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Unformatted text preview: CHAPTER 12-HIGH PERFORMANCE & SPECIALTY FIBERS- Types of fibers with somewhat ltd. Use or represent relatively recent developments in tech. of manufacture fier production- Include: high performance fibers engineered for or used in industrial and specialty products; & mineral and metallic fibers which have been used for many years for particular functional or aesthetic purposes HIGH-STRENGH, HIGH-MODULUS FIBERS- Very strong fibers & usually very stiff & resistant to bending/stretching- Ex: para-aramids & gel-spun polyethylene CARBON FIBERS- Major apps in industrial uses- Within industry, carbon fibers graphite fibers sometimes used interchangeably graphite fibers actually special type of carbon fiber with crystal ( graphitic ) structure unique to true graphite fibers- Manufacture o Made by first spinning a precursor fiber thats later converted to 100% C Pitch: precursor frequently used; material derived from coal tar OR petroleum tar Melt spun into fibers with range of crystallinitiesmore crystalline & oriented, the stronger final C fibers will be Less expensive raw material from which substantial quantities of industrial & general grade materials manufacture from Rayon used @ one time Lyocell (very crystalline) now produced PAN : polyacrylonitrile; most common starting material to convert to C fibersheated to temps >1800F (1000C)driving off most of H, N, & other atoms to leave only C on further heating to 4500F (2500C), crystalline graphite structureproduces extremely high modulus graphite fiberdevelops *similar high-heat treatment given to melt spun pitch fibers to eliminate H atoms- Properties o Black in color o Fairly smooth appearance o Very high modulus & tenacity ( 13-28 g/d)due to crystalline structure o Heavier than other manufactured fibers BUT lighter wt. than glass or steel (competitors for end use)- Uses o Often as reinforcing material in plastic compositeshigh strength increase toughness of composite material & black color not detriment because fibers embedded in matrix Light wt structures for air & spacecraftnew 787 Dreamline from Boeing Brake discs for jet airplanes o Sporting goods Golf club handles Tennis racquets Fishing poles Skis Canoes kayaks o Construction industry Bridges & buildings o Automotive industry o Medicine Graphite materials used for implantation to replace bone o **add to cost of many items because expensive (~5x cost of PET polyester)cost is LESS than aramids & some other high-tenacity, high modulus fibers GLASS FIBERS- Owens-Corning Glass Co. initiated m ass production- Made from glass that has be en m elted and extruded into long, fine filaments- Made from silica sand and limestone ; plus small amt. of other constituents such as soda ash, borax, & aluminum hydroxide o Quantities of these varied depending on qualities desired in glass fiber- Manufacture o Produced in both continuous filament form and staple lengths...
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This note was uploaded on 05/06/2010 for the course HUEC 2040 taught by Professor Staff during the Fall '08 term at LSU.

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