Properties of Textile Fiber
Textile Fiber :A unit of matter, either natural or manufactured, that forms the basic element of fabrics and other textile structures. A fiber is characterized by having a length at least 100 times its diameter or width. The term refers to units that can be spun into a yarn or made into a fabric by various methods including weaving, knitting, braiding, felting, and twisting. The essential requirements for fibers to be spun into yarn include a length of at least 5 millimeters, flexibility, cohesiveness, and sufficient strength. Other important properties include elasticity, fineness, uniformity, durability, and luster.
Properties of Fiber :We saw three types of properties according to the fiber properties for a textile fiber. There are a lot of characteristic in the textile fibers. But it is characterized as three basic characterization.
They are
A) Physical Properties
B) Mechanical Properties
C) Chemical Properties
A) Physical Properties
1. Length ------Staple (15mm - 150 mm) 2 .Fineness ------Length : Width = 1000:1 3. Crimp 4. Maturity
5. Lusture 6. Softness
7. Resiliency 9. Density
10. Appearance 11. Flexibility
12. Toughness 13. Elorgation
14.Cross Sectional Shape
B)Mechanical Properties
1. Strength (Tenacity) (P.S.I)
2. Elasticity (Recovery percentage)
3. Extensibility (Breaking Extension)
4. Rigidity (Stiffness)
C) Chemical Properties
1. Solubility in aqueous salt
2. Solubility in organic salt
Useful properties of another hind desired in a textile fiber are indicated bellow.
- Behavior towards dyes.
- Ability to moisture absorption
- Resistance to deteriorating influence including; light, thermal stability, resistance to bacteria, mildow moth and other destructive insect, corrosive chemicals.
Without above that properties fiber has also
1. Thermal Prperties
2. Torsional Properties
Mechanical Properties of Textile Fibers
A. Tensile Properties.
B. Flexural Properties.
C. Torsional Properties.
D. Fictional Properties
A. Tensile Properties.Tensile properties indicates how a material will react to the forces being applied in Tension. Fibers usually experience tensile loads whether they are used for apparel or technical structures. Their form, which is long and fine, makes them some of the strongest materials available as well as very flexible. This book provides a concise and authoritative overview of tensile behaviour of a wide range of both natural and synthetic fibres used both in textiles and high performance materials.
Tensile Properties of Textile Material
1. Tenacity 2. Breaking extension 3. Work of rupture
4. Initial modulus 5. Work factor 6. Work recovery
7. Elastic recovery 8. Yield stress 9. Yield strain
10.Yield point 11. Breaking load 12. Creep
1. Tenacity:The ratio of load required to break the specimen and the linear density of that specimen is called tenacity.Mathematically, Tenacity = Load required to break the specimen / Linear density of the specimenUnit: gm/denier, gm/Tex, N/Tex, CN/Tex etc.
2. Breaking extension:The elongation necessary to break a textile material is a useful quantity. It may be expressed by the actual percentage increase in length and is termed as breaking extension.Mathematically, Breaking extension (%) = (Elongation at break / Initial length) × 100%
3. Work of rupture: Work of rupture is defined as the energy required to break a material or total work done to break that material. Unit: Joule (J)
4. Initial modulus:The tangent of angle between the initial curve and the horizontal axis is equal to the ratio of stress and strain.
In engineering science the ratio is termed as Young’s Modulus and in textile we use the terms as Initial Young’s Modulus.
Initial modulus, tan α = stress / strain Tan α ↑↓ → extension ↓↑
5. Work factor:The ratio between work of rupture and the product of breaking load and breaking elongation is called work factor. Work factor = work of rupture / (breaking load × breaking elongation)
6. Work recovery: The ratio between work returned during recovery and total work done in total extension is called work recovery.Total extension = Elastic extension + Plastic extension Total work = work required to elastic extension + work required to plastic extension.
7. Elastic recovery:The power of recovery from a given extension is called elastic recovery. Elastic recovery depends on types of extension, fiber structure, types of molecular bonding and crystalline of fiber. The power of recovery from a given extension is called elastic recovery. Elastic recovery depends on types of extension, fiber structure, types of molecular bonding and crystalline of fiber.
8. Yield point.The point up to which a fiber behaves elastic deformation and after which a fiber shows plastic deformation is called yield point.
