There
are many primary properties necessary for a polymeric material to form an
adequate fiber:
1.
Fiber length to breadth ratio
2.
Fiber uniformity
3.
Fiber strength and adaptability
4.
Fiber extensibility and
elasticity
5.
Fiber cohesiveness
Certain
alternative fiber properties increase its value and desirability in its
supposed end-use; however aren't necessary properties essential to form a
fiber. Such secondary properties embrace moisture absorption characteristics,
fiber resiliency, abrasion resistance, density, luster, chemical resistance,
thermal characteristics, and flammability. An additional careful description of
both primary and secondary properties follows in Secs. 1 and 2
1. Primary
Properties
Fiber Length to dimension ratio.
Fibrous materials should have sufficient length so they will be created into
twisted yarns. Additionally, the breadth of the fiber (the diameter of the
cross-section) should be a lot of but the general length of the fiber;
sometimes the diameter ought to be 1/100 of the length. The fiber could also be
"infinitely" long, as found with continuous filament fibers, or as
short as 0.5 inches (1.3 cm), as found in staple fibers. Most natural fibers
are staple fibers, whereas synthetic fibers come in either staple or filament
type, looking on process before Yarn formation.
Fiber Uniformity.
Fibers appropriate for process into yarns and fabrics should be fairly uniform
in form and size. while not sufficient
uniformity of dimensions and properties during a given set of fibers to
be twisted into yarn, the particular formation of the yarn could also be not
possible or the ensuing yarn could also be weak, rough, irregular in size and
form, and unsuitable for textile usage. Natural fibers should be sorted and
ranked to assure fiber uniformity, whereas synthetic fibers could also be
"tailored" by cutting into acceptable uniform lengths to offer a
correct degree of fiber uniformity.
Fiber Strength and adaptability.
A fiber or yarn made of the fiber should possess sufficient strength to be
processed into a textile material or alternative textile article. Following
fabrication into a textile article, the ensuing textile should have sufficient
strength to produce adequate sturdiness during end-use. Several specialists
take into account single fiber strength of 5 grams per denier to be necessary
for a fiber to be appropriate inmost textile applications, though bound fibers
with strengths as low as 1.0 gram per denier are found appropriate for a few
applications.
The
strength of a single fiber is termed the determination, outlined because the
force per unit linear density necessary to interrupt a noted unit of that
fiber. The breaking determination of a fiber could also be expressed in grams
per denier (g/d) or grams per tex (g/tex). Each denier and tex are units of
linear density (mass per unit of fiber length) and are outlined because the
variety of grams of fiber activity 9,000 meters and 1,000 meters, severally. As
a result, the denier of a fiber or Yarn can invariably be nine fold the tex of
constant fiber. Since tenacities of fibers or yams are obtained by dividing the
force by denier or tex, the determination of a fiber in grams per denier are
going to be 1/9 that of the fiber determination in grams per tex.
As
a result of the variation of the metric system of Units (SI), the suitable
length unit for breaking determination becomes kilometer (km) of breaking
length or Newton per tex (N/tex) and can be equivalent in worth to g/tex.
The
strength of a fiber, Yarn, or material is expressed in terms of force per unit
space, and once expressed during this manner, the term is strength. the
foremost common unit employed in the past for strength has been pounds force
per area unit or grams force per square metric linear unit. In SI units, the
pounds force per square inch x 6.895 can become kilopascals (kPa) and grams
force per square metric linear unit x 9.807 can become megapascals (MPa). A
fiber should be sufficiently versatile to travel through perennial bendings
while not vital strength deterioration or breakage of the fiber. while not
adequate flexibility, it'd be not possible to convert fibers into yarns and
materials, since flexing and bending of the individual fibers could be a
necessary a part of this conversion. Additionally, individual fibers during a
textile are going to be subjected to hefty bending and flexing throughout
finish use.
Fiber Extensibility and snap.
A private fiber should be ready to endure slight extensions long (less than 5%)
while not breakage of the fiber. At constant time, the fiber should be ready to
virtually utterly recover following slight fiber deformation. In alternative
words, the extension deformation of the fiber should be nearly elastic. These
properties are necessary as a result of the individual fibers in textiles are
usually subjected to sudden stresses,
and also the textile should be ready to offer and recover while not vital
overall deformation of the textile.
Fiber Cohesiveness.
Fibers should be capable of adhering to at least one another once spun into a
yarn. The cohesiveness of the fiber could also be thanks to the form and
contour of the individual fibers or the character of the surface ofthe fibers.
Additionally, long-filament fibers by virtue of their length are twisted along
to relinquish stability while not true cohesion between fibers. Usually the
term "spinning quality" is employed to state the general
attractiveness of fibers for each other.
2. Secondary
Properties
Moisture Absorption and natural
action. Most fibers tend to soak up wetness
(water vapor) once up-to-date with the atmosphere. The number of water absorbed
by the textile fiber depends on the chemical and body and properties of the
fiber, moreover because the temperature and humidness of the environment. The
share absorption of vapor by a fiber is usually expressed as its wetness
regain. The regain is set by consideration a dry fiber, then inserting it
during a space set to straightforward temperature and humidness [21° f 1°C and 65th ratio (RH)] are ordinarily
used). From these measurements, the share wetness regain of the fiber is set.
 |
Figure: Equations |
Percentage
moisture content of a fiber is that the percentage of the overall weight of the
fiber, that is attributable to the moisture present, and is obtained from the
subsequent formula.
The
percentage moisture content can always be the smaller of the 2 values.
