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EvaluTree — a New Resource for the Pulp and Paper Industry in Canada

The initiative for this new state-of-the-art facility for wood and fibre analysis grew from a need identified in the late 1990s and the early 2000s to link wood and fibre quality to end-use products. ...

May 1, 2007  By Pulp & Paper Canada

The initiative for this new state-of-the-art facility for wood and fibre analysis grew from a need identified in the late 1990s and the early 2000s to link wood and fibre quality to end-use products. Paprican’s Fibre Supply and Quality program indicated that a significant opportunity existed for optimizing fibre use and maximizing the value from Canada’s fibre resource by linking wood and fibre quality to performance in both production processes and products. The limiting factor, however, was the cost of assessing wood quality on a sufficiently large scale for statistically valid results. Traditional techniques to measure wood quality are too time-consuming. In order to address this problem, the concept of EvaluTree was created under the leadership of Dr. Paul Watson (formerly Paprican’s Fibre Supply and Quality program manager). This world-class facility is now operational and fully-equipped with state-of-the-art technologies that provide comprehensive wood and fibre analysis solutions.

What is EvaluTree’s primary mandate?

EvaluTree will act as a resource for collaborative research and high-throughput testing services for the forest industry. As a CFI-funded research group, our mandate is to help researchers better understand the wood quality issues impacting Canadian mills. As a Paprican business unit, our responsibility is to provide low cost analyses internally for FPInnovations research programs, and externally for the forest products industry.


What instrumentation does EvaluTree have?

EvaluTree has a suite of instruments to evaluate both the physical and chemical properties of wood and wood fibre. The advanced diagnostic equipment includes: ion chromatography and spectroscopy for wood chemistry, advanced imaging tools such as an environmental scanning electron microscope (ESEM), a confocal laser scanning microscope (CLSM) and a Hi-Res Fibre Quality Analyser (FQA) for fibre analysis. EvaluTree’s show piece is SilviScan, an award-winning technology specifically designed to rapidly assess wood quality characteristics, including fibre dimensions, wood density, microfibril angle, and modulus of elasticity.

How does the latest ESEM improve the analysis of pulp and paper quality?

Our new field-emission environmental scanning electron microscope (ESEM) is one of the most versatile instruments in the EvaluTree suite. Its advantage over SEM comes from its ability to operate with moisture vapour (“environment”) in the chamber.

Consequently, the need for dry samples and conductive coatings is eliminated. This provides several benefits:

* Faster sample preparation

* Direct imaging of the sample: no coating obfuscating the results

* Non-destructive imaging

The instrument is made even more versatile by a range of accessories. These include:

* a cooling stage (0.1 from ambient temperature to -20C)

* a heating stage up to 1000C

* a 200N tensile stage for in-situ tensile testing

* detectors enabling secondary electron imaging under all environments.

Using the ESEM mode in combination with its cooling facility, it is possible to control the specimen temperature and the chamber pressure to target specific levels of relative humidity ranging from 0 to 100%. Thus, dynamic experiments can be conducted in which the moisture content in the sample is varied. An example application is illustrated in Fig. A, showing the changes in moisture content of a newsprint sample subjected to three cycles of wetting and drying. This simulates a three-unit printing process, and thereby provides new insight to researchers on the performace of paper in printing presses.

Another use of the ESEM has been in the study of laboratory-made nanocrystalline cellulose (Fig. B). The instrument’s high-resolution capability for imaging both coated and uncoated samples makes it ideal for this purpose.

What are the applications of confocal and multi-photon microscopy in pulp and paper research?

Light microscopy is an important technique for analyzing wood and fibre morphologies as well as paper structure. Confocal Laser Scanning Microscopy (CLSM) is the latest significant advancement in light microscopy. It has the amazing ability, known as optical sectioning, to rapidly and nondestructively generate two- and three-dimensional (3D) images of thick specimens in-situ with micron-level resolution. This optical sectioning capability avoids the need for mechanical sectioning and tedious sample preparation that is required for conventional optical microscopy.

EvaluTree has recently added a state-of-the-art confocal laser scanning microscope to its facility. The new system has a wide range of lasers and detectors that allow simultaneous visualization of sample components based on their characteristic fluorescent emissions. In addition, the new microscope has the capability of multi-photon microscopy, the latest technology in two- and three-dimensional CLSM imaging that can image deeper into samples, such as paper, than previously possible with conventional CLSM.

The powerful features of this new microscope are expected to broaden applications of CLSM in wood, pulp and paper analysis. As an example, the new system enables researchers to rapidly generate cross-sectional images of paper structure with various components clearly identified. EvaluTree researchers are currently using these techniques to view the interactions between coatings, fillers, sheet structure and ink deposition. The level of observable detail is illustrated in Fig. C, which shows a cross-sectional image of a sheet with fibres and fillers. The sample was prepared simply by cutting the paper edge with a razor blade. The CLSM is currently being used to assess the results of trials by Paprican member companies on the performance of their papers.

How are spectrometric tools improving wood chemistry analysis?

