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Nanotechnology Applications in the Forest Products Industry by Robert J Nanotechnology Applications in the Forest Products Industry By Robert J. Moon, Charles R. Frihart, and Theodore Wegner The National Nanotechnology Initiative (NNI) was has grown to 12 and 25, respectively.1 The vision of the NNI established in 2001 to coordinate the R&D of nanoscale sci­ is a future in which the ability to understand and control ence, engineering, and technology across the federal gov­ matter at the nanoscale level leads to a revolution in tech­ ernment. The Nanoscale Science, Engineering and nology and industry. The four goals of NNI are to 1) maintain Technology Subcommittee coordinates in the NNI and oper­ a world-class R&D program aimed at realizing the full poten­ ates under the auspices of the National Science and tial of nanotechnology; 2) facilitate transfer of new tech­ Technology Council. In its first year, NNI was composed of nologies into products for economic growth, jobs, and other six agencies investing in nanotechnology. Since that time, public benefits; 3) support responsible development of nan­ the annual federal investment has more than doubled in otechnology; and 4) develop educational resources, a nanotechnology R&D to approximately $1.3 billion, while skilled workforce, and the supporting infrastructure and the number of funding and participating federal agencies tools to advance nanotechnology. In addition, the NNI is 4 MAY 2006 developing a national infrastructure that will provide access products industry to include paper, composites, and solid­ to user centers that house expensive and sophisticated sawnlumber.Specifically,thealliancehasidentifiedsixmajor equipment that is necessary but not cost effective for any areas of technological needs: 1) advancing the forest biorefin­ one group or institution to purchase and maintain. The NNI ery; 2) positively impacting the environment; 3) developing is also establishing research centers that will each have a the next generation fiber recovery and utilization; 4) creating specific focus and expertise that can be called upon as breakthrough manufacturing technologies, 5) advancing the needed to solve narrow but complex problems. wood products revolution; and 6) developing a technological­ ly advanced workforce. The Alliance recently adopted nan­ otechnology as a focus area and is developing a technology Forest Products roadmap for research in this area. In fiscal year 2006, the USDA Forest Service has initiat­ Nanotechnology Research Agenda ed the following research programs: 1) use the intrinsic nanoscale properties of wood and similar lignocellulosic Although wood has unmatched aesthetic qualities, the materials for developing advanced nanomaterials; 2) use most important attribute of wood is its mechanical proper­ nanoprocesses to modify lignocellulosic materials; and 3) ties. These properties are important whether the forest prod­ use nanometrology techniques to investigate the funda­ uct is solid wood, a composite, an engineered wood product, mental structure of materials, the ways in which they a corrugated container, or a sheet of paper. continued R&D on degrade, and methods for inhibiting this degradation. In forest products is essential for product property improve­ fiscal year 2007, the USDA Forest Service will place addi­ ments that wiil meet future needs and provide products at rea­ tional emphasis on these programs using internal and sonable costs. Nanotechnology R&D is critically important to external resources. Scientists will investigate areas of fun­ the economical and sustainable production of new genera­ damental nanoscale phenomena and processes, nanoma­ tions of forest-based materisal and to help move society terials, nanoscale devices and systems, instrumentation, toward a biomass-based economy. Nanotechnology offers the metrology, and standards for nanotechnology. potential to transform the forest products industry in virtual­ NanotechnologyR&DattheUSDAForestService,Forest ly all aspects, ranging from production of raw materials, to Products Laboratory (FPL) has five focus areas for basic new approaches for productin engineering wood and wood- research: 1) analytical methods for nanostructure character­ based materials, to new applications for composite and paper ization: 2) cell wall nanostructures; 3) nanotechnology in products, to new generations of functional nanoscale lignocel­ sensors, processing, and processing control; 4) polymer lulosics.2 Other potential uses for nanotechnology include composites nad nanoreinforced materials; and 5) self- developing intelligent wood- and paper-based products with assembly and biomimetics. The remainder of this article an array of nanosensors built in to measure forces, loads, describes in detail one nanotechnology R&D area of