This document provides information on various functional groups that are important in polymers used to make synthetic fibers. It discusses 10 functional groups - alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, carbonyl, hydroxyl, and carboxyl. For each group, it provides a definition and description of their properties and uses, such as how they contribute to strength, toughness, crystallinity or ability to absorb moisture in fibers.

1. Assignment # 1
High Performance Fiber
“Functional group and their properties”
Name Umer Nasrullah
Reg # 15-NTU-0166
Submission Date 07-11-2016
Submission to Hritam Khan
National Textile University Faisalabad

2. Functional Group:-
Functional groups refer to specific atoms
bonded in a certain arrangement that give a
compound certain physical and chemical
properties.
Here now we describe some important
functional groups which are used in polymers
of synthetics fibers:
1. Alcohol
2. Ether
3. Aldehyde and Ketone
4. Carboxylic Acid
5. Ester
6. Amines
7. Carbonyl
8. Hydroxyl
9. Carboxyl
10. Methyl

3. Alcohols group:
Are functional groups characterized by the
presence of an -OH group. Ethers are a class of
organic compounds characterized by an oxygen
atom connected to two alkyl or aryl groups. The
structure of an alcohol is similar to that of water, as
it has a bent shape. This geometrical arrangement
reflects the effect of electron repulsion and the
increasing steric bulk of the substituents on the
central oxygen atom. Like water, alcohols are polar,
containing an unsymmetrical distribution of charge
between the oxygen and hydrogen atoms. The high
electronegativity of the oxygen compared to carbon
leads to the shortening and Strengthening of the -
OH bond.

4. Ether group:
Ethers have relatively low boiling points due to
their inability to form hydrogen bonds with each
other.
Due to the electronegativity difference between the
oxygen and carbon atoms of ether, the molecule is
slightly polar. Although they have low reactivity
overall, the two lone pairs of electrons on the
oxygen atom do afford the ether molecule some
reactivity; the ether molecule is subject to reacting
with strong acids and serves as a Lewis base.
Amide group:

5. An amide functional group consists of a carbonyl
group bonded to nitrogen. In simple amides, two
hydrogen atoms are bonded to the nitrogen (-
CONH2) while in more complex amides, the
nitrogen is bonded to one or two aliphatic or
aromatic groups (-CONR).This give the Hydrogen
bonding which causes the strength and toughness
to the textile fiber.
Amide groups are polar and are capable of
hydrogen bonding, to each other, to water and to a
variety of other substances. The capability of the
amide groups to hydrogen bond to each other leads
to crystallisation. The frequency of the amide
groups or amide density affects the crystallinity,
melting point, density, modulus, other physical
properties and dye ability. The capability of the
amide group to bond water causes nylon to absorb
moisture. So also, the amide density determines the
extent of moisture absorption. Thus the properties

6. of nylon depend upon the amide density or the
ratio of amide groups to methylene group.
Alkene group:
Alkene ... Acyclic alkenes, with only
one double bond and no other functional groups,
known as mono-enes, form a homologous series of
hydrocarbons with the general formula CnH2n.
Alkenes have two hydrogen atoms less than the
corresponding alkane (with the same number of
carbon atoms). As a consequence of п-
delocalization, aryl azo compounds have vivid
colors, especially reds, oranges, and yellows.
Therefore, they are used as dyes, and are
commonly known as azo dyes. These are use as
dyes and pigment in textile industry. An

7. unsaturated, aliphatic hydrocarbon with one or
more carbon–carbon double bond.
Ester Group:
In chemistry, esters are chemical compounds
derived from an acid (organic or inorganic) in which
at least one –OH (hydroxyl) group is replaced by an
–O–alkyl (alkoxy) group. Usually, esters are derived
from a carboxylic acid and an alcohol.
Polyester is a category of polymers that contain the
ester functional group in their main chain. As a
specific material, it most commonly refers to a type
called polyethylene terephthalate (PET).This group
are use to make polyester fibers. This material is
used very widely in clothing.

8. Aldehyde and ketone:
Aldehydes and ketones are organic compounds
which incorporate a carbonyl functional group, C=O.
The carbon atom of this group has two remaining
bonds that may be occupied by hydrogen or alkyl or
aryl substituents. If at least one of these
substituents is hydrogen, the compound is an
aldehyde. An organic compound containing a formyl
group, which is a functional group with the
structure R-CHO. A compound containing an oxygen
atom joined to a carbon atom by a double bond.
Aldehydes are also useful as solvents and perfume
ingredients and as intermediates in the production
of dyes. Many complex organic compounds are

9. synthesized using ketones as building blocks. They
are most widely used as solvents, especially in
industries manufacturing explosives, lacquers,
paints, and textiles. Ketones are also used in
tanning, as preservatives, and in hydraulic fluids.
Hydroxyl group:
Hydroxyl group bonded covalently to the carbon of
a carbonyl group (C=O) produces a carboxyl group
(C (O) OH) that is the defining group of a carboxylic
acid. When the −OH group participates in an ionic
bond, the [OH−] anion is called the hydroxide ion.
A hydroxyl or hydroxy group is a chemical functional
group containing one oxygen atom connected by a
covalent bond to one hydrogen atom (−OH).
Hydroxy groups participate in the dehydration

10. reactions that link simple biological molecules into
long chains.
Carboxyl group:
Carboxyl groups are weak acids, dissociating
partially to release hydrogen ions. The carboxyl
group (symbolized as COOH) has both a carbonyl
and a hydroxyl group attached to the same carbon
atom, resulting in new properties. Carboxylic acids
are polar. Because they are both hydrogen-bond
acceptors (the carbonyl –C=O) and hydrogen-bond
donors (the hydroxyl –OH), they also participate in
hydrogen bonding. Carboxylic acids tend to have
higher boiling points than water, not only because
of their increased surface area. Carboxylic acids are

11. used as precursors to form other compounds such
as esters, aldehydes, and ketones.
Amino group:
amino group, in chemistry, functional group that
consists of a nitrogen atom attached by single
bonds to hydrogen atoms, alkyl groups, aryl groups,
or a combination of these three. An organic
compound that contains an amino group is called an
amine. The amine functional group contains a basic
nitrogen atom with a lone pair of electrons. Amines
also display some solubility in water. However, the
solubility decreases with an increase in carbon
atoms, due to the increased hydrophobicity of the
compound as the chain length increases.