square area. This means paper made of very small fibers can both hold together better and re-form more quickly, which is the key for cellulose nanopaper to be both strong and tough.

“It is helpful to know why cellulose nanopaper is both strong and tough, especially when the underlying reason is also applicable to many other materials,” said Liangbing Hu, assistant professor of materials science at UMD.

To confirm, the researchers tried a similar experiment using carbon nanotubes that were similar in size to the cellulose fibers. The carbon nanotubes had much weaker bonds holding them together, so under tension they did not hold together as well. Paper made of carbon nanotubes is weak, though individually nanotubes are arguably the strongest material ever made.

One possible future direction for the research is the improvement of the mechanical performance of carbon nanotube paper.

“Paper made of a network of carbon nanotubes is much weaker than expected,” said Li. “Indeed, it has been a grand challenge to translate the superb properties of carbon nanotubes at nanoscale to macroscale. Our research findings shed light on a viable approach to addressing this challenge and achieving carbon nanotube paper that is both strong and tough.”

Here’s a link to and a citation for the paper,

Anomalous scaling law of strength and toughness of cellulose nanopaper by Hongli Zhu, Shuze Zhu, Zheng Jia, Sepideh Parvinian, Yuanyuan Li, Oeyvind Vaaland, Liangbing Hu, and Teng Li. PNAS (Proceedings of the National Academy of Sciences) July 21, 2015 vol. 112 no. 29 doi: 10.1073/pnas.1502870112

This paper is behind a paywall.

There is a lot of research on applications for nanocellulose, everywhere it seems, except Canada, which at one time was a leader in the business of producing cellulose nanocrystals (CNC).

Here’s a sampling of some of my most recent posts on nanocellulose,

Nanocellulose as a biosensor (July 28, 2015)

Microscopy, Paper and Fibre Research Institute (Norway), and nanocellulose (July 8, 2015)

Nanocellulose markets report released (June 5, 2015; US market research)

New US platform for nanocellulose and occupational health and safety research (June 1, 2015; Note: As you find new applications, you need to concern yourself with occupational health and safety.)

‘Green’, flexible electronics with nanocellulose materials (May 26, 2015; research from China)

Treating municipal wastewater and dirty industry byproducts with nanocellulose-based filters (Dec. 23, 2014; research from Sweden)

Nanocellulose and an intensity of structural colour (June 16, 2014; research about replacing toxic pigments with structural colour from the UK)

I ask again, where are the Canadians? If anybody has an answer, please let me know.

The shorter, the better for cellulose nanofibres

Leave a reply

Cellulose nanomaterials can be derived from any number of plants. In Canada, we tend to think of our trees first but there are other sources such as cotton, bananas, hemp, carrots, and more.

In anticipation that cellulose nanofibres will become increasingly important constituents of various products and having noticed a resemblance to carbon nanotubes, scientists in Switzerland have investigated the possible toxicity issues according to a May 7, 2015 news item on Nanowerk,

Plant-based cellulose nanofibres do not pose a short-term health risk, especially short fibres, shows a study conducted in the context of National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64). But lung cells are less efficient in eliminating longer fibres.

Similar to carbon nanotubes that are used in cycling helmets and tennis rackets, cellulose nanofibres are extremely light while being extremely tear-resistant. But their production is significantly cheaper because they can be manufactured from plant waste of cotton or banana plants. “It is only a matter of time before they prevail on the market,” says Christoph Weder of the Adolphe Merkle Institute at the University of Fribourg [Switzerland].

A May 7, 2015 Swiss National Science Foundation (SNSF) press release, which originated the news item, provides more detail,

In the context of the National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64), he collaborated with the team of Barbara Rothen-Rutishauser to examine whether these plant-based nanofibres are harmful to the lungs when inhaled. The investigation does not rely on animal testing; instead the group of Rothen-Rutishauser developped a complex 3D lung cell system to simulate the surface of the lungs by using various human cell cultures in the test tube.

The shorter, the better

Their results (*) show that cellulose nanofibres are not harmful: the analysed lung cells showed no signs of acute stress or inflammation. But there were clear differences between short and long fibres: the lung cell system efficiently eliminated short fibres while longer fibres stayed on the cell surface.

