Fibers & Wood

Wood Next to food crops, perhaps human-kind’s most important plant product. Used for housing, furniture, paper, fuel (wood & charcoal), and raw materials for synthetics (rayon, cellophane, cellulose acetate) Forests covered ca. 1/3 of Earth’s land surface. Ca. 50% of original forest gone. Current rate of deforestation > rate of reforestation (especially in tropics; where used mostly for fuel & land for crops/ranching). U.S. & Canada leading producers of wood & wood products (including paper) (In U.S, mostly from pines & firs in SE & NW).

Wood, cont. Mostly cellulose & lignin from secondary cell walls; mostly vessels and/or tracheids and fibers. From secondary xylem – most cells are impregnated with lignin and are dead. Hardwoods - angiosperms –wood mostly vessels + some tracheids Softwoods - gymnosperms –wood mostly tracheids, more uniform

Cell structure Cell wall : primary: 9-25% cellulose, microfibrils, hemicelluloses (20-50%), pectic substances (10- 35%), and proteins (10%). Primary cell walls have a high tensile strength and are porous Middle lamella : pectin –Glue holding cells together Secondary cell wall: 45% cellulose, 30% hemicellulose and 22-28% lignin

Wood products Includes: Paper, Veneers, Plywood, Particle board, Charcoal, Resins & oils (pitch, turpentine), Cork

Biological Properties: Xylem Conducts water and minerals from soil upward –gymnosperms Tracheids “Softwoods; e.g., pine, spruce, cedar, fir, hemlock –angiosperms Tracheids Vessel elements Hardwoods; e.g., maple, oak, mahogany, poplar, walnut, ash, hickory

Fig a

Stems: Secondary growth Vascular tissue, (xylem) makes up the bulk of the stem Forms tree rings

Wood characteristics Porosity - manner in which large vessels are dispersed, only in hardwoods. Diffuse or ring-porous wood. Grain - alignment of xylem cells. Knots - Inclusion of branch in xylem.

Sapwood: functional xylem next to cambium Heartwood: older non-functional (for transport) xylem cells (still functions in support); best for solid wood

Physical Properties of Wood Tensile Strength Compression Strength Splitting Strength

Cork Characteristics due to many air-filled cells, good insulating material, lightweight, floats Cork cambium develops within the secondary phloem Quercus suber - cork oak

What is paper? Paper derives from the word "papyrus“. Paper includes a wide range of products with very different applications: communication, cultural, educational, artistic, hygienic, sanitary, as well as storage and transport of all kinds of goods. It's almost impossible to imagine a life without paper. The best paper is pure cellulose (lignin is undesirable).

Paper trivia Each American uses about 144 pounds of paper per year! More than 500,000 trees per week are used to produce the 2/3 of newspapers that are never recycled. Every ton of paper that is recycled saves 17 trees, 7,000 gallons of water, & 4,100 kilowatts of electricity. Producing paper from recycled fibers reduces air pollutants by as much as 74% and water pollutants by as much as 35%. Paper making is one of the most polluting of industries. Ca. 50% of harvestable wood in industrial nations goes to paper making.

Historical writing surfaces papyrus (Cyperus papyrus; Cyperaceae) – from Egyptians, ca years ago, learned by Greeks & Romans rice paper (Fatsia papyrifera, Araliaceae) - Orient mulberry paper (Broussonetia papyrifera, Moaraceae) – Mayans Also, non-plant substances; e.g., parchment, clay

Paper separated plant fibers that have been matted together to form a sheet can come from various sources (e.g., straw, rags), but wood most common alternate sources being considered include hemp (Cannabis sativa) and kenaf (Hibiscus cannibinus)- these make better paper (lower lignin) true paper (origin from China, second century) –thin sheets must be made from fiber (vessel, tracheid, fiber) that has been macerated until each individual filament is a separate unit –fibers are then intermixed with water, and, by the use of a sieve like screen, are lifted from the water in the form of a thin stratum, the water draining through the small openings of the screen leaving a sheet of matted fiber upon the screen's surface –this thin layer of intertwined fiber is paper

Making Paper Harvesting Cooking with lye Rinsing Beating or blend to make pulp –Add laundry starch to size Mould and Deckle

Bamboo Over 1000 diverse species from across globe; in Grass family. No secondary xylem, primary growth only. Segmented, hollow tubes, typical grass stem (woody culm produced from rhizome). Many many uses: e.g., fishing poles, caning for furniture, house construction in tropics, skyscraper scaffolding in Japan, paper making in India. Pandas feed on young leaves & stems of bamboo. Bamboos have unusual life cycle: some species grow for decades without flowering, then all the members of a species worldwide will flower and die the same year.

