Fibrous raw materials for paper- making made by- Maulik chitransh himanshu bansal1Pulp and Fibers In the paper making process pulp is the fibrous mass made of cellulose.To a papermaker, fiber refers to elongated or tubular, slender and actually very small cell obtained from certain plants or plant parts.

2sources of fibers3Types of fibersPulp fibers can be extracted from almost any vascular plant found in nature but a high yield is necessary if the plant is to have economic importance.Wood by far is the most abundant source of fibers. Except for seed hair, vegetable matrix are embedded in a matrix of non fibrous material(mostly lignin with hemicellulose gum and resin)

Synthetic fibersPlant fibersAnimal fibers4Plant fibersSeed Hair FibersCotton fibersBast FibersFlax plantOnly 5% of the flax plant is usable for paper manufacturing

Grass FibersWheat strawBagasse fiber (extracted from sugar cane stalks)Esparto grassKenaf plantWood Fibers

5Seed Hair FibersCotton PlantCotton fibers are very expensive.Used primarily for bank notes, high grade writing papers, mapsanything that requires exceptional strength and durability.

6Bast FibersObtained from the flax plant.Located inside the stem.Only 5% usable for papermaking.Hemp and jute are other forms of bast fibers.Hemp has been used for cigarette and Bible papers.Jute obtained from new burlap cuttings or other sourcesIt is used for heavy duty shipping tags and heavy pattern boards.

7Grass FibersWheat StrawAbsorbs water readily.Was used during World War II in England due to a severe shortage of pulpwood.Bagasse fiberMade from crushed stalks of sugar cane.Used as a source of fuel for Sugar Mills.Esparto PlantHas very little strength and does not split into fibrils easily.Impractical for use in the United States because of the distance from the source of supply.Kenaf plantShows great potential for papermaking.May produce 5 to 7 times more pulp/acre than pine.Grows to maturity in 120 days compared to 20 years for most trees.

8Wood Fibers95% of all paper is made from wood fibers.Deciduous hardwood trees, e.g., Oak, Gum, Maple, Aspen, etc.Coniferous softwood trees, e.g., Pine, Spruce, Fir, etc. (the softwoods produce a stronger pulp).

9Animal fibersAnimal fibers like wool cannot be used for paper making. They cater to the needs of textile industry.In medieval era people used to write on parchment and vellum which were made from animal skins.

10Synthetic fibersMain reason to use synthetic fiber such as HDPE or LLDPE(polythene) or PP(polypropylene) is to provide the paper special performance properties such as tearing strength, dimensional stability in wet state, security features etc. End uses include paper for food packaging e.g. tea , coffee etc.Even the cheapest man-made fiber rayon cost 3-6 times normal wood pulp fibers.

11Fiber chemistry12Cellulose Cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to over ten thousand (14) linked D-glucose units.The recurring glucose anhydride unit is called cellobiose unit. Where the molecule fit together over long segments, regions of crystallinity develop which are difficult to penetrate by solvent or reagents. Properties of cellulose directly dependant to degree of polymerization . Decreasing the molecular weight below a limit will deteriorate strength.

Hemi-celluloseLong chain cellulose are called alpha cellulose. A number of shorter chain polysaccharides are collectively known as hemicelluloses.Hemicelluloses are classified as :Beta glucose- DP between 15 to 90.Gamma glucose- DP less than 15.Hemicelluloses are polymer of five different sugars hexoses (glucose, mannose and galactose) and pentose (xylose and arabinose).The hemicelluloses are easily degraded and dissolved so that their percentage is always less in the pulp.

Lignin The term holocellulose is used to define the total carbohydrate(cellulose + hemicellulose) content of fibers.In addition woody plant material contains a highly polymerized amorphous substance called lignin whose principle role is to form the middle lamella(the outer layer of the fiber) which cements fibers together.Structure contains primarily of phenyl propane units linked in 3-D. The 3 linkages between benzene rings are broken during chemical pulping operations to free cellulosic fibers.

15Fiber charecteristics and quality16Fiber characteristics and product qualityThe original physical attributes of fibers largely determine their suitability for further processing and the ultimate quality of finished paper. Quality of pulp is determined largely by the source of fibers and different pulping techniques.Fiber morphology concerns with the shape and size and the fiber wall architecture which determines the characteristics and properties of the end product.

Fiber characteristics:-1 flexibility2 plasticity3 resistance to mechanical processing4 inter-fiber bonding5 structural features as average length, diameter , wall thickness and wall ultra structure.6 content of cellulose hemi-cellulose and lignin7 conformable, strong bonding and stable.17Properties of fiber(continued)Fiber length: usually it is believed that a paper made from a long fiber will give more strength however using different types of raw material, good quality paper can be made from short fibers too. Fiber length influences general structure and surface properties of a paper. cell wall thickness: the pulps obtained from wood having thin walled fibers give dense and well bonded sheets and those thick walled give bulky sheets with high tear resistance. It is apparent that thin walled cells collapse and conform to give a dense bonded sheet of paper, due to high flexibility.Coarseness: it depends largely on fiber wall thickness. It is defined in weight in milligrams of fibers needed to give 100 meter length. 18Cell wall ultrastructure The fibers are built up of several different layers and has cavity inside.The internal organization of fiber wall , the percentage chemical present in it and its dimensions are very important features in deciding the pulp and paper making characteristics of fibers.The internal organization is referred to as ultrastructure.The organic materials are the polymers discussed earlier which with special arrangement produces a complex and highly ordered material with distinct structural and mechanical properties. 19Reference to1 Handbook for pulp and paper technology by G.A. Smook2 pulp and paper chemistry and chemical technology volume 1 by J.P. Casey20Thank you21