interest moisture levels, temperature, pressure, chemical emissions, as an example of research that FPL will be exploring. This and attack by wood decay fungi. Building functionality onto basic research utilizes sub-micrometer mechanical property lignocellulosic surfaces at the nanoscale could open new characterization (via nanoindentation) and structure-prop­ opportunities for such things as pharmaceutical products, erty modeling to investigate nanoscale chemical and self-sterilizingsurfaces,andelectroniclignocellulosicdevices. mechanical interactions between the basic polymers of Nanotechnology can be used to improve processing of wood- wood (cellulose, hemicellulose, and lignin). The outcome of such research will assist in the understanding of wood’s based materials into products by improving water removal and eliminating rewetting; reducing energy usage in drying; mechanical and chemical properties and allow for improved and tagging fibers, flakes, and particles to allow customized mechanical performance of wood, adhesive joints, swelling/shrinking behavior, and other attributes. By under­ property enhancement in processing. standing how nature works its magic, we may be able to use Advancing the forest products nanotechnology research genetic, biological, or chemical changes to design wood agenda requires cooperation between the forest products and nanotechnology research communities, the federal depart­ products rather than just using what nature has provided. ments and agencies thathave ongoing programs in nanotech­ nology R&D, and the NNI.1 The forest products industry has a goal to establish a nanotechnology R&D program under the NNI that would have an annual budget of $40 million to $60 million. To focus the R&D efforts, a consensus on research needs and priorities among forest products industry, acade­ mia, and government is needed. The forest prducts iondustry can build upon established and successful programs such as the Americqan Forest & Paper Association’s Agenda 2020 ResearchAlliance.ThisAllianceisanindustry-ledpartnership with government and academia for collaborative,pre-compet­ itive research, development, and deployment. It has devel­ oped an industry-wide research agenda for the entire forest Figure 1. – Research and development activities by 1 www.nano.gov categorical group, 2003. Source: National 2 www.nanotechforest.org ScienceFoundation. FOREST PRODUCTS JOURNAL VOL. 55, NO. 5 5 Figure 2. – Schematic showing the general sequence of indentation: a) indenter tip makes contact with sample surface; b) is pressed into the sample surface; and c) is retracted from the surface, having a permanent indent. Using Nanoindentation for some surface properties (chemistry, reactivity). However, only nanoindentation allows the measurement of mechanical Basic Wood Research properties. In the following sections we describe what nanoin­ dentation techniques actually determine, how they can be Structure of Wood applied to wood, and what we can learn from them. The most important attribute of wood is its mechanical properties, in particular its unusual ability to provide high Nanoindentation Techniques mechanical strength and high strength-to-weight rationwhile Mechanical properties of materials have been common­ allowing for flexibility to counter large dimensional changes ly characterized using indentation techniques because of the due to swelling and shrinking. These unique properties of ease and speed of conducting the tests. The basic premise of wood are a direct result of its hierarchical internal struc­ all indentation techniques is that a hard material of specified ture. The structure of wood spans many length scales (see shape (indenter) is pressed into the surface of a softer mate­ cover illustration): meters for describing the whole tree, rial (substrate) with sufficient force that the softer material centimeters for describing structures within the tree cross deforms (Fig. 2). Properties that are measured by indentation section (pith, heartwood, sapwood, and bark), millimeters describe the deformation of the volume of material beneath for describing growth rings (earlywood, latewood), tens of the indenter (interaction volume). Deformation can be by micrometers for describing the cellular anatomy, microme­ several modes: elasticity, viscoealasticity, plasticity, creep, ters for describing the layer structure within cell walls, tens and fracture. These deformation modes are described by the of nanometers for describing the configuration of cellulose following properties, respectively: elastic modulus, relax­ fibrils in a matrix of hemicellulose and lignin, and nanome­ ation modulus, hardness, creep rate, and fracture toughness, ters for describing the molecular structures of cellulose, Characterizing these properties provides a method
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