Plant Fibers & Their Uses Chapter 18, Table 18.1, pg 288 Chapter 18, Table 18.A, pg 298

Historical perspective Plant fibers have been used throughout human history, initially as strips of bark, stems, or leaves to make mats, baskets, etc. Wild cotton used for spinning and twining is traceable to Peru 12,000 ybp. Flax has been used for 8000 years, so plant fibers were apparently used in weaving before animal fibers.

cellulose plant fibers are composed of cellulose - long chain of glucose molecules animal fibers are protein (collagen)

Properties of cellulose Withstand high temperature Does not incorporate colors easily Resistant to animal pests, but susceptible to fungi and termites Less elastic than animal fibers and have higher affinity for water

Most synthetic fibers are produced from petroleum Nylon, polyester, etc. Exception is rayon

Plant fibers that are short, brittle, or slippery cannot be twined, woven, plaited, or spun can be used for paper, fiberboard, cellophane, and rayon (synthetic “silk” made from cellulose, mostly from wood pulp)

Fibers must stand up to twisting in spinning process, which holds the fibers together mechanically Surface fibers – from seeds, leaves, fruits (mostly hairs) Bast (soft) fibers - phloem tissues (mostly fibers) of dicots Hard (leaf) fibers – vascular bundles (xylem, phloem, fibers) leaves of monocots

Fiber characteristics Look and feel Strength Elasticity Density Resistance to heat, chemicals, sun, etc.

Fiber extraction Retting - produces bast fibers –plant stems placed in water or wet area to rot –thick-walled xylem remains and must be removed by scutching –fibers are hackled (separated and aligned) by drawing them across a comb Ginning - seed fibers –fibers are removed from seed

Cotton: Seed & Fruit Fibers Most important fiber plant. Easily processed mechanically. Fibers dye well and withstand vigorous washing. Origins 10-12,000 ybp in New World, 5000 ybp in Old World. Tremendous influence on history; especially U.S. history. Top producers: China, U.S., India, Egypt,…

Cotton species Member of Mallow family; shrubby perennial. Needs warm climate and lots of water. Fibers from seed hairs (e.g., 20,000 per seed); seeds packaged in a capsule (cotton boll). Hairs are 90% cellulose. Four main species grown: –Gossypium hirsutum and G. barbadense (New World; tetraploids, N=52) (G. hirsutum = 95% of world production; upland cotton) (G. barbadense = pima, Egyptian cotton) –G. arboreum & G. herbaceum (Old World; diploids)

Cottons perennials, but are grown as annuals tremendous amount of pesticides are used in cotton culture plants are defoliated chemically and machine harvested Eli Whitney's invention of cotton gin led to explosion of cultivation of cotton in U.S. and increased need for slaves to work fields

Cotton Processing Ginning - removal of seeds and debris Carding - fibers are combed parallel to produce a web Sliver - made by twisting web into a large rope Drawing - more alignment Spinning Cleaning - boiled in caustic soda and bleached

Cotton processing II Mercerization - stretched and placed in cold caustic soda, increases luster, dye uptake and durability. Sizing - stiffening agent (e.g., starch) before weaving. Permanent press - chemicals used to cross- link polymers.

Bast: Flax Linum usitatissimum – linen and linseed oil. Annual from Flax family. May be oldest plant fiber used for cloth (> 10,000 ybp; New & Old World). Used to wrap mummies. Fibers are long, smooth, straight, lusturous & yellow (from waxes) and 2 to 3 times as strong as cotton; 70% cellulose. Flax industry never became fully mechanized, since mechanically processed flax is not as good as that produced by hand, so linen is expensive. Linen is durable, but wrinkles. Ca. 2% of world’s textiles.

Flax products Linen Linseed oil –oil paints, varnishes and stains Linoleum –Latin name, linum, which means flax, and oleum, which means oil. –Manufactured by oxidizing linseed oil to form a thick mixture called linoleum cement. –Cement is cooled & mixed with pine resin, & wood flour to form sheets on a jute backing. Candle wicks: braided cordage made of flax fibers

‘tow-head’ silky strands of the flax plant were oft-times compared to hair –a 'flaxen haired maiden‘ –a 'tow-head' referring to a blond approaching whiteness Tow = short, coarse fibers of flax not used in the higher grades of spinning

Bast: Jute Jute - Corchorus sapsularis –Annual native to Asia (wet tropics) fibers are rough, brittle, and don't take dyes easily used in sacks (burlap), twine, carpet backing easily grown and processed –Bangladesh – primary world producer

Bast: Hemp Cannabis sativa - used for at least 6000 years. Fibers are stiffer than flax, used in cordage, rope, canvas, and sailcloth. Made original set of Levis from hemp. –jeans are currently made of cotton.

Bast: Ramie Boehmeria nivea - China grass –cultivated for centuries in Asia –problems with growing and processing –makes among the longest, strongest, and silkiest of all plant fibers –mechanization may result in it becoming an important fiber

Hard (Leaf) Fibers monocot leaf fibers: make better ropes than bast Sisal - Agave sisatana - Needle and thread plant –Rope, mats Henequen - Agave fourcroydes –Mayans and Aztecs made them into rough garments –Processed by squeezing leaves and scraping away fibers Abaca - Musa textilis - banana relative –used in tea bags, dollar bills, manila envelopes, cigarette filters, rope

Other fibers Coir from coconuts, a seed fiber –fibers are used as mattress stuffing, bristles in brooms and brushes, mats Kapok, surface fiber from seed pods –water-proof fibers used in life preservers, padding Pineapple cloth, from leaf fibers –used in clothing