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27 Cards in this Set
- Front
- Back
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____ a complex biological material primarily composes of cellulose, hemicellulose, lignin, and small amounts of extractives and inorganic materials.
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Woods |
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• Understanding these basic components crucial for various applications, Including ___, ____, and the ___ |
construction, paper manufacturing and production of bio based materials. |
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Primary components of wood |
a. Total Polysaccharide fraction-Haincel ulice 160-70%)
b. lignin 15-355 |
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Secondary components |
a. Tannins b. Volatile oils and resins Gums, Latex, alkaloids, dyes etc. d. Ash 1 |
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a. Total Polysaccharide fraction-Haincel ulice 160-70%) |
1. Cellulose (40-50%)2. Hemicellulose (20-35%) |
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Most abundant macro molecule (and carbohydrate)
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Cellulose |
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The primary structural component of wood
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Cellulose |
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It is a polysaccharide consisting of long chains of glucose Units Inked by B-14-glycosidic bonds.
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Cellulose |
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• Vields glucose upon complete hydrolysis. Partisi hydrolysis yields cellobiose.
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Cellulose |
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•These chains alion parallel to each other to form microfibrils, which are the fundamental structural elements of cellulose
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Cellulose |
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___ imparts strength, rigidity, and high tensile strength to wood, making it resistant to breaking under tension |
Cellulose |
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Cotton fiax: about ___% cellulose
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97-99 |
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Wood: about ___ cellulose |
50% |
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Vegetable: about __ percent |
33 |
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Nandigestible by humans
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cellulose |
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• food for herbivorous animals (e.g., cows, horses): termites also digest cellulose
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cellulose |
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Of great economic importance, ___ is processed to produce papers and fibres |
cellulose |
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• Functions as supporting material in the cell wall.•
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Hemicellulose |
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A complex and high molecular weight polymer built upon phenylpropane units.
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Lignin |
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Functions of Lignin
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1. Serves as a cementing substance that binds wood cells together. 2. Imparts stiffness and rigidity to the cell wall. 3. Increases toxicity of wood to microbiological agents of decay. |
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Types of Lignin:
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Guaiacyl - one methoxyl group (conifers or softwood) Syringyl - two methoxyl group (hardwood) para-hydroxylphenyl - without methoxyl group |
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Often seen as tethering molecules that cross link cellulose microfibrils.• |
Hemicellulose |
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Usually account for up to 20 and 30% of dry weight of wood.• |
Hemicellulose |
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Heterogeneous polysaccharides that have beta-(1-- >4)-linked backbones of glucose, mannose, or xylose linked in equatorial configuration. |
Hemicellulose |
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- one methoxyl group (conifers or softwood)
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Guaiacyl |
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- two methoxyl group (hardwood)
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Syringyl |
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- without methoxyl group |
para-hydroxylphenyl |
