Role of Anatomy in paper manufacturing

Role of Anatomy in Paper Manufacturing: 

Role of Anatomy in Paper Manufacturing Presented By: Saba Riaz Roll No. 354 ( M.phil Botany) GC University, Lahore

Anatomy role in Paper making: 

Anatomy role in Paper making The anatomy of various woods is important for the characteristics of papermaking fiber depend much upon their anatomy, specie and growth condition. Populus species were not used commercially until it was realized that they had good papermaking qualities. About two-thirds of the commercial species have appreciable use in pulp and paper making. Even, red gum, Liquidamber styraciflua , were cosidered to be as weed tree before 1900.

Antomical history of plants in paper production: 

Antomical history of plants in paper production As the research development have been taken place, the different families of plants have been identified Softwood families Pineaceae Cupressaceae Taxodiaceae Taxaceae Araucariaceae Podocarpaceae Hardwood families Casurnaceae Protaceae Santalaceae Erythoxylaceae Zygophyllaceae Rutaceae Rubiaceae Onchnaceae Meliaceae

Anatomical Selection of fiber: 

Anatomical Selection of fiber Due to anatomy and research, the following factors identified and more plants become source for paper production Fiber length, structure and number Cross-sectional shape Fiber thickness Cell wall chemistry Flexibility The manner in which cells are joined Tensile strength Weight factor Fiber pitting

Fiber Tissue: 

Fiber Tissue In a strict anatomical sense, xylary fibers are the elongated supporting cells of the ground tissue with thin and thick lignified walls and simple of distinctly bordered pits. Fiber include a variety of cell types. Paper is manufactured from the secondary xylem of both softwood (gymnosperms) and hardwood ( dicotyledons ) species.

Fiber length, number and structure: 

Fiber length, number and structure Anatomical features prove that fiber strength, length and bonding all interrelate to determine tear strength. The longer the fiber, the higher will be the tear strength. Most papermaking softwood fibers range in length from 3.0 to 5.0 mm . The more diverse hardwood fibers range between 0.7 to 2.5mm . Fast growing trees with long fibers and low lignin contents are ideal for pulp and paper making.

Thickness of Fiber: 

Thickness of Fiber Anatomy proved that Thick walled fibers form paper with a low tensile strength but a high degree of resistance to tear. Have a low folding endurance. They fewer inter-fiber bonds Cell wall thickness of fiber relates to whether the fiber lumen has collapsed during processing to form a ribbon-like fiber, or whether it remains open. Flexible and thin walled fiber with collapsed lumens yield high quality papers

Weight Factor of Fiber: 

Weight Factor of Fiber Parham and Gray 1990 indentified that the number of fiber is manipulated by its weight factors. The higher the relative surface area (per given mass of pulp) , the lower the weight factor. The weight factor for most hardwood are 0.40 and for the softwood is 0.35 . Fiber Pitting Pulp operations and refining are also dependent upon the way pits are arranged in a fiber. Intervessel pitting is present in hardwood. Ray cross-field pitting is present in softwood.

Four Types of Cellulose Fibers: 

Four Types of Cellulose Fibers Wood Fibers Seed Hair Fibers Cotton fibers Bast Fibers Flax plant Only 5% of the flax plant is usable for paper manufacturing Grass Fibers Wheat straw Bagasse fiber (extracted from sugar cane stalks) Esparto grass Kenaf plant

PowerPoint Presentation: 

1. Wood Fibers We divide the types of trees used in making paper into two categories: Hardwood species Softwood species Hardwood trees such as oaks and maples have wood with very short fibers. Softwood trees such as pine and spruce have wood with long fibers. 95% of all paper is made from wood fibers.

Role of Softwood: 

Role of Softwood Pulp made from softwoods is rather homogeneous and Composed of long trachieds . Softwood generally produce coarse, strong pulps Paper made from this type of wood is much stronger, but usually the finish is a bit rougher as compared to hardwood. Softwood gives more tensile strength.

Role of Hardwood: 

Role of Hardwood Pulp derived from hardwood species is heterogeneous Composed of wide vessel elements as well as narrow, elongate, thick walled cells that are true fibers in the strict histological sense. Hardwood pulps results in finer, smoother papers. Paper made from these species is weaker than that made from softwoods, but its surface is smoother, and therefore better to write and print on.

PowerPoint Presentation: 

There are two broad categories of cells in mature wood: Prosenchyma Parenchyma In hardwood pulp the parenchyma cells are often selectively removed with fines during processing. Because of their small size they do not contribute to paper strength but they contribute appreciably to low freeness in pulp. Fibres from hardwood gives opacity .

Tension Wood and Gelatinous Fiber: 

Tension Wood and Gelatinous Fiber The tension wood of many, but not all, hardwood is characterized by the gelatinous fiber. Paper made from tension wood are poorer in strength Because tension fiber’ gelatinous fiber has more cellulose content and are usually deficient in bonding properties. E.g dicotyledons

Soft wood: 

Soft wood Hard wood

2. Seed Hair Fibers—Cotton Plant: 

2. Seed Hair Fibers—Cotton Plant Cotton fibers are very expensive . Used primarily for bank notes, high grade writing papers, maps—anything that requires exceptional strength and durability.

3. Bast Fibers; non woody crops: 

3. Bast Fibers; non woody crops Obtained from the phloem of the dicots , flax plant. Fiber may obtain from the pericycle and cortex. Fiber can be obtain from the vascular tissues of leaves e.g sisal Hemp and jute are bast examples Barley; Rice, Espato, Triticum sp, Bamboo, Sugar cane.

4. Grass Fibers: Naturally Growing Plants: 

4. Grass Fibers: Naturally Growing Plants Useful fiber is derived from the vascular tissues of monocot Absorbs water readily. Was used during World War II in England due to a severe shortage of pulpwood. Have long fibers and elongated cells as in angiosperms Fiber can reach approximately 10 cm in length.

Grass Fibers (continued): 

Grass Fibers (continued) Kenaf plant May produce 5 to 7 times more pulp/acre than pine. Grows to maturity in 120 days compared to 20 years for most trees . The fibers used are of dark color near the edge of the stem consisting of phloem and other tissues.

Paper recycling: 

Paper recycling Process of turning waste paper into new paper products. There are three categories of paper that can be used as feed stocks for making recycled paper: Mill broke Pre-consumer waste, and Post-consumer waste.

PowerPoint Presentation: 

Mill broke is paper trimmings and other paper scrap from the manufacture of paper, and is recycled internally in a paper mill. Pre-consumer waste is material which left the paper mill but was discarded before it was ready for consumer use. Post-consumer waste is material discarded after consumer use, such as old corrugated containers , old magazines, old newspapers , office paper, old telephone directories, and residential mixed paper.

Advantages of Recycling of paper: 

Advantages of Recycling of paper Recycling one ton of newsprint saves about 1 ton of wood while recycling 1 ton of printing or copier paper saves slightly more than 2 tons of wood. Energy consumption is reduced by recycling 40% reduction in energy when paper is recycled versus paper made with unrecycled pulp

References: 

References William C. Dickison : Book of Integrative Plant Anatomy ; page no. 392-402. Chritopher . J. Biermann ; Hand book of pulping and papermaking; second edition; page no. 516 to 639.