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Biomass Fundamentals Module 14 : Lignin II: Specialty Applications

Biomass Fundamentals Module 14 : Lignin II: Specialty Applications. A capstone course for BioSUCCEED : Bio products S ustainability: a U niversity C ooperative C enter of E xcellence in ED ucation. The USDA Higher Education Challenge Grants program gratefully acknowledged for support.

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Biomass Fundamentals Module 14 : Lignin II: Specialty Applications

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  1. Biomass FundamentalsModule 14: Lignin II:Specialty Applications A capstone course for BioSUCCEED: BioproductsSustainability: a University Cooperative Center of Excellence in EDucation The USDA Higher Education Challenge Grants program gratefully acknowledged for support

  2. This course would not be possible without support from: USDA Higher Education Challenge (HEC) Grants Program www.csrees.usda.gov/funding/rfas/hep_challenge.html

  3. What is “lignin?” • The amorphous glue that binds carbohydrate bundles • A complex, polydisperse (weight average MW/Number average MW  measure of distribution of individual MWs) polymer • A source of endless discussion for the exact nature of its biosynthesis in plants (enzyme controlled vs. random radical coupling) • C9 polypropylphenol derivative

  4. Lignin Biosynthesis

  5. Structures of Lignin Precursors

  6. Flavonoids: Chemical Offshoots of Lignin Biosynthesis • 15 carbon atom compounds (C6-C3-C6) – over 4000! • Polyphenol • Phytochemicals (phenolic acids, stilbenes, polyphenols) • Antioxidants • CV health: reduce agglomeration of platelets in endothelia • Assist lignification of cell walls in plants in response to injury • Antimicrobials

  7. Biologically Active Isoflavonoid • Rotenone comes from Derris root and Lonchocarpus species • Insecticide • Fish poison • Topical treatment of head lice, scabies, and ectoparasites

  8. Rheological Properties of Lignin • Schematic illustration of secondary cell wall of spruce tracheids • Between ordered cellulose fibrils is the lignin-hemicellulose matrix • Various vibrational studies (static & dynamic FT-IR) of lignin functional groups suggest lignin is ordered in plane with the plane of cell wall surface • Distribution, however, is not ISOTROPIC in fiber wall

  9. Rheological Properties of Lignin, Part Deux • Monolignols couple/polymerize under environmental constraints along fiber axis to ordered polysaccharide matrix • Polysaccharides templates*? • A high response in a 90° out-of-phase spectrum with lignin peaks indicates a more viscoelastic behavior for lignin over carbohydrates – also can move freely in matrix unperturbed by carbohydrates *

  10. Lignin in Composite/Industrial Applications • Lignosulfonates • Extrusion moldings • Fuel • Fertilizer/agricultural adjuvant • Potential raw material for fine chemical production

  11. Lignin as a Medical “Tissue” • Wood and bone possess unique structural motifs that fulfill requirements of support & transport of nutrients • Is it possible, therefore, to use wood as a implantable material? • Can it be used, for example, as a femoral replacement?

  12. Technical Hurdles to Address • Toxicity • Compatibility • Adsorption • Functionality • Mechanical Properties

  13. What is Bone? • Ceramic-polymer composite • Calcium phosphate (hydroxyapatite) and collagen • The apatite has different metal ions that adjust solubility and availability of mineral elements to rest of body • Small apatite platelets crystallize in preferred locations on collagen

  14. Ultrastructure of Bone

  15. Attempts to Mimic Bone • MOE: *Hydroxyapatite + polyethylene – middle ear implants, maxillofacial reconstruction, & bone repair; possesses MOE similar to bone • Porosity: Porites (coral species) have similar pore size & interconnectivity; CaCO3 (aragonite in coral)  hydroxyapatite by hydrothermal process • Hierarchical Structure: tendon, muscle, WOOD, and bamboo *

  16. van Leeuwenhoek’s Famous Comment When he first recognized the Haversian canals in bone in 1693, he made reference to other hierarchical structures:

  17. Structure & Function of Wood • Wood is a polymer of 20-30% lignin and the virtual remainder carbohydrates • Tracheid (osteocyte in bone) is “cell” • Tracheids consists of 5-30 nm wide microfibrillar elements composes of cellulosic strands (2.5 nm diameter) • Wood is porous and operates on negative pressure osmotic gradients in lumens and valves in pits – transport in bone is positive pressure from circulation of nutrients

  18. Morphological Structure of Juniperus communis A: annual rings; B: rays & pits; C: pirs in a ray connecting adjacent tracheid; D: Helical texture of spiraling cellulose strands outside a tracheid

  19. Bone & Wood • Collagen is bone’s counterpart to wood’s cellulose • Alternating fibrillar orientation in the various lamellae in bone and wood imparts strength & toughness • Pore networks differ only in size and connectivity

  20. Material Property Chart for Orthopedics

  21. Histological Section of Juniper Wood A: cortical bone after 3 mos. B: cortical bone after 6 mos. C: trabecular bone after 6 mos. D: Cortical bone after 1.5 years E: cortical bone after 3 years

  22. Conclusions from Medical Study • No infection, serendipitously due to wood oils • Boiling wood to remove excess oil and any microorganisms lowered MOE, better mechanical fit to wood (see chart) • Wood well tolerated by body – surrounded by bone • Even bone growth into open pores and artificial microchannels (a priori machining) for improved integration

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