I am a student of Textile engineering. Studies at Dhaka university of Engineering and Technology, Gazipur (DUET)

1. Assignment
TE-2603
Fibrous Materials and Textile Physics-2
Topics: Aramid Fiber
Submitted by:
Name:
ID:
Semester & Year:
Department:
Md. Rasel mondal
175013
2/2
Textile Engineering
Submitted to:
Mr. Abu Yousuf Mohammad Anwarul Azim
Assistant Professor, Department of TE
Dhaka University of Engineering & Technology, Gazipur

2. Introduction:
All fibers used in polymer engineering composites can be divided into two categories,
namely synthetic fibers and natural fibers. Synthetic fibers are the most common. Although there
are many types of synthetic fibers, glass, carbon and aramid fibers represent the most important.
Kevlar is an aromatic polyamide or aramid fiber introduced in early 1970s by DuPont. Aramid
fiber was the first organic fiber used as reinforcement in advanced composites with high enough
tensile modulus and strength. They have much better mechanical properties than steel and glass
fibers on an equal weight basis. Aramid fibers are inherently heat- and flame-resistant, which
maintain these properties at high temperatures.
Figure-1: Aramid fiber
Definition:
The term “aramid” is designated for the fibers of the aromatic polyamide type in which at least
85% of the amide bonds (CONH) are attached directly to two aromatic rings, as defined by the US
Federal Trade Commission. The configuration of these bonds as either para or meta is often used
to classify the polymer.

3. Figure-2: Structure of aramid fiber
Also Known As: Kevlar (Trademark of DuPont), Twaron (Trademark of Teijin)
History of Aramid Fiber:
Aromatic polyamides were first introduced in commercial applications in the early 1960s, with a
meta-aramid fiber produced by DuPont under the tradename Nomex. Aramid fiber, which handles
similarly to normal textile apparel fibers, is characterized by its excellent resistance to heat, as it
neither melts nor ignites in normal levels of oxygen. Aramid is used extensively in the production
of protective apparel, air filtration, thermal and electrical insulation as well as a substitute for
asbestos. Meta-aramid is also produced in the Netherlands and Japan by Teijin under the tradename
Teijinconex, in China by Yantai under the tradename New Star and a variant of meta-aramid in
France by Kernel under the tradename Kernel.
Types of aramid fibers:
There are two main types of aramid fibers.
1. Meta- aramid
2. Para- aramid
Production of Aramid fiber:
➢ Meta-aramid:
Meta-aramid is synthesized by a poly-condensation reaction between m-phenylene diamine and
isophthaloyl dichloride in an n-methyl pyrrolidone solvent (Jassal & Ghosh, 2002). The reaction
is shown in Figure no 3.
Figure-3: Production of meta-aramid polymer

4. ➢ Para-aramid:
Para-aramids are also synthesized by a poly-condensation reaction between p-phenylene diamine
with terephthaloyl dichloride in an n-methyl pyrrolidone solvent. The reaction is shown in Figure
4.
Figure-4: Production of para-aramid polymer.
Meta-aramid fibres are produced from a solution spinning process, which is also known as wet
spinning (see Figure 5). The meta-aramid polymer is dissolved in 100% sulphuric acid to form
aramid dope. This polymeric dope is forced through the spinneret immersed in a spin bath
containing water to obtain fibres. Sulphuric acid solvent in the dope is removed in the water bath
and the fibres formed are drawn, dried and heat-set. Para-aramid fibres are made by the dry-jet,
wet-spinning method (see Figure 6). The para-aramid polymer is immersed in 100% sulphuric acid
(solvent) to form a liquid crystalline state and kept only partially liquid, which keeps the polymer
chains together. The polymeric dope is forced through the spinneret at 100 °C. The fibre becomes
highly oriented in the air gap before entering the spin bath containing water. Sulphuric acid solvent
in the dope is removed in the water bath and the fibres formed are heat-set to obtain highly oriented
fibres.
Figure-5: Production of meta-aramid filament yarn by solution spinning

5. Figure-6: Production of aramid filament yarn by dry jet wet spinning
Figure-7: Aramid fiber production process

6. Aramid fiber Properties:
▪ Fiber Properties:
Aramid fibers have medium to ultra-high strength, medium to low elongation and
moderately high to ultra-high modulus with the densities ranging from 1.38g/cm3. Heat-
resistant and flame-retardant fibers contain high proportion or meta-oriented phenylene
rings, whereas ultra-high strength high-modulus fibers contain mainly para-oriented
phenylene rings.
▪ Fiber Structure:
In aramid fibers a series of synthetic polymers in which repeating units have large phenyl
rings are linked together by amide groups. Amide groups (CO-NH) form strong bonds
that are resistant to solvents and heat. Phenyl rings are bulky six-sided groups of carbon
and hydrogen atoms that prevent polymer chains from rotating and twisting around their
chemical bonds.
▪ Mechanical Properties:
Aramid yarn have breaking tenacity of 3045 MPa, in other words more than 5 times than
this steel (under water, aramid is 4 times stronger) and twice than this of glass fiber or
nylon. High strength is result of its aromatic and amide group and high crystallinity.
Aramid retains strength and modulus at temperatures as high as 300 degrees Celsius. It
behaves elastically under tension. When it comes to severe bending, it shows non-linear
plastic deformation. With tension fatigue, no failure is observed even at impressively
high loads and cycle times. Creep strain for aramid is only 0.3%.
▪ Chemical Properties:
All aramids contain amide links that are hydrophilic. However, not all aramid products
absorb the same moisture. The PPD-T (poly-phenylene terephathalamide) fiber has very
good resistance to many organic solvents and salt, but strong acids can cause substantial
loss of strength. Aramid fibers are difficult to dye due to their high T,g. Also, the
aromatic nature of para-aramid is responsible for oxidative reactions when exposed to
UV light, that leads to a change in color and loss of some strength.
Thermal Properties:
Aramid fibers do not melt inn the conventional sense but decompose simultaneously.
They burn only with difficulty because of limited oxygen Index values. It should be
mentioned that at 300 degrees Celsius some aramid types can still retain about 50% of
their strength. Aramid fibers show high crystallinity which results in negligible shrinkage
at high temperature.
To sum up, aramid general characteristics are:
▪ High strength

