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Midterm

CTD 215 Midterm: Textiles Exam 2 Notes

5 Pages
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Department
Clothing, Textiles and Interior Design
Course Code
CTD 215
Professor
Dr.Thompson

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Description
Textiles Exam 2 Notes • What is regain and tenacity? What does it tell us about a fiber being considered? ➢ Regain: measure of the moisture content of a fiber in equilibrium with a standard testing atmosphere. ➢ Tenacity: describes the strength of a fiber; it is usually referred to as breaking tenacity, which describes the force at which the fiber ruptures or breaks. ➢ If the fiber has high regain and high tenacity then the molecules are strong • Fibers, origins, properties, and end uses. ➢ Rayon: regenerated cellulose; starting material is purified, bleached wood pulp. o Chemicals are added to the cellulose to convert it into a derivative which can be dissolved to form a viscous polymer solution (viscose) o The viscose is extruded through gold or platinum spinnerets immersed in an acid bath (wet spinning). The cellulose derivative is decomposed by the acid in the bath and cellulose is regenerated, as continuous filaments. o These filaments are stretched, washed and dried, then either packaged as continuous filament material or chopped into short staple fibers. o First manufactured fiber of regenerated cellulose o Low dp, low crystallinity  low tenacity, lower wet tenacity; low resilience  wrinkles; weakens when wet; high regain, high dyeability, lower ironing temperature, low abrasion resistance  shrinks ➢ Lyocell: purified, bleached wood pulp that is then dissolved in a special solvent. o Processed by wet spinning and then the fiber is used in either filament or staple form. o It’s pure cellulose and it’s properties are superior to rayon. o Tenacity is close ot cotton and loss of tenacity in water is only about 30%. Wash shrinkage is extremely low. o Fibers undergo “controlled fibrillation” in some treatments o Round cross section and smoother longitudinal structure o Strong; weaker when wet; adequate breaking elongation; poor resistance to abrasion; good regain; no static; soft hand ➢ Acetate: modified cellulosic fibers that begins as purified bleached wood pulp. o Processed through dry spinning o Has few OH groups o Loses 50% if its strength when wet. Not a good fiber to launder o Poor elastic recovery o Degraded by sunlight ➢ Triacetate: modified cellulosic fiber that starts as purified bleached wood pulp o Dry spun o Has no OH o May be used as a generic description of the fiber o Good resilience and can be heat-set o Has good dimensional stability ➢ Acetate and Triacetate: the hydroxyl (OH) groups in cellulose are replaced by acetyl groups o The difference between the two is in the extent to which this replacement takes place o Irregular cross section; longitudinal striations; can be varied by spinneret, fiber is clear if bright  opaque if dull; very weak  high amorphous ➢ Alginate: regenerated protein fibers o Soysilk: from soybean waste; durable; good drape; good comfort; apparel o Silk Latte: from milk proteins; soft hand; dyeable; apparel ➢ Bamboo: soft; silky hand; similar to high quality ramie ➢ Nylon: the first wholly “synthetic” fiber to be produced o Starting materials are polymers manufactured from chemicals derived from petroleum; the polymers are not found in nature o Numbers after nylon indicate the number of carbon atoms o Melt spinning o Filaments are stretched and packaged o Round cross-section o Used in women’s hosiery, lingerie, and carpet markets o Lustrous; low specific gravity  light fabric o High elongation; low modulus; excellent elastic recovery and resilience; low moisture absorption  staticy; high abrasion resistance  tough; oleophilic  attracts oily stains; susceptible to UV lights ➢ Polyester: often blended with other fibers, particularly cotton, rayon, and wool o High elastic recovery and resilience  wrinkle resistant o Low moisture regain; wicking ability but difficult to dye; withstand sunlight, UV, and weathering o Used in apparel, industrial, seat belts, and insulation ➢ Olefin: starting materials are polymers manufactured from chemicals derived from petroleum; polymers are not found in nature o Produced by the addition of propylene or ethylene o Used in either filament or staple form o Lightest in weight; zero moisture regain; great wicking ability o Melt spun  any shape, smooth; undyed yarns are clear o High tenacity; good abrasion resistance; high elastic recovery; good modulus; high crystallinity due to no polar groups o Extremely difficult to dye; static charges build up o Used in activewear, indoor/outdoor carpeting, towropes, body armor, and sails ➢ Acrylic and Modacrylic: copolymers, made from two monomers which each could produce their own polymer o Starting materials are polymers manufactured from chemicals derived from petroleum o Principle component is AN (acrylic AN content>modacrylic AN content) ▪ Amount of AN and copolymer determines the end properties o Wet or dry spun and then stretched and packaged o Acrylic used to form yarn o Cross-section is varied; surface is varied; usually delustered; light weight o Tenacity: weak to medium; modulus: moderate to low; high elastic recovery; good resilience; low moisture regain o Piling: fibers crack with abrasion o Modacrylic: flame resistant, excessive shrinkage, used in wigs and fake fur fabrics ➢ Spandex: elastometric fiber with high elongation and low modulus (low resistance to extension) o Also called Elastane o Lycra by DuPont o Derived from petroleum and then either dry or wet spun then used in a continuous filament form o Various cross-sections
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