9. Yield stress:The stress at yield point is called yield stress.
10. Yield strains:The strain at yield point is called yield strain.
11. Breaking load:The load which is required to break a specimen is called breaking load.
12. Creep: When a load is applied on the textile material an instantaneous strain is occurred, but after that the strain will be lower with the passing time. This behavior of the material is termed as creep.
There are two types of creep:
i. Temporary creep
ii. Permanent creep
B. Flexural Properties.
Flexural properties is one of the mechanical properties of textile material. It is the property or behaviour shown by the fibre or material when we bend it. The importance of Flexural properties is required when we wear cloth. The flexural test measures the force required to bend a beam under three point loading conditions. The data is often used to select materials for parts that will support loads without flexing. Flexural modulus is used as an indication of a material’s stiffness when flexed.
Flexural Property of Textile Material
The behavior which shows by textile material during bending is called flexural property.
1. Flexural rigidity
2. Bending recovery
3.Bendingmodulus
1. Flexural rigidity:
Flexural rigidity is the stiffness of a textile fiber. It can be defined as the couple needed to bend a fiber.Mathematically, Flexural rigidity = (1/4π) (ηET2/ρ)
Where,
η = shape factor,
E = specific shear modulus,
T =linear density (Tex),
ρ = density (gm/cm3)
Specific flexural rigidity:
Specific flexural rigidity can be defined as the flexural rigidity of linear density.
Mathematically, Specific flexural rigidity = (1/4π)(ηE/ρ)
Where,
η = shape factor,
E = specific shear modulus,
ρ = density (gm/cm3)
2. Bnding recovery:
The recovery from a given curvature is called bending recovery.Say, nylon shows 100% recovery from small curvature of 15D, where it shows 20% recovery from large curvature.
Unit = N-m2/ Tex.
3. Shape factor:
Shape factor is a number that indicates the shape of a fiber. Shape is expressed by “η”.If, η = 1, it indicates the shape of fiber is round.
If,
η > 1, it indicates the shape of fiber is increased.If,
η < 1, it indicates the shape of fiber is decreased.
C. Torsional Properties.
The behaviors which are shown by a textile material when it is subjected to a torsional force is called torsional property. It is the property of fibre or material when a Torsional force is applied on it. Here Torsional force is a twisting force that is applied on the two ends of the material in two opposite direction.
It is the property of fibre or material when a Torsional force is applied on it. Here Torsional force is a twisting force that is applied on the two ends of the material in two opposite direction. The behaviors which are shown by a textile material when it is subjected to a torsional force is called torsional property.
1. Torsional rigidity
2. Breaking twist
3. Shear modulus
1. Torsional rigidity:
Torsional rigidity can be defined as the torque required against twisting is done for which torque is termed as torsional rigidity.Mathematically, torsional rigidity = ηET2/ρ
Where,
η = shape factor,
E = specific shear modulus (N/tex)
Specific torsional rigidity: Specific torsional rigidity can be defined as the torsional rigidity of a fiber of unit linear density.Mathematically, specific torsional rigidity = ηE/ρ
Unit: N-m2 /Tex
2. Breaking twist:
The twist for breaking of a yarn is called breaking twist. It also can be defined as the number of twists required to break a yarn. Breaking twist depends on the diameter of fiber and it is inversely proportional to its diameter.That is, Tb ∞ 1/d
Where,
Tb = Breaking twist,
d = diameter of fiber
Breaking twist angle: This is the angle through which outer layer of fiber are sheared at breaking. Mathematically, α = tan-1(πdTb)
Where,
α = breaking twist angle,
d = diameter of fiber,
Tb = breaking twist per unit length
D. Fictional Properties
Frictional properties is due to the friction between the fibres. This properties are shown during processing. Too high friction and too low friction is not good for yarn. Therefore it is an important property when yarn manufacturing and processing.
When the textile materials are processed, then friction is developed between the fibers. The properties which are shown by a textile material during friction is known as frictional property. This properties are shown during processing. Too high friction and too low friction is not good for yarn. Therefore it is an important property when yarn manufacturing and processing.
Frictional properties depend on-
1. Composition of the material
2. State of the surface of the material
3. Pressure between the surfaces
4. Temperature
5. Relative humidity %
Co-efficient of friction: Frictional force is proportional to the normal or perpendicular of a material due to its own weight.That is, F ∞ N Or, F = μ N Or, μ = F/NWhere, F = Frictional force, N = Normal / perpendicular forceHere, μ is the proportional constant known as “co-efficient of friction”.So, co-efficient of friction can be defined as the ratio of frictional force and perpendicular force.
