Man made fibre VVI QUESTIONS.pdf.PD Textile engineeringF

Man made fibre

1. MANMADE FIBRE
TECHNOLOGY
BY ANKIT SINGH


Vvi questions

2. Polymerization
Polymerization is a chemical process in which small
molecules called monomers join together to form larger
molecules known as polymers. This process typically occurs
through a series of reactions in which the multiple
monomers bond to each other, forming a repeating
structural unit in the polymer chain. Polymerization can
occur through various mechanisms, including addition
(chain-growth) polymerization and condensation (step-
growth) polymerization. The resulting polymers have
diverse properties and applications, ranging from plastics
and resins to fibers and elastomers.

3. CONDENSATION POLYMERIZATION
Monomers having reactive group will have to undergo
condensation reaction. During the reaction, simple
molecules like water, alcohol, ammonia are eliminated
with the formation of high molecular weight polymers.
Because the monomers have reactive group, the polymer
will also have reactive end groups. Presence of these end
groups is effective on the properties of the polymers. This
type of polymerization often occurs between two different
types of monomers that contain complementary functional
groups, such as a carboxylic acid and an alcohol (to form an
ester), or a carboxylic acid and an amine (to form an

4. amide). The polymers produced can be linear or branched,
and this process is used to make polymers like polyesters,
polyamides (nylons), and polyurethanes.
It is know as condensation polymerization or step - wise
polymerization

addition polymerization
There are certain other types of monomers which does not
have any reactive group. But the monomers have double
bonds which are capable of formation of free radicals. The
free radical formed is capable of opening another double

5. bond and add to it. In this way, the polymer can be formed
by Scission of the double bond in the monomer and without
elimination of the any molecules. Because the polymer is
formed with the addition of chain, the polymerization is
known as addition polymerization or chain growth
polymerization.

6. DRAWING and effects on fibre

The spinning operation i.e. melt-spinning, dry-spinning, and
wet-spinning convert the fiber forming polymer into fibers.
However, this fiber cannot be used as a textile fiber
because of its low tenacity, high elongation at break, high
deformation even at a smaller load, low modulus, etc. So,
all the as spun fiber undergoes another operation i.e.
drawing which converts the fibers into textile fiber.

7. Drawing causes the following changes in a fiber.
Because of deformation, the length of the fiber
increased.
As a result, the diameter of the fiber decreased.
The molecular chain became more parallel along the
fiber axis, and so the orientation increased. Option D.
Due to high orientation, the drawn fiber shows higher
strength, higher modulus, and lower extension at
breakage.
Crystallinity may change in a direction i.e. it may
decrease, remain constant, or it may increase.

8. Why cupramonium rayon is not
commercially successful ?

Cupramonium rayon isn't very successful commercially
because:
Environmental Impact: Its production uses harmful
chemicals, which is bad for the environment.

Environmental and Safety Concerns: The production
of cupramonium rayon involves the use of copper and
ammonia in its manufacturing process, which can be

9. hazardous and environmentally damaging. These
substances need to be handled and disposed of
carefully, leading to higher safety standards and
environmental regulations that can increase production
costs and complexity.

High Costs: It's more expensive to make compared to
other similar fibers.

Competition: There are other fibers that are cheaper
and easier to produce.

10. Fewer Factories: There are not many places left that
make this type of rayon, making it harder to find.

Out of Fashion: It hasn't kept up with the latest
trends and demands from consumers for more eco-
friendly products.

11. When viscose rayon is wet, its tenacity is
reduced state its region

Viscose is a type of material made from cellulose, which is
quite disordered in its structure. This disordered (or
amorphous) structure means that the fibers are not very
strong and only have moderate strength because they can't
form many strong bonds. When viscose gets wet, it
becomes even weaker because water molecules can easily
get into the material. These water molecules push the
cellulose chains apart, breaking many of the weak bonds
that were holding the fibers together, which makes the

12. material half as strong when it's wet compared to when it's
dry

Polynoisic rayon shows better
properties over viscous rayon. State its
reason.

Polynosic rayon has a higher degree of crystallinity than
viscose rayon. This means that its polymer chains are better
aligned and more tightly packed together. This structure
gives it stronger internal cohesion and stability. Because of

13. its crystalline nature, polynosic rayon doesn't absorb water
as easily as the more amorphous viscose rayon. Water
molecules find it harder to penetrate between the tightly
packed polymer chains. Due to fewer water molecules
entering its structure, polynosic rayon retains more of its
strength when it is wet compared to viscose rayon. In
viscose, water breaks many hydrogen bonds, weakening
the material, but this happens less in polynosic.

14. Why moisture regain of polyester fiber
is very low?

Polyester fiber has a very low moisture regain primarily
because its chemical structure is hydrophobic, meaning it
naturally repels water. Additionally, the tightly packed and
non-polar nature of the polyester molecules leaves little
space for water to penetrate or bind, resulting in minimal
absorption of moisture. This makes polyester quick-drying
and resistant to water absorption.

