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• Polyester is a term often defined as “long-chain polymers chemically
composed of at least 85% by weight of an ester and a dihydric alcohol and
a terephthalic acid”. In other words, it means the linking of several esters
within the fibers. Reaction of alcohol with carboxylic acid results in the
formation of esters.
• Polyester also refers to the various polymers in which the backbones are
formed by the “esterification condensation of polyfunctional alcohols and
• Less Reactive
• molecular weight liquids used as
plasticizers and as reactants in forming
urethane polymers, and linear, high
molecular weight thermoplastics such as
• Usual reactants for the saturated
polyesters are a glycol and an acid or
• More Reactive
• consists of alkyl thermosetting
resins characterized by vinyl
• Mostly Used in reinforced plastics
• Economical family of resins
Polyesters are an artificial man-made fibre , generally manufactured from petroleum from which
the constituent acids and alcohols are derived.There are three steps in the synthesizing of
• Condensation Polymerization: When acid and alcohol are reacted in a vacuum at high
temperatures it results in condensation polymerization. Once the polymerization has occurred
the material is extruded onto a casting trough in the form of a ribbon. Once cool, the ribbon
hardens and is cut into chips.
• Melt-spun Fibre: The chips are dried completely. Hopper reservoirs are then used to melt the
chips. A unique feature of polyester is that it is melt-spun fibre. The chips are heated,
extruded through spinnerets and cools upon hitting the air. It is then loosely wound around
• Drawing: The fibres consequently formed are hot stretched to about five times their original
length. This helps to reduce the fibre width. This fibre is now ready and would into cones as
filaments. It can also be crimped and cut into staple lengths as per requirements.
The name "polyester" refers to the linkage of The name
"polyester" refers to the linkage of several monomers. several
► There are many possible variation of polyester
► Polyester is a smooth fiber with an even diameter.
► The fiber diameter usually ranges from 12-25 micrometers.
► The fibers are approximately 35% crystalline and 65%
Fineness - Polyesters are avaiable in
many lengths and deniers. Very fine
denier or microdenier,some approach
0.5 denier.Microdenier fibers probably
will become increasingly important in
the apparel sector.
Color and Luster
The fiber is partially transparent and
white or off white
Physical Properties of Polyester
►Polyester filaments and staple fiber are strong because of their extremely
crystalline polymer system.
►This allow the very effective van der Waal’s forces.
►This also allows the very weak Hydrogen bonding
Elastic - Plastic Nature
• ► The stiffness and hard handle of polyester The stiffness and hard handle of polyester
• filaments are due to their extremely crystalline filaments are due to their extremely crystalline
• polymer system. polymer system.
• ► It prevents the polyester polymer from yielding It prevents the polyester polymer from yielding
• readily when the filaments of staple fiber is bent readily when the filaments of staple fiber is bent
• or flexed. or flexed.
• ► Yielding is actually a lack of stiffness and giving Yielding is actually a lack of stiffness and giving
• way the pressure. way the pressure.
• ► Polyester filaments are about as plastic as they are Polyester filaments are about as plastic as they are
• elastic. elastic.
►Polyester filaments are also hydrophobic. Polyester filaments are also
►The hydrophobic nature of the polyester The hydrophobic nature of the
polymer system attracts fats, greases, oils polymer system attracts fats, greases,
and any other greasy soils. and any other greasy soils.
►In other words we can also say that In other words we can also say that
polyester polymer system is oleophilic. polyester polymer system is oleophilic.
Chemical Properties of Polyester Fibre
• Effects of Acid
►The ester groups of the polyester polymers are resistant to acids
►This resistance is further enhanced by the extreme crystallinity of
the polymer system
Effect of Alkalis
►Alkaline conditions are economy during laundering.
►It may hydrolyses the polyester polymer at their ester groups.
►The surface polymers of polyester filaments are hydrolysed.
Brief Information on Chemical Properties
• Acids : Good resistance to acids in cold condition. But polyester degrades by
sulphuric acid at high temperature.
• Basic : Good resistance to basic in cold condition but strong NaOH dissolves
polyester in boiling.
• Effect of bleaching : Polyester does not get affected by bleaching process.
• Organic solvent : Organic solvent does not affect polyester.
• Protection Ability against mildew : Good
• Protection ability against insects : Good
• Dyes : Polyester could be dye with disperse , azoic color and some pigments
• Solvents : Following are the solvents of polyester
-Phenol (in hot condition)
►Resistant to stretching and shrinking.
• PET bottles
• Insulating Materials
• Power Belting
• Floppy Disk Liners
• Thermoformed Trays
• Glass and various Fibers
• Synthetic biodegradable polyesters are made in modified PET
polymerization facilities from petrochemical feedstock. Unlike
other petrochemical-based polymers that take centuries to
degrade after disposal, these polyesters break down rapidly to
CO2 and water in appropriate conditions where they are exposed
to the combined attack of water and microbes. These products
meet U.S., European, and Japanese composting standards,
typically breaking down in 12 weeks under aerobic conditions.
• Synthetic biodegradable polyesters fall into two broad
categories. One is highly amorphous, imparting flexibility and
clarity comparable to a conventional LDPE copolymer. A second
group of semi crystalline polyesters is more rigid, with properties
similar to PET, PP, or PS.
• Man made fibers – Moncrieff R.W
• Textile Science – Hudson P.B ETC