New directions in forest-based composites: composite materials may lead the way for the next...

Editor's note: This article is the second of two-articles on forest-based materials. Part one appeared in the April 2002 issue of Solutions! The articles are part of a continuing series of report from the Forest, Wood and Paper Industry Technology Summit, held in May 2001 in Peachtree City,

Many forest-based products have become commodities and are under increasing threat from other media and products. In particular, the margins obtainable are producing unsustainable returns on capital. This situation challenges the industry to create new ways of making existing products, and to more clearly demonstrate their value.

The forest products industry is the largest producer of renewable, bio-based materials, but has not received the attention of basic science that other, more glamorous industries have received from government funded research at universities and national labs. However, recent developments in the area now known as "soft matter physics" show promising potential for our industry.

Importantly, new disciplines and funding can be brought to bear on our industry's problems and opportunities. The National Research Council's 1999 review of new directions for condensed matter physics found that natural cellulose products merit further funding

A diverse team of scientists and paper industry professional met at the Paper Summit to address these concerns. The team's vision was to identify the enabling technologies to make novel forest based products with a higher value to end users, based on a material science or physics approach. The team screened a number of making novel composites from wood components with other materials.

PROGRAM GOALS AND GAPS

The goal is to use forest based components with other materials such as minerals, polymers and biopolymers to make composite materials. Likely application areas include the construction industry, fabrics/clothing, lightweight furniture, packaging, automotive, coating materials, and "Super Paper."

The team identified six main properties as important and actionable:

* Strength--to increase by orders of magnitude over existing methods

* Surface properties--topography control; smoother and rougher

* Permeability/transport--control [O.sub.2] and [H.sub.2]O transport as well as thermal (phonon barrier)

* Optical--use well-defined building blocks to build in novel appearance properties

* Formability--the components must be capable of being formed into useful objects, and forming equipment developed

* Speed /quality--the composites must be made economically with good quality.

Before achieving these goals, the industry will need to address a number of gaps. These include:

* Building blocks

* Fibers (and fiber modification), minerals, polymers, biopolymers

* Nano-structures

* Self assembling systems

* Phage display and cloning

* Interracial science

* Organic

* Inorganic

* Bio-polymer

* Radically different biopolymer induced adhesion

* Protein

* Carbohydrate

* Processing (forming)

GAP FILLING TECHNOLOGIES AND RESEARCH AREAS

Building blocks: The key will be to identify the range and sources of building blocks needed to produce these new composites. We must rethink the properties needed and determine what this means for selected components. For example, we may need to access fiber types or minerals of different shapes and dimensions, as well as inorganic materials not used by the forest products industry today. Each would likely need modification for specific applications. The pulp and paper industry's strength is its considerable expertise in materials science.

Nano-structures: Developments in areas such as atomic force microscopy and its variants have allowed material scientists to see the world in a new way and understand bow to build materials from smaller scale building blocks. Many materials are made of components that are themselves a composite of many components and features that do not necessarily optimize the intended function. By using fundamental building blocks, it is possible to make materials with much higher performance than conventionally manufactured articles. For example, a new class of nano-composite materials has opened up that uses a very fine, well-dispersed bentonite type clay. The clay is an anchor point for long chain elastic polymers, and thereby enhances the performance and stability of the finished item.

The United States has a leadership role in nano-technology, and the government has started a funding program of about $500 million per year to maintain this position. Our industry can use techniques developed in this program to understand the building blocks in better ways and develop new uses.

Self-assembling systems: Colloid chemistry has reached the stage where researchers can identify systems to become ordered in well-defined structures based on the surfactants used. Examples abound in the worlds of block co-polymers, emulsions and membranes. Precise building blocks can be selected and organized into useful structures by using surface modifications or specialized surfactant additives.

Phage display and cloning: Macrophages or phages are viruses that attack bacteria and plant cells (see Fig. 1). They are comprised of DNA or RNA wrapped in protein. Phages have protein legs that have evolved to strongly bond to the bacterium cell wall to allow the phage to inject its DNA into the cell, take it over and replicate. Evolution has produced literally billions of variations of polypeptide sequences in phages, which can now be used to probe the surface to find the appropriate sequences needed for strong bonds.

[FIGURE 1 OMITTED]

Researchers can use existing phage libraries to identify the macrophages that bind strongly to a surface--for example, the 001 crystal face of' aragonite-which in turn allows them to identify the polypeptide sequence present that bonds specifically to the particular surface facet. Proteins have the advantage that amino acids come in variants that are acidic, basic, hydrophilic or hydrophobic. As a consequence, the bonding that takes place between a protein and a domain can be acid/base, hydrogen bonding or hydrophobic. The acid/base type bonds, in particular, are very strong and with the possibility of some hydrophobic character can produce adhesion stronger and more robust than the conventional hydrogen bonding seen in papermaking. Having identified the unique protein it is possible to clone it into Escherichia coli, for example, and produce more of it.