15. DEFINE CHLORO FIBRE

Chlorofiber, often referred to as “chlorinated fiber”, is a
type of synthetic textile fiber which has been treated or
modified with chlorine. This treatment alters the fiber's
properties, making it resistant to fire, shrinkage, and
microbial degradation, among other benefits. The most
commonly known chlorofiber is a chlorinated polyvinyl
chloride fiber, typically abbreviated as **PVC**.

16. PROPERTIES OF CHLOROFIBER:

Fire Resistance: Chlorofibers are highly valued for
their flame retardant properties. The chlorine content in
the fibers contributes to their ability to self-extinguish
when removed from a flame source.

Chemical Resistance: These fibers are resistant to
most chemicals, making them suitable for use in
industrial applications where chemical exposure is
frequent.

17. Durability: The strength and durability of chlorofibers
make them suitable for products that require long-
lasting wear.

Mildew and Microbial Resistance: Chlorine
treatment provides excellent resistance to mildew and
microbial growth, which is beneficial for outdoor and
marine applications.

18. Applications:
Protective Clothing: Due to their fire-resistant
properties, chlorofibers are often used in protective
clothing for firefighters, industrial workers, and in other
environments where exposure to fire is a risk.
Upholstery Fabrics: The chemical and microbial
resistance of chlorofibers makes them ideal for
upholstery fabrics that need to withstand harsh
conditions, such as those used in outdoor, healthcare,
and public transport settings.
Industrial Uses: Chlorofibers are used in various
industrial applications, including filters, hoses, and

19. components for automotive and machinery, where
resistance to chemicals and heat is necessary.

20. Define bi- components fibre

Bicomponent fibers are a type of synthetic fiber engineered
by combining two distinct polymers within a single filament.
These fibers leverage the properties of two different
materials in a way that one single fiber type cannot,
enabling manufacturers to tailor the fibers to meet specific
needs. Bicomponent fibers are commonly used in textiles,
automotive applications, hygiene products, and various
other industries where specific functional properties are
desired.

21. Explain the characteristics of
fibre forming polymers

HYDROPHILIC PROPERTIES

Fibre polymers should be hydrophilic. This means that the
polymers should be polar, enabling them to attract water
molecules. A fibre is comfortable to wear if its polymer

22. system consists of hydrophilic polymers, and the system
itself permits the entry of water molecules.

CHEMICAL RESISTANCE

Fibre polymers should be chemically resistant for a
reasonable length of time against the degrading agents
such as sunlight and weather, common types of soiling,
body exudations, laundry liquors and dry cleaning solvents.
Chemically resistant polymers should also not be toxic or

23. hazardous to wear against human skin; this is a most
important requirement which is usually taken for granted.


LINEARITY

Fibre polymers be linear (i.e. the polymers should not be
branched; sec also Fig. 1.11). As explained in 5 below, only
linear allow adequate polymer alignment to bring into
effect sufficient inter-polymer forces of attraction to give a
cohesive polymer system and, hence, useful textile fibre.

24. LENGTH:

The polymer chain must be longer to achieve more
strength in the fiber by holding the crystalline regions
together. A polymer length of 100 nanometers is
required to produce a fiber with adequate strength.


ORIENTATION:

The polymers must be capable of being oriented. A
high degree of orientation gives a great tensile strength

25. in the fiber. There are two forms of polymer orientation.
They are amorphous and crystalline. In the operation
of drawing, which stretches the extruded and
coagulated filament causes the polymers to orient
themselves.

HIGH MELTING POINT

The fibers must have high melting point to withstand
the extreme heat conditions and it needs to be above
2250 c for the usage of apparel and textile
manufacturing.

26. IMPORTANCE OF SPIN FINISH ON TEXTILE
FIBRE

A spin finish is a special coating added to synthetic fibers
during their production. It serves multiple purposes: it
reduces friction to prevent damage while the fibers move
through machinery, enhances fiber handling, prevents
static build-up, and improves the overall performance of
the fibers in textile manufacturing. The composition of a
spin finish can include lubricants, antistatic agents, and
other additives tailored to specific needs, ensuring fibers

27. are well-prepared for their final use in various textile
products.

28. Molecular weight distribution
and its effect on fibre
Molecular weight distribution (MWD) refers to the variation
in molecular weights within a sample of a polymer, such as
synthetic textile fibers. In simpler terms, it's a way to
describe how much the polymer molecules differ in size
(length) within a given batch of material.
MWD is typically represented by measures such as:
Number-average molecular weight (Mn): The total
molecular weight of the polymer divided by the total
number of molecules.

29. IMPORTANCE IN TEXTILE FIBER FORMATION:

Mechanical Properties: The mechanical properties of fibers
such as strength, elasticity, and toughness are influenced by
the molecular weight and its distribution. Higher molecular
weights typically contribute to stronger, more durable
fibers, but very high molecular weights can make
processing difficult.
Dyeing and Finishing: The behavior of fibers during dyeing
and finishing processes can be affected by MWD. Fibers
with a broader molecular weight distribution might display

30. uneven dye uptake, leading to inconsistent color and
appearance and it also causes the change in thermal
properties.

