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OBJECTIVES AND GOALS: The primary goal of this proposed research is to integrate the production of high-value nano-fibrillated cellulose reinforcement for polymers as a biofuel co-product using recalcitrant cellulose from enzymatic hydrolysis process. Woody biomass will be converted into both monosaccharides for the production of infrastructure-compatible biofuels and highly refined nanocellulose for polymer reinforcement. <P>
The specific objectives for this research are to: <OL> <LI> Investigate the relationship between enzymatic hydrolysis conditions, sugar yield, viability of the hydrolysate as a biofuel, and properties of nano-fibrillated cellulose, including degree of polymerization, crystallinity and mechanical performance <LI> Optimize processing, such as drying cycles and fiber orientation, of nano-fibrillated cellulose to maximize reinforcing potential <LI> Evaluate the reinforcement efficiency of nano-fibrillated cellulose in polymer composites and the composition-process-structure-property relationship of the resulting materials </ol> OUTPUTS: The primary output is knowledge-base that aids in the development of high-value nanocellulose co-products in the biorefinery process. This knowledge will be disseminated through peer-review publications, technical conference proceedings, etc. Tangible composite materials will also be produced and likely used as display and public outreach materials. <P>
MILESTONES: <BR> YEAR 1: <ul> <LI> Nanocellulose (NC) will be prepared using initial conditions (e.g., commercial enzymes and bleached kraft pulp (BKP))<LI> First round of design, synthesis and testing of endocellulases (thermostable and basidiomycetous) using E. coli expression <LI> Prepare randomly oriented mats; begin investigation for continuous fiber production; begin to develop methods for dispersing NC in thermoplastic </ul>YEAR 2: <ul><LI> Complete fractionation study using model recycle pulp and commercial enzymes <LI> Evaluate best endocellulase candidates for improved expression and modifications. First round in design, synthesis and testing of exocellulases, glucosidases, and auxiliary enzymes. <LI> Investigate methods for aligning NC during mat preparation; <LI> Develop lay-up & impregnation methods to produce composites from various reinforcements; continue continuous fiber production investigations <LI> Disperse NC in thermoplastic </ul>
YEAR 3: <UL> <LI> Complete fractionation using commercial enzymes <LI> Make adjustments in expression and purifications to produce all enzymes, as isolated proteins, and as defined mixes, on a scale suitable to test nanofiber-sugar production characteristics <LI> Further investigate continuous fiber production. Initial evaluation of NC in supercritical fluid (SCF)-assisted injection molding</ul> YEAR 4:<UL> <LI> Complete the feasibility study using selected custom enzyme at high solids<LI> Test suitability of sugar stream to make HAF - Evaluate NC reinforcements made from BKP using commercial enzymes with optimized conditions and composite processing techniques </ul> YEAR 5: <UL> <LI> Evaluate lignocellulosic feedstocks <LI> Make improvements based year 4 results <LI> Evaluate reinforcements from NC made using newly developed enzymes with optimized conditions and composite processing techniques <LI> Write final report
NON-TECHNICAL SUMMARY: The production of fuels from renewable cellulosic materials, including trees, is technically possible, but barriers, especially economic ones, prevent this possibility from becoming a reality. However, the economics could be made favorable by developing high-value co-products, along with fuel production. One of the strategies for converting biomass, such as agricultural waste and trees, to fuel involves breaking down the cellulose, which is a carbohydrate, into sugars that can then be converted to other chemicals including transportation fuels. Much of the cellulose, however, proves difficult to breakdown into sugars using practical methods, and this recalcitrant cellulose often presents problems in the biorefinery process. Instead of finding methods to further breakdown the recalcitrant cellulose, we propose to find value in it. Previous research has shown that cellulose broken down into the nanometer scale has unique properties, including high strength. However, the full potential of this nanocellulose has yet to be realized. Our work intends to investigate how to integrate the production of biofuels with nanocellulose and how to exploit the nanocellulose such that its potential can be realized. For example, we plan to investigate methods of converting the nanocellulose into forms that can be made into composites using processes that are employed in the automotive and aerospace industries. By understanding the optimal conditions for producing both biofuels and nanocellulose, as well as demonstrating practical, high-value use for nanocellulose, we expect our research to bring the biorefinery concept closer to reality.
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APPROACH: In the proposed research, the less recalcitrant amorphous cellulose will be saccharified using cellulase enzymes, and the hydrolysate will be converted to a biofuel intermediate. The remaining recalcitrant cellulose (RC) will be processed into nanocellulose using high-shear homogenization. Reinforcements will be produced from the resulting nano-fibrillated cellulose, and various processes including drying, orienting and forming will be examined to enhance their mechanical properties and their reinforcing efficiency. These reinforcements will then be incorporated into both thermoset and thermoplastic polymers. The activities of this research project are organized into integrated, complimentary stages and tasks. The first stage consists of the process of converting the woody biomass to products including sugars, fuels (or fuel intermediates) and cellulosic nanofibers, and the second stage consists of converting the cellulose nanofibers into reinforcements and incorporating those into composites. The characteristics of the materials produced in the first stage are likely to have a direct impact on the properties of the reinforcements and composites. As the research progresses, correlation among various properties of the materials and the resulting products will be assessed. Attempts will be made to optimize both the production of sugars for fuel production and the quality of nanofiber reinforcements. The relationships between hydrolysis conditions and product properties will be recorded and reported. Many of the characterizations and procedures performed will be done using standard methodologies, but some of the experiments will require unique procedures and modifications to equipment. For instance, the high-solids enzymatic hydrolysis will be conducted in a laboratory 1 L bowl mixer developed and housed at FPL. Methods and procedures for constraining, orienting and forming nanofiber mats, as well as those for forming continuous fiber reinforcements, will also have to be developed. In all cases, the Forest Products Laboratory Research Quality Management Program will be followed, and documentation of the procedures, setups, equipment, etc. will be documented. Publications and technical presentations of the results and methodologies will be provided. As warranted, appropriate procedures regarding intellectual property and technology transfer will be followed with an emphasis on attracting commercial interest for the production of cellulose nanofiber as a biorefinery co-product and as reinforcements for composites.