7. ▪ Resistance to absorption
▪ Resistance to organic solvent
▪ Good chemical resistance
▪ No conductivity
▪ No melting point low flammability
▪ Excellent heat, and cut resistance
▪ Sensitive to acids and ultraviolet radiation
Advantages of aramid fibers:
Aramid main advantages are high strength and low weight. Like graphite, it has slightly
negative axial coefficient of thermal expansion, which means aramid laminates can be made
thermally table in dimensions. Unlike graphite, it is very resistant to impact and abrasion
damage. It can be made waterproof when combined with other materials like epoxy. It can be
used as a composite with rubber retaining its flexibility. High tensile modulus and low breakage
elongation combined with very good resistance to chemicals make it the right choice for different
composite structural parts in various applications.
Disadvantages of aramid fibers:
On the other hand, aramid fiber has a few disadvantages. The fibers absorb moisture, so aramid
composites are more sensitive to the environment than glass or graphite composites. For this
reason, it must be combined with moisture resistance materials like epoxy systems. Compressive
properties are relatively poor too. Consequently, aramid fiber is not used in bridge building or
whenever this king of resistance in needed. Also, aramid fibers are difficult to cut and to grind
without special equipment’s (e.g. special scissors for cutting, special drill bits). Finally, aramid
suffer some corrosion and are degraded by UV light. For this reason, they must be properly
coated
Aramid Fiber Characteristics
▪ Good resistance to abrasion
▪ Good resistance to organic solvents
▪ Nonconductive
▪ No melting point, degradation starts from 500°C
▪ Low flammability
▪ Good fabric integrity at elevated
▪ Sensitive to acids and salts
▪ Sensitive to ultraviolet radiation
▪ Prone to static build-up unless finished

8. Uses of Aramid Fiber
▪ Flame-resistant clothing
▪ Heat protective clothing and helmets
▪ Body armor [competing with PE based fiber products such as Dyneme and Spectra
▪ Composite materials
▪ Asbestos replacement (e.g. braking pads)
▪ Hot air filtration fabrics
▪ Tires, newly as Sulfone (sulfur modified Twaron)
▪ Mechanical rubber goods reinforcement
▪ Ropes and cables
▪ Wicks for fire dancing
▪ Optical fiber cable systems
▪ Sail cloth (not necessarily racing boat sails)
▪ Sporting goods
▪ Drumheads
▪ Wind instrument reeds, such as the Fibracell brand
▪ Speaker woofers
▪ Boat hull material
▪ Fiber reinforced concrete
▪ Reinforced thermoplastic pipes
▪ Tennis strings (e.g. by Ash away and Prince tennis companies)
▪ Hockey sticks (normally in composition with such materials as wood and carbon).
Comparison among Aramid fiber, Carbon fiber and Glass
fiber:

9. A. Tensile strength:
Material Fiber strength
Glass 3450
Carbon 4127
Kevlar 2757
The strength depends upon the manufacturing process, precursor material and after
treatment. From above figure, the tensile strength of Kevlar is less than both of carbon
and glass fiber. Wherever highly tensile strength is required, there Kevlar is not possible
for optimizing
B. Density and strength to weight ratio:
Material Fiber strength Laminated strength Density of
laminate grams/cc
Strength to
weight ratio
Glass 3450 1500 2.66 564
Carbon 4127 1600 1.58 1013
Kevlar 2757 1430 1.44 993
The above table represents the lighter weight of Kevlar (Aramid), and next is carbon fiber
and the glass fiber are heavier. Kevlar has strength to weight ratio as compare to E glass.
Therefore, we can save the materials for same purpose.
C. Modulus of elasticity:
Material Young’s modulus
Glass 30-40
Carbon 125-181
Kevlar 70.5-112.4
The Young’s modulus of carbon fiber is higher than both of glass and Aramid fiber. The
stiffness of carbon fiber is twice of aramid and 5 times of Glass fiber. when carbon fiber
tends to fail then it does not show clearly deformation.
D. Ultra-violate Degradation:
When sun light come to in contact of Aramid fiber, then it occurs degradation, but sun light
does not affect the carbon fiber and glass fiber.

10. Conclusion:
Aramid fiber is great composite material for het resistance. It is mostly used in protective product
for the safety purpose it has great properties but it has some disadvantage in industry, composite
material aramid fiber producing product mainly. it is useful for beneficial.