Fibers
vary greatly in their regain, with hydrophobic (water-repel-ling) fibers having
regains close to zero and hydrophilic (water-seeking) fibers like cotton,
rayon, and wool having regains as high as 15 august 1945 at 21°C and 65th RH.
The flexibility of fibers to regain massive amounts of water affects the
essential properties of the fiber in finish use. Absorbent fibers are able to
absorb massive amounts of water before they feel wet, a very important issue
wherever absorption of perspiration is important. Fibers with high regains are
easier to method, finish, and dye in liquid solutions, however can dry a lot of
slowly. The low regain found for several synthetic fibers make them fast
drying, a definite advantage in bound applications. Fibers with high regains
are usually fascinating as a result of the supply a "breathable"
fabric which might conduct moisture from the body to the skin atmosphere
without delay, because of their favorable moisture absorption-desorption
properties. The tensile properties of fibers similarly as their dimensional
properties are suffering from moisture.
Fiber Resiliency and Abrasion
Resistance. The power of a fiber to soak up shock
and recover from deformation and to be generally immune to abrasion forces is
very important to its end-use and wear characteristics. In client use, fibers
in materials are usually placed below stress through compression, bending, and
twisting (torsion) forces below a range of temperature and humidity conditions.
If the fibers among the material possess smart elastic recovery properties from
such deformative actions, the fiber has smart resiliency and higher overall look
in finish use. As an example, wool shows poor wrinkle recovery beneath hot wet
conditions, whereas polyester exhibits smart recovery from deformation as a
results of its high resiliency. Resistance of a fiber to break once mobile
forces or stresses are available in contact with fiber structures is remarked
as abrasion resistance. If a fiber is ready to effectively absorb and dissipate
these forces while not harm, the fiber can show smart abrasion resistance. The
toughness and hardness of the fiber is expounded to its chemical and physical
structure and also the morphology of the fiber, and can influence the abrasion
of the fiber. A rigid, brittle fiber like glass, that is unable to dissipate
the forces of abrasive action, ends up in fiber harm and breakage, whereas a
tricky, but a lot of plastic, fiber like polyester shows higher resistance to
abrasion forces. Finishes will have an effect on fiber properties as well as
resiliency and abrasion resistance.
Luster.
Luster refers to the degree of sunshine that's mirrored from the surface of a
fiber or the degree of gloss or refulgence that the fiber possesses. The
inherent chemical and physical structure and form of the fiber will have an
effect on the relative luster of the fiber. With natural fibers, the luster of
the fiber relies on the morphological kind that nature offers the fiber,
although the relative luster may be modified by chemical and/or physical
treatment of the fiber in processes, like mercerization of cotton. Synthetic
fibers will vary in luster from bright to uninteresting counting on the number
of delusterant added to the fiber. Delusterants like titanium dioxide tend to
scatter and absorb light-weight, thereby creating the fiber seem duller. The
desirability of luster for a given fiber application can vary and is commonly
hooked in to the supposed finish use of the fiber during a cloth and on current
fashion trends.
Resistance to Chemicals within
the atmosphere. A textile fiber, to be helpful,
must have affordable resistance to the chemicals it comes in reality within its
atmosphere during use and maintenance. It should have resistance to oxidation
by oxygen and different gases within the air, significantly within the presence
of light, and be resistant to attack by microorganisms and different biological
agents. Several fibers bear light-induced reactions, and fibers from natural
sources are at risk of biological attack, however such deficiencies may be
reduced by treatment with applicable finishes. Textile fibers are available in
contact with an oversized vary of chemical agents during washing and dry
cleaning and should be immune to attack below such conditions.
Density.
The density of a fiber is related to its inherent chemical structure and also
the packing of the molecular chains among that structure. The density of a
fiber can have a comprehensible impact on its aesthetic appeal and its quality
in given applications. As an example, glass and silk fabrics of a similar
denier would have noticeable variations in weight because of their broad
variations in density. Fishnets of polypropylene fibers are of nice utility as
a result of their density is a smaller amount than that of water. Densities are
typically expressed in units of grams per cubic centimeter; however in Si units
are going to be expressed as kilograms per cubic meter, which gives a price one
thousand times larger.
Thermal and Flammability
Characteristics. Fibers utilized in textiles
should be proof against wet and dry heat, should not ignite pronto once coming
back in contact with a flame, and ideally should self-extinguish once the flame
is removed. Heat stability is especially necessary to a fiber throughout dyeing
and finishing of the textile, and through cleanup and general maintenance by
the buyer. Textile fibers for the most half are created of organic polymeric
materials containing carbon and burn on ignition from a flame or alternative
propagating source. The chemical structure of a fiber establishes its overall
flammability characteristics, and applicable textile finishes will reduce the
degree of flammability. Variety of federal, state, and native statutes
eliminate the foremost dangerous flammable fabrics from the marketplace.
3. Primary
Fiber Properties from an Engineering Perspective
The
textile and polymer engineer should consider variety of criteria essential for
formation, fabrication, and assembly of fibers into textile substrates. Often,
the factors used are going to be just like those set forth regarding end-use
properties. Ideally, a textile fiber should have the following properties:
1.
A melting and/or decomposition
point higher than 220°C.
2.
A tensile strength of 5 g/denier
or greater.
3. Elongation at break higher than
100% with reversible elongation up to 5 strains.
4.
A moisture absorption factor of
2%-5% moisture uptake.
5.
Combined moisture regains and air
entrapment capability.
6.
High abrasion resistance.
7.
Resistance to attack, swelling,
or solution in solvents, acids, and bases.
8.
Self-extinguishes once removed
from a flame.
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