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HUEC 2040 EXAM 2 NOTES Monday, September 21, 2009 Manufactured Fibers (pages 23-36) CH. 2 Two Major Classifications 1. Regenerated Fibers a. From naturally –occurring polymer materials i. Unmodified – rayon ii. Modified – acetate, triacetate 2. Synthetic Fibers a. Synthesized from chemicals – nylon Fiber Formation (Basic Steps) 1. Polymer prepared/converted into liquid a. Spinning dope i. Solution dope/mix ii. Polymer melt b. Additives to molten polymer before extrusion 2. Liquid polymer extruded through spinneret a. This is where the fibers are forced through the holes and solidifying into long thin fibers 3. Drawing a. All manufactured fibers are drawn in to some certain extent b. Makes the fibers stronger c. You are pulling the polymer chains into a more orientated strain d. Elongating the fiber e. Drawn more are less absorbency, drawn less is more absorbent Polymer Pre-pared Process 1. Manufactured Natural Polymer a. Cellulose b. Regenerates into a new physical form i. Wood pulp, cotton linters ii. Processed into pure cellulose pulp 2. Manufactured Synthetic Polymer a. Chemicals used to from a polymer not a previously existing in a natural state Spinning Process 1. Liquid polymeric melt/solution forced though spinneret a. Small number of hole – spinneret i. Produce filaments, not cut into short fibers b. Larger number of holes – spinneret i. Produce filaments, cut into staple length
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Manufactured Fiber Forms 2. Multifilament a. Multiple filaments combined unto a yarn 3. Monofilament a. Single filament used as a yarn Step 2 – Spinning Wet Spinning Polymeric material dissolved in a solvent, forced through spinneret into a liquid bath o Viscose rayon, some acrylics Variation o Dry-jet wet spinning o Spinneret slightly above bath drawn before solidified o Lyocell Dry Spinning Polymeric material dissolved in a solvent, forced through a spinneret into warm air that evaporated the solvent o Acetate, meta-aramids, most spandex, some acrylics Irregular cross section o Solvent evaporates from the exterior, then interior As the interior disappears, that’s when the skin collapses o Skin collapses Melt Spinning Polymeric material heated to melting and forced through spinneret into cool air Nylon, polyester, olefin, glass This method takes advantage of the thermoplastic properties of these synthetic fibers Most efficient and most versatile method o Simplest and cheapest No solvent expense or recovery Only works for some of the fibers
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