“The testing only lasted two days because we cannot grow the cell cultures for longer,” explains Barbara Rothen-Rutishauser. For this reason, she adds, they cannot say if the longer fibre may have a negative impact on the lungs in the long term. Tests involving carbon nanotubes have shown that lung cells lose their equilibrium when they are faced with long tubes because they try to incorporate them into the cell to no avail. “This frustrated phagocytosis can trigger an inflammatory reaction,” says Rothen-Rutishauser. To avoid potential harm, she recommends that companies developing products with nanofibres use fibres that are short and pliable instead of long and rigid.

National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64)

The National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64) hopes to be able to bridge the gaps in our current knowledge on nanomaterials. Opportunities and risks for human health and the environment in relation to the manufacture, use and disposal of synthetic nanomaterials need to be better understood. The projects started their research work in December 2010.

I have a link to and a citation for the paper (Note: They use the term cellulose nanocrystals in the paper’s title),

Fate of Cellulose Nanocrystal Aerosols Deposited on the Lung Cell Surface In Vitro by Carola Endes, Silvana Mueller, Calum Kinnear, Dimitri Vanhecke, E. Johan Foster, Alke Petri-Fink, Christoph Weder, Martin J. D. Clift, and Barbara Rothen-Rutishauser. Biomacromolecules, 2015, 16 (4), pp 1267–1275 DOI: 10.1021/acs.biomac.5b00055 Publication Date (Web): March 19, 2015

Copyright © 2015 American Chemical Society

While tracking down the 2015 paper, I found this from 2011,

Investigating the Interaction of Cellulose Nanofibers Derived from Cotton with a Sophisticated 3D Human Lung Cell Coculture by Martin J. D. Clift, E. Johan Foster, Dimitri Vanhecke, Daniel Studer, Peter Wick, Peter Gehr, Barbara Rothen-Rutishauser, and Christoph Weder. Biomacromolecules, 2011, 12 (10), pp 3666–3673 DOI: 10.1021/bm200865j Publication Date (Web): August 16, 2011

Copyright © 2011 American Chemical Society

Both papers are behind a paywall.

Crystalline cellulose nanofibers and biomass fuel

Leave a reply

Perhaps one day the researchers who work with cellulose at the nanoscale will agree to some kind of terminology. Unfortunately, that day does not seem to be scheduled for the near future as per the latest research from Los Alamos National Laboratory and the Great Lakes Bioenergy Research Center (GLBRC) in the June 19, 2013 news item on ScienceDaily,

Improved methods for breaking down cellulose nanofibers are central to cost-effective biofuel production and the subject of new research from Los Alamos National Laboratory (LANL) and the Great Lakes Bioenergy Research Center (GLBRC). Scientists are investigating the unique properties of crystalline cellulose nanofibers to develop novel chemical pretreatments and designer enzymes for biofuel production from cellulosic — or non-food — plant derived biomass.

“Cellulose is laid out in plant cell walls as crystalline nanofibers, like steel reinforcements embedded in concrete columns,” says GLBRC’s Shishir Chundawat. “The key to cheaper biofuel production is to unravel these tightly packed nanofibers more efficiently into soluble sugars using fewer enzymes.”

The June 19, 2013 Los Alamos National Laboratory news release, which originated the news item, explains the new technique in more detail,

An article published this week in the Proceedings of the National Academy of Sciences suggests—counter-intuitively—that increased binding of enzymes to cellulose polymers doesn’t always lead to faster breakdown into simple sugars. In fact, Chundawat’s research team found that using novel biomass pretreatments to convert cellulose to a unique crystalline structure called cellulose III reduced native enzyme binding while increasing sugar yields by as much as five times.

…

The researchers had previously demonstrated that altering the crystal structure of native cellulose to cellulose III accelerates enzymatic deconstruction; however, the recent observation that cellulose III increased sugar yields with reduced levels of bound enzyme was unexpected. To explain this finding, Chundawat and a team of LANL researchers led by Gnana Gnanakaran and Anurag Sethi developed a mechanistic kinetic model indicating that the relationship between enzyme affinity for cellulose and catalytic efficiency is more complex than previously thought.

Cellulose III was found to have a less sticky surface that makes it harder for native enzymes to get stuck non-productively on it, unlike untreated cellulose surfaces. The model further predicts that the enhanced enzyme activity, despite reduced binding, is due to the relative ease with which enzymes are able to pull out individual cellulose III chains from the pretreated nanofiber surface and then break them apart into simple sugars.

