Speciality Fibres.ppt

Mineral & Specialty Fibers

SPECIALTY FIBERS “Manmade fibers that are generally the result of considerable research and have certain characteristics which limit their use to narrow or specific areas of application.”

SPECIALTY FIBERS Polymers • • • • • • • • •

Vinyon Saran Novoloid (Kynol) Polycarbonate fibres Polybenzimidazole (PBI) fiber Alginate fibers Fluorocarbon fibers Graft copolymer fiber (Chinon II) Matrix fiber (Cordelan)

Mineral Fibers • • •

Rock wool Fiberglass Asbestos

1. VINYON 

‘VINYON’ is a generic term used for a fiber in which fiber forming substance is any long-chain synthetic polymer composed 85 % by weight of vinyl chloride units.

Three fiber variations are : 1. 2. 3.

Polyvinylchloride (100% PVC) Vinyl chloride copolymers Chemically modified Polyvinyl chloride

METHOD OF MANUFACTURE 

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Polyvinyl chloride (85%-86.5%) and polyvinyl acetate (15%-13.5%) are copolymerized. Resultant vinyl resin copolymer fiber is dissolved in acetone, filtered, deaerated and stored in heated tanks as a viscous solution. Later extruded through spinneret down a hollow tube in presence of a current of warm air to evaporate the acetone, producing filaments in tow form. Tow is passed through lubricating bath and cut into staple.

PROPERTIES      

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Relatively week High extensibility (stretch) Water repellent High resistance to acids and alkalies Does not take dyes well Non-toxic, does not mildew or support bacterial growth, not attacked by moth/ larvae/ beetles Does not support combustion

USES  

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Bonding fiber for nonwovens Widest application in heat-sealable papers, fulled and needled felts and bonded fabrics Used for molding, embossing, bulking Not suitable for spinning into yarn, however, can be blended into fabrics for industrial applications

2. SARAN 

The generic term ‘SARAN’ is used for a manufactured fiber in which the fiber forming substance is any long chain synthetic polymer composed at least 80% by weight of vinylidine chloride units.

METHOD OF MANUFACTURE 

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Vinylidene chloride is copolymerized with small quantity of vinyl chloride to produce powdered resin. Resin is melted and extruded through a spinneret into water-cooling bath. While still being cooled, it is drawn out 400% to improve crystallinity and molecular orientation, increasing strength in a manner similar to nylon.

APPEARANCE AND PROPERTIES        

Natural colour pale gold or straw Excellent abrasion resistance Stretchable Rather stiff Essentially non-absorbent Good resistance to bleaches, alkalis, acids Resistant to mildew, bacteria and insects. Non-flammable

USES 

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Monofilament yarn: car seat covers, filter fabrics, outdoor furniture tape, insert screening, grille fabrics Multifilament yarn: filter cloth, upholstery, drapery and rope

3. NOVOLOID (KYNOL) 

A generic term for manufactured fiber containing at least 55% by weight of crosslinked Novolac.

METHOD OF MANUFACTURE 

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A crosslinking agent is blended with Novolac resin at temperatures below 40 degree C, rapidly melting the blend. Melted blend is fiberized before it can cure. Resulting fibers are cured by exposing to acidic gas.

PROPERTIES    

Principal characteristic: flame resistance Natural color gold Fair abrasion resistance and resilience Excellent resistance to mildew, insects and ageing

USES 

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Flame retardant garments and protective clothing Home furnishings Blended with other fibers to enhance properties, while retaining much of the flame retardant characteristics

4. POLYCARBONATE FIBERS

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In a chemical sense, these are polyesters derived from carbonic acid.

METHOD OF MANUFACTURE 

An aromatic dihydroxyl compound is condensed with suitable carbonic acid derivative such as carbonyl chloride or esters of carbonic acid.

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Fiber is extruded through a spinneret into a monofilament.

PROPERTIES AND USES 

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Chemical composition can vary so significantly that specific properties cannot be provided Presently made only for very limited and specific purposes like basting for tailoring men’s suits

5. POLYBENZIMIDAZOLE FIBER (PBI) 

A manufactured fiber in which the fiber forming substance is a long-chain aromatic polymer having recurring imidazole groups as an integral part of the polymer chain

METHOD OF MANUFACTURE 

PBI is prepared from tetra-aminobiphenyl and diphenyl isophthalate spun via a dry spinning process using dimethyl acetamide as the solvent.

PROPERTIES     

No melting point Good strength (stretch about 30% of its length) Abrasion resistant More absorbent than other man made fibers Resistance to inorganic acid and organic solvents

USES  

Thermal protective clothing Application In aircraft, aerospace, industrial and medical uses

6. ALGINATE FIBERS

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Multifilament yarns from jellylike calcium alginate which had practical value

METHOD OF MANUFACTURE     

Fine powder of seaweed dissolved in solution of sodium carbonate and caustic soda. Coming solution bleached with sodium hypochlorite. Alginic acid then neutralized with sodium carbonate to form solution of sodium alginate. Solution extruded through spinneret into bath of acid Streams emerging coagulate into fibers which are washed, oiled, dried and wound.

PROPERTIES   

Dry strength Strength is lost when wet Nonflammable

USES 

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Used as scaffolding to support other yarns in the manufacture of lightweight, sheer and lacy fabrics Medical application for dressing Flameproof characteristics has also fiber suitable for limited applications.

FIBERGLASS 

Fiberglass is made from extremely fine fibers of glass. It is used as a reinforcing agent for many polymer products; the resulting composite material, properly known as fiber-reinforced polymer (FRP) or glassreinforced plastic (GRP), is called "fiberglass" in popular usage.

MANUFACTURING PROCESSES    

Melting Forming into Fibers Continuous Filament Process Staple Fiber Process

PROPERTIES    

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High ratio of surface area to weight Susceptible to chemical attack Traps air within Properties are the same along the fiber and across the fiber Moisture is easily adsorbed

USES      

Mats Building insulation Thermal insulation Heat/Corrosion resistant fabrics High strength fabrics Boat frames

ASBESTOS 

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General name that applies to several types of fibrous silicate minerals, existing in nature in metamorphic or altered basic and ultrabasic igneous rocks. Six minerals defined as "asbestos" are chrysotile, amosite, crocidolite, tremolite, anthophyllite and actinolite.

TYPES OF ASBESTOS

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Asbestos can be subdivided into two major classifications of minerals: Amphiboles and Serpentines. All but one form, chrysotile, are amphiboles. Chrysotile is a serpentine.

MANUFACTURING PROCESS

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Mining Separating Quality Control

PROPERTIES    

Nonflammable Insoluble in water and organic solvents Resistant to acids High Strength

USES     

Fireproofing Low density insulation board and ceiling tiles Thermal and chemical insulation Mud and texture coats Clutch plates

ROCK/STONE WOOL 

Rock wool is an amorphous silicate manufactured from rock

MANUFACTURING PROCESS 

Stone wool is a furnace product of molten stone, at a temperature of about 1600 °C, through which is blown a stream of air or steam. More high tech production techniques are based on spinning molten rock (lava) on high speed spinning wheels.