production & manufacture of fibers

8/3/2019 Production & Manufacture of Fibers

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Production & Manufacture of

Fibers



Production &Manufacture of fibers

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Fiber Forming and spinning

• Natural fibers are formed as they are

grown or produced.

• Manufactured fibers, however are made inthe laboratory.

• There are four basic processes involved:• Wet Spinning

• Dry Spinning

• Melt Spinning

• Emulsion Spinning




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Wet Spinning Process

• The polymeric material is dissolved in some solution.

• This is forced through a spinning jet – spinneret, into another liquid that

reacts with the fiber solution.• Here the fiber solution coagulated to form the fiber.

• Examples are – rayon and some acrylic fibers.




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Dry Spinning Process

• Here the fiber solution isforced through thespinneret into a warmchamber.

• The warm air causes thesolvent to evaporate, thefiber solution forms intofilaments and hardens.

• Acetate, triacetate etc.are made in this way.




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Melt Spinning Process

• In this process the fiberpolymer is melted, and themolten solution is forcedthrough the spinneret.

•

As the soft filaments emergeinto a cooler environment, theyharden into usable filamentsready for converting into yarns.

• Nylon and polyester are madein this way.




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Bicomponent and bigeneric fibers

• Bicomponent fibers are composed of two variants or modifications of thesame generic fiber type.

• Bigeneric are composed of two generic fiber types.

• As you can see above, there are three basic methods of making these.

• These are made to provide textile materials with different shrinkage levels,bulk or texture.




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Natural protein fibers

• These are obtained from animal sources.

• Hair coverings and animal secretions

• Hair fibers – wool – from the fleece of sheep, camel,

llama, vicuna etc.• Secretion fibers – silk-obtained from larva to spin

cocoon.

• Excellent absorbency, warmer, build up of static charge,

poor resistance to alkalis,• Resistance to acid (except silk, it gets destroyed).

• Good resiliency and elastic recovery.




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Natural cellulosic fibers

• These are obtained from plant sources.

• Examples are cotton, flax, jute, ramie and hemp.

• Cotton grows in warm climate with sufficient irrigation facilities.

• It comes from the seed pod of the cotton plant. It is picked by

machine.• After picking it is taken to the gin, where the fiber – cotton lint, is

separated from the seed.

• Then it is classified according to staple length, fiber grade and fibercharacter. Bales of cotton are made and shipped.

• The length of cotton fiber varies from 0.5 inches to 2.5-3 inches.

• It has excellent ability to absorb moisture, the fiber is relativelystable, but

• elastic recovery is low.




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Flax

• Flax is a bast fiber and is obtained from stalks or stems of the plant – Linum usitatissimmum

• The plant requires a temperate climate and generally cloudy skiesand adequate moisture.

• For processing the fiber, the plant is pulled by mechanical pullers, so

the root structure also comes out as a part of the stem.• After drying the flax is rippled, i.e. pulled through special threshing

machines to remove seed pods.

• Retting- the process of removing the outer woody covering to obtainthe fibers from stem, can be done in any one of the ways-

– Dew retting – Pool retting

– Tank retting

– Chemical retting

production & manufacture of fibers

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