Methods of measuring co-efficient of friction:
Capstan method is most commonly used to measure co-efficient of fraction. Capstan method can be classified into two classes-
1. Static capstan method
2. Dynamic capstan method
Other methods-
1. Buckle & Pollitt’s method
2. Abboh & Grasberg method
3. GuthericOlivers method
Influences of friction on textile material:
Friction holds the fibers in a sliver and hence the sliver does not break due to its’ own weight. Friction helps in drafting and drawing.· Uniform tension can be maintained during winding & warping because of friction.· Friction helps to make yarn by twisting during spinning.· Friction increases lusture and smoothness of the yarn and the fabric.· Friction makes more clean material.
Demerits of friction on textile material:·
Friction causes nap formation.· High static friction causes high breakage of yarn during weaving.· If the frictional force is high, the handle properties of fabric will be low.· Friction generates temperature and therefore static electricity is developed which attracts dust, dirt etc. and the materials become dirty.· Sometimes due to over friction materials may be elongated.· Friction increases yarn hairiness.· Friction worn out parts of machine.
Minimization of friction intensity:
1. Sizing is done in warp yarn before weaving to reduce frictional intensity. As a result, yarn damage will be reduced.
2. Emulsion, oil, lubricants etc. are specially applied on jute fiber to reduce friction.
3. Chemical treatment is done on wool fiber to reduce scale sharpness and thus reduce friction during processing.
4. By calendaring frictional intensity of cloth is reduced.
5. Sometimes resin finish is applied on fabric to reduce friction.
Cotton Fiber:
Among the seed and fruit fibres, cotton has grown in stature as the most important textile fibre in the world. In fact, cotton is the backbone and basic foundation of the world’s textile trade and industry. Cotton is a natural vegetable fibre produced in the cotton plant in many countries of the world even in Bangladesh also.
Properties of Cotton Fibres:
Properties of cotton fiber can be divided into two parts, one is according to physical structure and another is using process.
A. According to physical structure:
Length of cotton fiber:
Physically the individual cotton fibres consist of a single long tubular cell. Its length is about 1200-1500 times than its breadth. Length of cotton fibre varies from 16mm to 52 mm depending upon the type of cotton.
- Indian cotton- 16-25 mm
- American cotton- 20-30 mm
- Sea Island- 38-52 mm
- Egyptian cotton- 30-38 mm
Fineness of cotton fiber:
Longer the fibre, finer the fibre in case of cotton fibre. It is expressed in term of decitex and it varies from 1.1 to2.3 decitex.
- Indian= 2.2-2.3dtex
- American= 2.1-2.2 dtex
- Egyptian= 1.2-1.8 dtex
- Sea Island= 1.0-1.1 dtex
Fineness may be more in case of immature fibre. So it is necessary to express maturity with fineness.
Strength and extension of cotton fiber:
Cotton fibre is fairly among natural fibres in relation to tenacity which is 3-3.5g/dtex. Its tensile strength is between wool and silk fibre but disadvantage is low extension at break which is 5-7%.
Elastic properties of cotton:
Recovery from deformation of cotton fibre, yarn or fabric from applied load is very low. By applying heat it can’t be achieved. This property can be achieved by -1.Chemical treatment to improve crease recovery, but the problem is the materials become harsher due to chemical treatment 2. blending or mixing of cotton with elastic fibre, e.g. polyester, blend ratio depends on the end use of the fabric. The initial modulus is fairly high=0
5 g/dtex (wool=0.25 g/dtex)
Cross-section:
Cross-section of cotton fibre is some what ribbon like. The cell wall is rather thin and the lumen occupies about two-third of the entire breadth and shows up very prominent in polarized light. Fibre cross-section becomes round when mercerized.
Appearance:
Cotton fibre is fairly short, fine and creamy white color. Color of the fibre depends on soil of growth. By adding chemicals in the soil, color of the cotton fibre may be varied.
Crimp:
Cotton fibre is more or less twisted on its longitudinal axis which cab not be seen from out side is called convolution. The twist in the fibre does not to be continuous in one direction i.e. if at first right direction, then left direction. This property of cotton fibre helps in spinning.
B. According to using process:
Comfortable:
Cotton fiber has large amorphous portion and this is why the air can be in and out through cotton fiber. So, the fabric made by cotton fiber is quite comfortable to use.