In addition to traditional wood chemistry analysis, EvaluTree is using a combination of spectroscopy and chemometrics to build models that can rapidly predict chemical properties from solid wood increment cores.

Our spectroscopy capabilities include Fourier-transform infrared (FT-IR), Fourier-transform near infrared (FT-NIR), dispersive near infrared (NIR), FT-IR microscopy, dispersive Raman and FT-Raman (Fig. D). These technologies complement the traditional wet chemistry methods and are applied to perform rapid wood chemistry predictions within an acceptible degree of error and to reduce the time, and hence the cost of analyses.

Infrared absorption is a direct process involving infrared radiation penetrating into the surface layer of the particles, exciting the vibrational modes of the analyte molecule, and then scattering in all directions. The reflected or transmitted radiation is detected and plotted to produce a spectrum that is unique to the sample. In Raman spectroscopy, a laser photon of well-defined energy is scattered off a molecule and some energy is lost to molecular vibrations. The difference between the laser energy and that of the scattered photons is detected. The differences, called Raman shifts, are plotted to produce a spectrum.

The interpretation of large spectroscopic data sets is best performed using chemometrics, a chemical discipline that uses mathematical and statistical methods to obtain the most information from chemical data. With such statistical software, correlations can be made between spectra and the results of traditional wood chemistry.

What is SilviScan and what does it measure?

SilviScan is a key component of EvaluTree (Fig. E). It is a suite of instruments designed for the rapid and non-destructive assessment of wood and fibre properties on a pith-to-bark wood core sample extracted from a standing tree or a log. This Marcus Wallenberg prize-winning system is one of o
nly three in the world, and was developed in Australia by the Commonwealth Scientific and Industrial Research Organization (CSIRO) Forestry and Forest Products Division. The other two instruments are located in Australia and at STFI in Sweden.

SilviScan consists of a combination of analytical technologies, including optical microscopy, x-ray diffractometry, x-ray densitometry and image analysis. Together, these give key information on the many wood fibre properties that govern product quality and production efficiency. Examples of the properties determined are: fibre diameter, fibre wall thickness, wood density, fibre coarseness, microfibril angle (MFA), and wood stiffness.

EvaluTree’s focus in the near future will be to integrate the information produced by SilviScan with information obtained from other instruments. As this process is completed, we will be able to widen the assessment of Canadian fibre and feed this information into value-chain modeling, thereby completing the link between Canada’s fibre resource and products from the forest industry.

What are some examples of EvaluTree at work?

Examples of EvaluTree at work are the University of Laval’s Arborea project and Paprican’s studies of the mountain pine beetle’s effects on wood quality. The first study is a collaboration between Genome Quebec, the University of Laval, Canadian Forest Service, University of Alberta, Ministre des Resources Naturelles, de la Faune et des Parcs, Agriculture and Agri-Food Canada, University of Georgia and Paprican. It’s aim is to discover the natural genes that are responsible for wood quality and growth traits in white spruce. EvaluTree’s role in this project is to quantify the phenotypic variation, in particular qualities that are commercially valuable in the plantation spruce populations under study.

Paprican’s mountain pine beetle research, funded by the Canadian Forest Service’s Mountain Pine Beetle Initiative, is aimed at determining the impact of the beetle attack on pulp quality. As a business unit, EvaluTree contributes to the project by performing the wood and fibre quality analysis for Paprican’s researchers. As an example of this contribution, in one spectroscopy-based study, a model was developed that predicts the degree of blue stain, decay (caustic solubility), moisture content and density in mountain pine beetle (MPB) killed wood from measurments obtained with a portable NIR device.

In two other studies funded by the Canadian Forest Service, SilviScan was used to determine other impacts of beetle infestation. In the first, on the shelf life of MPB-killed trees in British Columbia, it was found that although wood moisture decreased dramatically, the wood and fibre properties measured by SilviScan were not significantly affected by time-since-death of the trees. The second study evaluated the impact increasing pine content has on pulp quality of spruce-pine-fir mixtures. It was found that the influence on pulp quality from increasing pine content was minor.

Looking to the future, what role do you see for EvaluTree?

In coming years, EvaluTree will play an integral role in meeting a key objective of FPInnovations, set out by its president Dr. Ian de la Roche, in the March issue of Pulp & Paper Canada, as “.. to develop and apply technolgies that will enable us to extract maximum value from Canadian fibre.” This will be accomplished by supporting the ongoing research in the various divisions of FPInnovations, performing services for member companies and governments, and interacting with the academic community. Of particular importance in the next few years will be EvaluTree’s contribution to the tranformative technologies initiative. This initiative will focus on technologies that bring major change to Canada’s forest industry. It will include research on topics such as advanced paper and wood products, nanotechnology, biochemicals, and bioenergy. Clearly, a detailed knowledge of the physical and chemical attributes of Canada’s forest resource will be a key component of many apsects of this research. EvaluTree will play an integral role in obtaining this information.

For more information, please contact Andrew Goodison (agoodison@paprican.ca) of the FPInnovations — Paprican Fibre Supply and Quality program.

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