LECTURE BY IMRAN RAZA

1. Spinning of Man made Fibers (Production of Filament)
 In 1862 Ozanam invented the spinning jet or spinneret which was a small thimble like
nozzle with one or many holes, through which the fiber solution (dope) could be pumped
out.
 Platinum or gold was the metal used due to the fact that these are inert. Today, however,
stainless steel is commonly used.
 Laser beams are used to make holes which can be round or of any desired shape.
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 Physical features of these fibers (length,
diameter & cross-sectional shaped) can be
controlled.
 For production of filaments, about 350
holes are punched on 1 spinning jet.
 The process of spinning could be broken
down into 3 components i.e
pre-spinning steps, actual spinning &
post-spinning steps.

2. Pre-Spinning Steps:
These includes additions of delustrants (for reducing the bright luster of manufactured
fibers) with manufactured fiber.
Whiteness or optical brighteners and sometimes even dye pigments (solution dyeing).
Additions of dye pigment is called dope dyeing and is commonly used for fibers that have a
very low moisture regain i.e Olefins.
Actual spinning
There are 3 common steps for chemical spinning:
o Conversion of a polymer into a liquid or spinning solution, also called a dope.
o Extruding the solution through a spinneret i.e pumping the dope.
o Solidification of the extruded material into filaments (solid)
Post-Spinning Steps
These are common to all methods of chemical spinning and include drawing (i.e stretching)
to improve orientation & heat setting.
Spin finishes are also applied to counter act the problems of static charge build up.
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3. Spinning of Man-Made Fibers (Chemical Spinning)
There are three main method of spinning fibers.
Melt Spinning :
Chip of solid polymer are dropped from a hopper into a melter where heat converts the solid
polymer into a viscous liquid. Melt spinning is simpler and cheaper then other spinning
methods , therefore it is used except when polymer can not be melt spun , when the molten
polymer emerge from the spinneret hole a cool air is passed over the fibers causing it to
hardness. Nylon and Polyster are the most common melt spun fibers.
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4. Dry Spinning
Polymer that cannot be melt spun undergo other methods of spinning, such as dry spinning.
Dry spinning requires the dissolving of the polymer in a solvent to convert it into liquid. The
solvent substances are also used because they are safe and can be reclaimed and reused.
The polymer and the solvent are extruded through a spinneret into a circulating hot gas that
evaporate the solvent from the polymer and causes the filament to harden. The Solvent is
removed and recycled to be used again. Acetate fibers and some Acrylic fibers are dry spun.
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5. Wet Spinning
Wet spun polymers are like dry spun polymer converted into liquid form by dissolving them
in a suitable solvent. The polymer solution is extruded through a spinneret into a liquid bath.
The bath causes Coagulation and precipitation of the fiber. Solvents are usually recovered
from the liquid bath and are recycle. Viscose Rayon and some acrylics are wet spun.
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6. Imran Raza Malik

7. Comparison Of Natural And Man Made Fibers
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Natural
 Produced Seasonally
 Vary in quality because they are
affected by weather & insects.
 Lack Uniformity
 Cohesive
 Physical structure depends upon natural
growth of plant or animal.
 Chemical composition and molecular
structure depend on the natural growth.
 Natural Fibers are staple fibers except
silk.
 Properties are inherent and can be
changed by yarn and fabric finish.
Man Made
 Continuous Production
 Uniform in Quality
 Uniform
 Not Cohesive
 Physical structure depends upon fiber
spinning & spinneret.
 Chemical composition and molecular
structure depend on starting material.
 All synthetic fibers are filaments.
 Properties are inherent but can be
changed by varying spinning solution
and spinning conditions