CTE 1401 Study Guide Exam 2 Spring 2013Chapter 6 Regenerated cellulosicWhy are manufactured cellulosic fibers called “regenerated”?- They are cellulose (or protein), produced from natural substances containing cellulose (or protein) in an unusable form. Treated with chemicals to produce a solution that can be regenerated or reformed as a fiber Why are the properties of the manufactured fibers similar to the Natural cellulosic fibers?-Rayon is composed of cellulose, like cotton.How have the properties of rayon improved with new research and development?- A Japanese researcher modified the viscose process to develop a fiber with a physical structure more like that of cotton. High wet modulus came about which means like cotton they have greater resistance to deformation when wetWhat are some of the end uses of rayon?- Most common type of rayon. Apparel, interior fabrics – Often blended with other fibers to improve performanceNon-woven applications– “cotton” balls, disposable dust cloths, disposable diapersHigh Wet Modulus (HWM) rayon (newer version)– Has greater strength; stretches less– Used for cords in tires and some apparel.What was the first thermoplastic fiber?-AcetateWhat is the difference between the properties of acetate and rayon?-Acetate is dry spun, it dissolves in acetone, and properties are desirable aesthetics but low strength and abrasion resistance. Rayon properties are good drape and aesthetics, low strength and low wrinkle resistanceWhat are some of the end uses of acetate?- Household and apparel textiles-Looks nice, feels nice, is inexpensive, Special occasions—costumes, graduation robes, Suit linings, Cigarette filtersWhy was lyocell approved as a new generic fiber even though it has similar properties to rayon?- The FTC states, “ Where the fiber is composed of cellulose precipitated from and organic solution in which no substitution of the hydroxyl groups takes place and no chemical intermediates are formed.7-11: Manufactured FibersWhat is the best website for finding information about manufactured fibers?What is a “manufactured” fiber?-Produced commercially through regeneration from natural materials or synthesized from chemicals What was the first synthetic fiber?- NylonHow does the production of manufactured synthetic fibers differ from regenerated fibers?- Regenerated fibers are made form natural (polymer) materials that cannot be used for textiles in their original form but that can be regenerated into usable fibers by chemical treatment and processing. Synthetic fibers are made from materials that are created synthetically in a chemical processWhat are the steps to produce a manufactured fiber?• Develop the solution (dope)• Extrude through a spinneret• Coagulate or solidify the fiber• Draw the fiberHow do the three ways of creating manufactured fibers differ from each other: dry spinning, wet spinning, and melt spinning? Which one uses the fewest chemicals?- Dry spinning is when natural materials dissolved in chemical, extruded into warm air. Melt spinning is when chemicals combined to create substance usually as a flake or bead. Wet spinning is when natural materials dissolved in chemicals, extruded in to chemical bath. The one that uses the fewest chemicals is melt spinningWhat is “drawing” fiber? What does it accomplish?- Drawing is when the filaments are stretched to modify the molecular arrangements within the fiber. Drawing makes the filament both narrow and longer. * From slide: Godet wheels draw out fiber to increase polymer orientation… more drawing= more crystallinityKnow the unique properties and end uses for:Nylon• -Physical– Appearance• Normally round, but may be shaped– Example: trilobal structure helps to hide soil• Light weight– Allows final product to be lightweight but strong• Mechanical– Very strong (good for soft-sided luggage, seat belts, hosiery– Stretches easily, good recovery– Good resilience; wrinkle resistant, carpets don’t show foot marks– Good abrasion resistance• Chemical– Moderately absorbent; dries quickly – Poor electrical conductivity (lots of static cling)– Dyes easily (picks up colors in laundry)– Melts easily• Environmental– Better resistance to UV rays than natural fibersEnd Uses• Nylon more expensive than many other synthetics• Carpets• Stretch fabrics– Swimwear, hosiery• Sports wear• Ropes• Air bags• Parachutes• Fishing linesAramid• -Molecular structure makes them very stiff• High strength• Resistant to high temperatures (up to 700 )⁰– Do not melt; just decomposeEnd Uses• Expensive; used in high-end products where light weight, strength, and heat resistance are a priority• Race driver’s and fire fighter’s clothing– Other protective clothing (astronauts, safety gloves, bullet proof vests)• Reinforcement fibers– Tires, aircraft, canoes, tennis racquets, fishing rodsPolyester• -Appearance– Can be spun with a variety of cross sections, which affect appearance and performance– Can be made into microfibers• Strength– Very strong; strength not affected by moisture• Low stretch• Excellent resilience– Often blended with cotton to increase wrinkle-resistanceEnd Uses• Most widely-used fiber in the world• Apparel• Home furnishings• Pillow and toy stuffing• Outdoor textiles (furniture, awnings– Resistant to moisture and microorganisms• Industrial textiles– Firehoses, beltingAcrylics• -Light weight• Properties are similar to wool– Relatively weak– Good elongation and recovery– Modacrylics are flame resistant; self-extinguish– But . . .• Low resiliency; usually knitted instead of woven to reduce wrinkling• Low absorbency and conductivity– Gets staticEnd Uses• Used as a substitute for wool– Sweaters, blankets, socks– Artificial fur– Stuffed toys– Knitting yarns– WigsOlefin• -Very lightweight– Inexpensive• Very non-absorbent; must be dyed in solution• Weaker than nylon or polyester• Low melting point• Good wicking propertiesEnd Uses • Carpets and Rugs– Carpet backing• 32% of carpet and rug market• Home furnishings– Very stain resistant• Active Sportwear– Good wicking abilities• Geotextiles– Degrades in sunlight (so doesn’t have to be removed after plant growth is established• Disposables– Shopping bags– Diaper liners– Cleaning clothsSpandex• -Can stretch up to 5 times its length and recover•