2. The TFPIA (Textile Fiber Products
Identification Act) defines polyester
as: “a manufactured fiber in which
the fiber forming substance is any
long chain synthetic polymer
composed of at least 85% by
weight of an ester of a dihydric
alcohol and terepthalic acid.”
3. The first work on polyester
was done by the
CAROTHERS team of
chemist during the early
stages of their fundamental
research for Dupont.
When polyamides (NYLON)
appeared to show more
promise they were selected
for their development and
the polyesters were set
aside.
The early polyesters were
poor in quality and
threatened to be too
expensive.
4. Later, chemist in
Britain began
experimenting with
polyester fibers. In
1941, ‘calico
Printers’ Association
introduced a
successful polyester
fiber in 1946.
Dupont’s polyester
fiber was made
available to the
American consumers
in small quantities
and was known as
fiber V, Amilan and
then Dacron.
While the fiber
known as Dacron
was becoming
popular in the U.S.,
the same fiber called
TERYLENE, was
gaining status in
England and several
European countries.
5. Terylene
Dimethyl terepthalate and
ethylene glycol
React in the presence of N2
atmosphere and sodium as a
catalyst.
The polymerization takes place
at 196°C for three hours
Dacron
Terepthalic acid and ethylene
glycol
React in the presence of N2
atmosphere and dil. HCl as
catalyst at a definite time and
temperature
Forms a low molecular weight
polyethylene terepthate
6. The low molecular weight
Polyethylene terepthalate is
obtained
It is white, hard, flaky, solid
polymer.
PET is then heated at 280°C for
30 min. at atmospheric
pressure.
7. The polymer is then transferred to an ester changing vessel where it is kept
for 10 hours in vacuum.
Excess ethylene glycol is distilled off and the polymer is kept in the absence
of oxygen as it affects the stability of the polymer.
The low molecular weight PET is converted to high molecular weight PET
and obtained in the form of chips.
8. The chips
are mixed
and
conveyed to
an
autoclave
where they
are heated.
The molten
polymer is
filtered.
Delustering
agents,
optical
brighteners,
antistatic
agents, etc.
may be
added in
this step
The polymer
is fed to the
melt
spinning
tank.
9. The hot solution
is forced
through the
spinneret and
the fibers are
spun in air.
The fibers
solidify upon
contact with air.
11. Mixing of
chemicals
• Terepthalic acid +
ethylene glycol
Heating low mol.
Wt. polymer
• 280 C for 30 min
Ester changing
vessel
• Vacuum for 10
hours
Melting
• Chips are
meted
Spinning
12. The longitudinal view of
the fibers exhibit uniform
diameter, smooth surface,
and a straight rod like
appearance. The cross
section is usually round
but variations are
encountered in the form of
trilobal, pentalobal or oval
cross sections.
The inclusion of pigment
in the melt solution
produces fibers that are
dull or semi dull in
appearance and has a
speckled appearance
since the pigment causes
changes in light reflection.
13. • Regular &
high tenacity
fibers
available
Strength
• Better than
cellulosics
• Poor than
nylon
Elasticity
• Excellent
• Heat setting
Resiliency
• 1.38 – 1.42
Density
• Poor
Moisture
• Good when
heat set
• Shrinks
otherwise
Dimensional
stability
14. Polyester fibers melt at
temperatures from 238°- 290°C
depending upon type. As the
fiber melts, it forms a hard and
non - crushable gray or tawny
colored bead. Polyesters burn
with dark smoke and an aromatic
odor. But they do not burn as
rapidly as other fibers,. The fibers
melt and drip away form the
source of ignition
There is a minimal loss of
strength at high temperatures.
Heat setting of yarns and fabrics
is essential. Permanent pleats in
polyester fabrics once heat set in
the desired location will hold as
long as the maintainence
temperatures do not exceed the
heat set temperature
15. • Conc. H2SO4
can dissolve
the fibers
Acids
• Strong
alkalies for
prolonged
exposure
degrade
Alkalies
• Dissolve in
hot
metacresol
Organic
solvents
• No effect
Bleaches
• No effect
Sunlight /
Ageing
16. • No effect
Sunlight /
Ageing
• No effect
Biological
• Absorbs oil / oily soil
and holds it
Oleophilic