31. DEFINE TOW AND TOP
In the textile industry, the terms "tow" and "top" refer to
specific forms of fiber preparations, primarily used in the
context of processing staple fibers, which are fibers of a
limited or cut length, as opposed to continuous filaments.
Here’s a breakdown of each term:

Tow
Tow refers to a bundle of continuous filament fibers which
have not been cut into staple fibers. It is usually created
during the production of man-made fibers like acrylic,

32. nylon, or polyester. These continuous filaments are drawn
together in a loose, rope-like form. Tow can be processed
further into staple fibers by cutting it into shorter lengths,
which are then ready to be spun into yarn. Tow is typically
used in applications requiring bulk fiber processing, such as
in the manufacture of bulkier yarns or nonwoven fabrics.

Top

Top is a term used in the processing of wool and other
staple fibers. It represents a continuous sliver of combed

33. fibers, with most of the short fibers and impurities
removed, and the remaining fibers lying parallel to each
other. The top is an intermediate product that is very
uniform in thickness and is prepared specifically for
spinning into smoother, finer, and higher-quality yarns. The
combing process that produces top aligns all fibers in a
parallel arrangement, enhancing the strength and
uniformity of the spun yarn.

34. TOW TO TOP CONVERSION
The term "tow to top conversion" refers to a specific
process in the textile industry where tow (a bundle of
continuous synthetic filaments) is converted into top (a
sliver of aligned, combed staple fibers). This process is
predominantly used with synthetic fibers like polyester,
nylon, and acrylic, and is crucial for producing materials
that mimic the properties of natural fibers like wool.

STEPS IN TOW TO TOP CONVERSION BY CUTTING
METHOD

35. Cutting:
The first step in converting tow to top is to cut the
continuous filament tow into staple fibers of desired
lengths. This length typically matches the staple length of
natural fibers used for spinning yarns.

Blending:
The cut staple fibers can be blended with natural fibers
(such as wool or cotton) or other synthetic fibers to achieve
specific qualities in the yarn, such as strength, texture, or
cost efficiency.

36. Carding:
The blended fibers are then processed through a carding
machine. Carding disentangles, cleans, and intermixes
fibers to produce a continuous web or sliver that is uniform
in thickness.

Combing:
This optional step further refines the fiber by removing
shorter fibers and aligning the remaining fibers more
parallel to each other. Combing produces a higher quality
sliver (or top), which is finer and more suitable for spinning
into smooth, strong yarns.

37. Drawing:
The sliver is then drawn, which involves stretching and
further aligning the fibers to ensure uniformity in thickness
and strength. This step may be repeated multiple times to
enhance the alignment and cohesion of the fibers.
The key aspects of converting synthetic filament tow into
staple fiber top using the cutting method, stretch breaking
method, and perlock method.

38. 1. Cutting Method

Process: The cutting method involves directly cutting
continuous filament tow into specific lengths of staple
fibers using precision cutting machines.

Steps:
Feeding: The tow is spread and untangled.
Cutting: Filaments are cut uniformly at desired lengths.

39. Processing: Fibers may be carded and combed to improve
alignment.

Advantages:
- Precise control over fiber length.
- Simplicity and cost-effectiveness in processing.

Applications: Used where fiber uniformity and length are
critical, suitable for standardized textile production.

40. 2. Stretch Breaking Method

Process: This method stretches the tow until fibers break at
their weakest points, creating staple fibers of varying
lengths, which helps mimic the natural variability found in
natural fibers.

Steps:
Feeding and Stretching: Tow is stretched to align fibers and
induce stress.

41. Breaking: Continued stretching breaks the fibers unevenly,
based on inherent weak points.
Crimping: Fibers are crimped to add bulk and texture.
Further Processing: Fibers are carded and combed to
enhance alignment.

Advantages:
- Produces fibers with natural-like variability.
- Enhances the feel and bulk similar to natural fibers.

42. Applications: Ideal for textiles that require a natural feel,
such as apparel and upholstery.

3. Perlock Method

Process: A combination of chemical and mechanical
processes where tow is chemically treated to enhance
flexibility and then mechanically crimped and cut into
staples.

43. Steps:
Chemical Treatment: Tow is treated to partially dissolve or
swell the fibers, reducing their diameter.
Mechanical Processing: Fibers are crimped and then cut to
desired staple lengths.
Carding and Combing: Further processing to improve fiber
alignment and consistency.

Advantages:
- Produces soft, wool-like textures in synthetic fibers.

44. - Allows for the customization of fiber properties through
chemical treatment.

Applications: Frequently used for acrylic and other
synthetic fibers aimed at replicating the softness and
warmth of natural wool.