Soft Hand:
Cotton fiber is too much regular fiber and if properly ginned; this fibre can be the best soft hand feeling fibre amongst the others.
Absorbent:
Cotton fiber has high absorbency power and this is why this fiber can be died properly and without any harassment.
Good Color Retention:
If the printing is applied on cotton fiber, it seems it doesn’t spread the color outside the design. So printing efficiency is good on cotton fibre.
Machine Washable & Dry Cleanable:
It is seen that some fibers can’t be dried or washed due to it’s sensitivity and weak fastness properties but in case of Cotton fiber you will have large number of options to choose. You can easily wash the cotton made fabric by machines and even you will be able to dry this fiber by using electronic drier.
Good Strength:
If you want to seek an average strength which might be enough for you; then cotton fiber can be your ultimate choice. The strength of cotton fiber is quite good.
Cotton Fibre Drapes Well:
The drape-ability of cotton fibre is awesome. You can use the cotton fibre made fabric in any kind of wear which needs more flexibility and drapes.
Sewing & Handling Is Easy:
The sewing efficiency on Cotton made fabric is easier and comfortable than other fiber. This is why the demand of cotton made fabric is higher in all over the world.
Uses of Cotton Fiber:
Cotton fiber is a versatile fibre which has wide variety of uses. But the Cotton fibre is mostly used on the Apparel Industry to make the wearing cloth like Sweaters, Skirts, Shirts, Swimwear, Kids wear, Blouses, Pants, Hosiery and to make other type of dresses.
Polyester Fiber
A manufactured fiber in which the fiber forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic units, p(-R-O-CO- C6H4-CO-O-)x and parasubstitutedhydroxy-benzoate units, p(-R-O-CO-C6H4-O-)x.
Polyester Fiber Characteristics
- Strong
- Resistant to stretching and shrinking
- Resistant to most chemicals
- Quick drying
- Crisp and resilient when wet or dry
- Wrinkle resistant
- Mildew resistant
- Abrasion resistant
- Retains heat-set pleats and crease
Physical Properties of Polyester: Like cotton or other fiber, polyester fiber consists of some important physical properties. Important physical properties of polyester are given below.
- Tenacity: 5 – 7 gm/den
- Elongation at break: 15 – 30%
- Elastic modulus: 90
- Elasticity: Good
- Moisture Regain (MR%): 0.40%
- Specific Gravity: 1.38
- Melting point: 2500C
- Volumetric Swelling: None
- Ability to protest friction: Excellent
- Color: White
- Light reflection ability: Good
- Lusture: Bright
Chemical Properties of Polyester: Various types of chemical properties of polyester fiber are given below:
- Acids: Good resistance to acids in cold condition. But polyester degrades by H2SO4 at high temperature.
- Basic: Good resistance to basic in cold condition but Strong NaOH dissolves polyester in boiling.
- Effect of bleaching: Polyester does not affected by bleaching process.
- Organic solvent: Organic solvent does not affect on polyester fiber.
- Protection ability against mildew: Good
- Protection ability against insects: Good
- Dyes: Polyester could be dye with disperse, azoic color and some pigments.
- Solvents of polyester: Following are the solvents of polyester:
- Chlorinated hydrocarbon.
- F3COOH
- Phenol (in hot condition)
So, during processing of polyester, we have to consider the physical and chemical properties of polyester.
- Easily washed
Polyester Fiber Properties - Tensile Properties
Polyester fibers are available in 4 tenacity levels.
Low pill fibres- usuall in 2.0 / 3.0 D for suiting enduse with tenacities of 3.0 to 3.5 gpd(grams per denier). These fibres are generally used on worsted system and 1.4D for knitting
Medium Tenacity - 4.8 to 5.0 gpd
High Tenacity - 6.0 to 6.4 gpd range and
Super high tenacity - 7.0 gpd and above
Both medium and high tenacity fibres are used for apparel enduse. Currently most fibre producers offer only high tenacity fibres. Spinners prefer them since their use enables ring frames to run at high speeds, but then the dyeablity of these fibres is 20 to 25% poorer, also have lower yield on wet processing, have tendency to form pills and generally give harsher feel.
The super high tenacity fibres are used essentially for spinning 100% polyester sewing threads and other industrial yarns. The higher tenacities are obtained by using higher draw ratios and higher annealer temperatures upto 225 to 230 degree C and a slight additional pull of 2% or so at the last zone in annealing.