“These findings are exciting because they may catalyze future development of novel engineered enzymes that are further tailored for conversion of cellulose III rich pretreated biomass to cheaper fuels and other useful compounds that are currently derived from non-renewable fossil fuels,” says Gnanakaran.

Here’s a link to and a citation for the published paper,

Increased enzyme binding to substrate is not necessary for more efficient cellulose hydrolysis by Dahai Gaoa, Shishir P. S. Chundawat, Anurag Sethic, Venkatesh Balana, S. Gnanakaranc, and Bruce E. Dalea. Published online before print June 19, 2013, doi: 10.1073/pnas.1213426110
PNAS June 19, 2013

There is open access to the article (I’m not sure if this is permanent or temporary).

As I hinted at the beginning of this piece, there are a number of terms used to describe cellulose at the nanoscale. For example, there’s nanocrystalline cellulose (NCC) which is also known as cellulose nanocrystals (CNC); this second term now seems to be preferred. My latest writing on nanocellulose, which seems to be a generic term covering all of the versions cellulose at the nanoscale is in a May 21, 2013 posting about some nanotoxicology studies and in a May 7, 2013 posting about a Saskatchewan-based (Canada) biorefinery (Blue Goose Biorefinery) and its production of CNC.

There are many more here on the topic and, if you’re interested, you may want to try CelluForce, FPInnovations, CNC, and/or NCC, as well as, nanocellulose or cellulose, as blog search terms.

The Swedes, sludge, and nanocellulose fibres

1 Reply

According to a Swedish research team at Luleå University of Technology, it’s possible to create cellulose nanofibres from sludge. Well, it’s a particular kind of sludge. From the Feb. 16, 2012 news item on Nanowerk,

For example, at one single cellulose manufacturer, Domsjö Fabrikerna in Sweden, the producer of special cellulose, which is used to in the manufacturing of viscose fibers, causes one thousand tons of sludge as a residue each year.

…

A few years ago, cellulose industries in Sweden, disposed some of their waste as sludge into the ocean. It is now prohibited, and the sludge is stored in large tanks on land. This particular cellulose sludge makes it possible, to produce, so far, the most profitable production of cellulose nanofibres from bio-residue products.

The yield of the manufacture of cellulose nanofibres from the sludge is 95%, compared with cellulose nanofiber production from wood chips 48%, lignin residues 48%, carrot residues of 20%, barley 14% and grass 13%. [emphases mine] “The separation of cellulose nanofibres from bioresidues is energy demanding but when we separate the waste from Domsjö, the energy consumption is lower. The special cellulose from Domsjö has very small size and it also has high cellulose content and therefore the fibers do not need to be chemically pre-treated before the production of cellulose nanofibers,” says Professor Kristiina Oksman.

This is interesting news especially in light of the interview with Jean Moreau (president of CelluForce, a company which manufactures nanocrystalline cellulose [NCC] in Québec, Canada) that I heard yesterday where there was some discussion as to what type of wood is needed to produce it.

In an interview with Dr. Richard Berry (now with CelluForce but with FPInnovations at the time), I asked where the NCC comes from (my Aug. 27, 2010 posting),

Q: Does the process use up the entire log or are parts of it left over? What happens to any leftover bits?

A:         We are starting from the bleached chemical pulp which is, to a large extent, cellulose. The left over bits have actually been processed as part of the chemical pulp mill processes. The acid used is recovered and reused and the sugars are converted into other products; in the demonstration plant they will be converted into biogas.

I’m not sure when the ‘spiderphone’  interview took place but it seems to be prior to the manufacturing/demonstration plant’s opening earlier this year (2012). For the curious, here’s a link to the 48 min. interview (roughly 25 mins. Moreau and roughly 25 mins. of questions from callers), http://ccc.spiderphone.com/RealCast/9597937293/Flashcast.html. (Thanks again to David Rougley for dropping by to leave a comment and this link to the interview on an earlier nanocellulose fibre posting [March 28, 2011].)

Getting back to the main event, the Swedish research is part of a larger project called Bio4Energy and you can find out more about that here.

Bravo to the Swedes for making use of sludge!