Pulp and Paper 1b PDF

Wood = 93% virgin fibre of the world = Principal source of fibre for pulp + paper. 7% Non-wood sources = Bamboo, Bagasse, Cereal straw, Cotton, Linen, Jute, Hemp, Abaca and Sisal + Synthetic fibre sources Cell wall = Cellulose + Other Support Polymers. Polymer chemistry = Specialise the simple cell...

Wood = 93% virgin fibre of the world = Principal source of fibre for pulp + paper. 7% Non-wood sources = Bamboo, Bagasse, Cereal straw, Cotton, Linen, Jute, Hemp, Abaca and Sisal + Synthetic fibre sources Cell wall = Cellulose + Other Support Polymers. Polymer chemistry = Specialise the simple cell structure = Xylem, Phloem, Collenchyma, Sclerenchyma, Parenchyma etc Softwood = Cornifers/Gymnosperms = needle leafed. Hardwood = Deciduous or Evergreen/Angiosperms = broad leafed Average Composition of Softwood and Hardwood Hardwood Softwood ~42% Cellulose = Long chain ~45% molecules with no branching. Mainly skeletal polysaccharides. ~27% Hemicellulose = Branched ~30% short chain molecules. Mainly matrix polysaccharides. ~28% Lignin = Three dimensional ~20% phenolic polymer network. ~3% Extractives = Extraneous ~5% substances are easily extracted by neutral organic solvents (benzene, ether, alcohol, acetone) or isolated with steam. Includes, terpenes, resins, fatty acids, phenols, unsaponifiables etc. Softwood vs. Hardwoods (spruce vs birch) Average f ibre length sof twood mm hardwood Age f rom pith yrs Chemistry of the Plant Cell Structure and Collective Composition of Wood Cellulose, Hemicellulose, Cellulosans, Lignin, Pectin, Resins, Waxes, Fatty or fixed oils, Cyclitols, Tannins, Mucilage, Alkaloids Matured woody plant = percentage of each component is skewed more towards Cellulose, Hemicellulose and Lignin Components vary between different woody plants.  Wood Cell wall substances = insoluble Extractives/Extraneous substances = in neutral organic solvents or non- Extracted with neutral organic solvents volatile with steam. or isolated with steam. (benzene, ether, alcohol, acetone etc.) Wood 21% in Hardwoods 25% in Sof twood 2-8% Extractives = Terpenes, Lignin Resins, Fatty acids, Phenols etc Carbohydrates 35% = hardwoods 45% 25% = softwoods Cellulose = Hemicellulose = glucose glucose, mannose, galactose, xylose arabinose Cellulose = (C6H10O5)n Polysaccharide = Repeating units of D-glucose = joined by 1,4’-b- glycosidic linkages. Chains = exclusively linear = arrangement of monomer encourages many intra and intermolecular interactions = Structural polysaccharide of plants Amorphous region Macrof ibril easily penetrated by Crystalline solvents and reagents regions Impenetrable by solvents and other reagents.  O H C H OH Fischer projections CH 2OH D-Glyceraldehyde O H CHO C Haworth projections H OH H OH Cyclic forms more CH2 OH CH2 OH H HO H HO H predominant H O OH H H OH H OH O O H OH H OH CH 2 OH H2 C OH D-glucose pyranose rings D-Glucose Cis = b OH CH 2OH H CH 2OH H Trans =  H OH mutarotation HO O O HO O HO OH HO OH OH H OH H OH H OHH OH b-D-glucosepyranose b-D-glucosepyranose ring -D-glucosepyranose ring OH H H O HO H HO H H OHOH -D-glucosepyranose  O O- H + OH O R1 H + R2 H R1 H R1 H R2 O H R2 O Carbonyl Alcohol Hemiacetal H+ R3 H O OR 3 OH 2 H 3O + + R1 H R1 H R2 O R2 O Acetal  OH OH Starch/Glycogen = 6 6' 4 H 4' 1,4'--glycosidic linkages HO 5 O O 5' O 1 O 1' O Encourages branching and HO 3 2 H HO 3' 2' H OH OH coiling b-D-glucopyranose rings -H 2 O 1,4'- b-glycosidic bond formation Individual molecules of cellulose are stif f like rods. Equatorially placed glucose residues OH OH reduce the total energy of the entire molecule and encourages stability. HO O O HO O O OH HO H OH Extensive H-bonding networks hold the individual rods or fibres together n to form microfibrils which have high Cellobiose = tensile strength = concrete = van der waals disaccharide repeats itself