Polyester is a synthetic polymer derived from petroleum-based dicarboxylic acids and diols through a polycondensation reaction. Common polyesters include polyethylene terephthalate (PET) used in clothing, containers, and film. Polyester fibers are strong, wrinkle-resistant, and hydrophobic, making them useful for outdoor clothing and home furnishings. The production of polyester involves polymerization, spinning into fibers, and drawing to strengthen the fibers. Compared to cotton, polyester dries quickly but does not absorb water and can accumulate static electricity. Polyester is widely used in clothing for its durability and ease of care.

1. Presented by:
M Faisal Waqas, Shahid Ul Rehman, M Umer Farooq

2.  Polyesters are one of the most important and most used
polycondensation polymers and are derived from
dicarboxylic acids and diols.
 Polyester is a polymer class containing ester functional
group on polymeric main chain.
 Polyester term is usually used for polyethylene
terephthalate (PET), despite the numerous polyester
forms are present.
 Polyester is a synthetic fabric that's usually derived
from petroleum. This fabric is one of the world's most
popular textiles, and it is used in thousands of different
consumer and industrial applications.

3.  1926: American scientist Wallace Carothers first
discovered that alcohols and carboxyl acids could be
mixed to create synthetic fibers. Unfortunately, his
work on polyester was temporarily shelved to focus
on nylon.
 1939: British scientists John Winfield and James
Dickson continued Carother’s work. By 1941, they
patented polyethylene terephthalate (PET), which
would form the basis for synthetic fibers.
 1951: Polyester was first introduced to the public as a
miracle fabric that could be worn, pulled, and washed
without any wrinkling or signs of wear-and-tear.

4.  Polyester can be classified into two types
 1.Saturated polyesters.
 2.Unsaturated polyesters.
 Saturated polyesters refer to that family of polyesters
in which the polyester backbones are saturated. They
are thus not as reactive as unsaturated polyesters.
They consist of low molecular weight liquids used as
plasticizers.
 Unsaturated polyesters refer to that family of
polyesters in which the backbone consists of alkyl
thermosetting resins characterized by vinyl
unsaturation. They are mostly used in reinforced
plastics.

5.  The structure in the picture is called
poly(ethylene terephthalate), or PET for
short, because it is made up of ethylene
groups and terephthalate groups.

The ester groups in the polyester chain are polar, with the carbonyl
oxygen atom having a somewhat negative charge and the
carbonyl carbon atom having a somewhat positive charge. The
positive and negative charges of different ester groups are
attracted to each other. This allows the ester groups of nearby
chains to line up with each other in crystal form, which is why they
can form strong fibers.

6.  In condensation polymerisation, when the
monomers join together a small molecule gets
lost.
 A Polyester is made by a reaction involving an
acid with two –COOH groups, and an alcohol
with two –OH groups.
 The acid is benzene-1,4-dicarboxylic acid (old
name: terephthalic acid).
 The alcohol is ethane-1,2-diol (old name:
ethylene glycol).

7.  Now imagine lining these up alternately and
making esters with each acid group and each
alcohol group, losing a molecule of water
every time an ester linkage is made.

8.  Polyesters are generally manufactured from
petroleum from which the constituent acids and
alcohols are derived.
There are three steps in the synthesizing of
polyester,
1) Polymerization
Condensation polymerization occurs when the
acid and alcohol are reacted in a vacuum at
high temperatures. The polymerized material is
extruded in the form of a ribbon onto a casting
trough or cooling wheel. After the ribbon
hardens, it is cut into chips.

9. 2) Spinning
The chips are dried and then put into hopper
reservoirs for melting. Polyester is a "melt spun"
fiber, which means that it is heated, extruded
through the spinnerets, and cools upon hitting the
air. From there it is loosely wound around cylinders.
3) Drawing
The fibers are then hot stretched until they are about
five times their original length in order to decrease
their width. The fiber is then wound onto cones as
filaments or is crimped and then is cut into staple
lengths.

10.  Polyester fabrics and fibers are extremely strong. It is
durable ,resistant to most chemicals, stretching and
shrinking . It is also wrinkle resistant and abrasion resistant.
 Polyester is hydrophobic in nature and quick drying.
Polyester retains it's shape and hence is good for making
outdoor clothing for harsh climates. It is easily washed and
dried.
 Cotton is comfortable to wear. It has natural cellulosic fiber.
Cotton is made from the cotton ball. It absorbs water, slow in
drying, resists static electricity build up. Cotton wrinkles
easily, can withstand heat, detergents and bleach.

11.  Very high heat can "melt" the fabric .
 Easy to wash ,dry and wear .
 Does not absorb water (can be uncomfortable when worn
next to the skin in warm weather unless loosely woven)
but it can be produced in such a way (as in polypropylene
and microfibers) as to "wick" water away from the skin .
 Attracts static electricity which also attracts dirt and lint .
 Although they do NOT absorb water, they DO absorb oil
and grease.
 Resist soiling, but once an oil based stain soaks in, it can
be difficult to clean.
 Strong fiber (but nylon is stronger) .
 Often blended with cotton or even wool to add crease
resistance.

12.  Polyester is used in the manufacturing of all kinds of clothes
and home furnishings like bedspreads, sheets, pillows,
furniture, carpets and even curtains.
 Hydrophobic nature: High tenacity and good durability
makes polyester the choice of fabric for high stress outdoors
use. Polyester is also a strong fiber that is hydrophobic in
nature. It is thus ideal for clothing to be used in wet and
damp environments.The fabric is also coated with a water-
resistant finish and further intensifies the hydrophobic
nature.

13.  Creating insulation: By creating hollow fibers it
is also possible to build insulation into the
polyester fiber. Air is trapped inside the fiber,
which is then warmed by the heat of the body.
This keeps the body warm in cold weather.
Another method to build insulation is to use
crimped polyester in a fiberfill.
 Wrinkle resistant: Polyester is also wrinkle
resistant and is used very often in everyday
clothing like pants, shirts, tops, skirts and suits.
Used either by itself or as a blend, it is also stain
resistant and hence is very popular.

14.  The most common use of polyester today is to
make the plastic bottles that store our much
beloved beverages.
 An unusual and little known use of polyester is in
the of balloons. These are made of Mylar – a kind
of polyester film and aluminum foil.
 Polyester is also used to manufacture high
strength ropes (Due to its strength and tenacity )
thread, hoses, sails, floppy disk liners, power
belting and much more in industries.