Interracial Science: Forest product based materials' performance depends on the way the components interact; this, in turn, is governed by the interracial energetics or compatibility. The key to creating composite materials is controlling the way the different components stick together. There are many techniques for characterizing surfaces in detail and understanding how to modify them. These range from infra-red, U-V visible through to photo-electron and atomic force microscopy, which allows one to visualize what happens on the surface. Researchers can model the interactions of a range of molecules on different surfaces and to predict the way that bonding will occur.

More importantly, it is now possible to use techniques developed in bio-technology to produce proteins or carbohydrates that will bond very specifically to a surface with a strength orders of magnitudes higher than possible conventionally. In addition, there have been developments in the identification of cellulose-binding domains to modify fibers and improve inter-fiber bonding strength. Laccases can also be used to add side chains to fibers.

MARKET DATA

Identifying market needs and wants is essential. At the very least, the industry must identify performance application areas, based on perceived needs. This must be done at a very high pre-competitive level, avoiding aspects closer to how the business would be run.

THE TEAM'S PROPOSAL

We propose to identify novel building blocks using techniques from nano-technology stuck together with chemistries identified from biotechnology to make composite materials. The basic concept is to use techniques from the world of biotechnology to develop proteins or carbohydrates that specifically bond to the surfaces of the selected building blocks in a way that provides at least an order of magnitude increase in strength. The selection of the building blocks will depend on the careful characterization and modification of components such as cellulose fibers, minerals and polymers.

The key steps are the use of phage display to identify the unique protein to act as the super-strong glue, and the subsequent cloning to make larger quantities.

TIMELINE

The Technology Summit team recommended that the industry form a "virtual center." Researchers will need time to review and digest existing information (12 to 18 months).

The initial steps would comprise the identification of a radically different biologically induced adhesion, identification of the required fiber type and modification, and development of self-organizing nano-structures to lead to a composite design. Team members expect that the production of a 50# sample of the new "adhesive" will take two years, including basic research and applications development.

CENTERS OF EXCELLENCE

The project will require a number of skills in the following areas:

* Wood/paper science

* Cotton chemistry

* Biotech

* Interfacial chemistry

* Polymer science

* Mineral/inorganic

* Applications

The research can take place in collaboration with expert facilities. Candidate "Centers of Excellence" are listed below by skill area. Biotech

* Univ. of California Santa Barbara (Biomimetics and AFM)

* University of Texas/Austin (Phage display and use)

* Small Biotech Firm

Nanostructures

* Renssalaer Polytechnic Institutes (Nano-structures)

* Sandia National Lab (Nano-composites)

Wood/Paper Science

* SUNY Syracuse (Fiber science)

* IPST (Paper science)

* Paprican (Wood and paper science)

Applications Development

* Forest Products Lab (Forest product based composites)

* MIT (Composites)

The initial development phase is probably best hosted "virtually" at IPST, where researchers can develop the skills needed to guide the program through identifying the needed proteins, surface chemistry and building blocks. In later scale up phases, research should move to the Forest Products Lab, which has experience in large scale manufacturing.

GREAT POTENTIAL

Developments in biotechnology will allow die production of proteins that will bond materials together more strongly than current systems. It is already feasible to produce fiber/fiber bonding stronger than we have today, allowing for the production of systems with at least orders of magnitude strength improvement. The Technology Summit team proposed that we use developments in biotechnology to develop composite materials based on paper products. Building blocks will be selected and modified using techniques developed in the world of nano-structures to allow the fabrication of novel functional materials.

The high performance composites will build on a renewable resource--cellulose. New products could include car parts, mobile phones, and even new materials for the runways of high fashion.

IN THIS ARTICLE. YOU WILL LEARN:

* Why composite materials are key to new uses for cellulose fibers

* How biotechnology can identify methods for stronger fiber bonding

* Which properties are most important when creating marketable composites

* The research directions identified for creating novel composite materials

ADDITIONAL RESOURCES:

* For Technology Summit information: www.tappi.org/ctosummit.asp

* The DOE and Forest Products Industry research:www.oit.doe.gov/forest/forest.shtml

* The National Resource Council: www.nationalacademies.org/nrc/

* "Forest Based Materials," Tom Amidon, Solutions! April 2002, p, 50.

Team Membership:

SCOTT CUNNINGHAM, DuPont Central Research & Development

ANDY GARNER, Paprican

TOM JEFFRIES, Forest Products Lab

PHIL JONES, Imerys

PAWEL KEBLINSKI, Renssalaer Polytechnic Intitute,

CHARLES MCDONALD, Dow Chemical

BANDARU RAMARAO, State University of New York

J. Philip Jones is vice president, technology for IMERYS, Roswell, Georgia, USA. Contact him by phone at +1 770 645/3373, or by e-mail at pjones@imerys.com