Frictional Property of Textile Fiber

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. Gutheric & Olivers 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.

Mechanical Properties of Textile Fibers | Mechanical Properties of Textile Materials

The mechanical properties of textile fibers include fiber strength, elongation, elasticity, abrasion resistance, modulus of elasticity. Fiber strength is the ability of fiber resistance to external damage, which largely determine the durability of the textile goods. Fiber strength is the absolute strength fibers to said fibers in a row it is under increasing load until fracture can bear the maximum load. Lecturer in units of its statutory Newton (N) or PCT Newton (cN). Over the past practice of using chocolate or kilograms force said.

Fiber strength with the thickness of fiber is related to the different thickness of the fiber so absolutely not comparable strength, so often used to indicate the relative strength of the fiber strength. Relative intensity is the unit linear density (per special or every once) fibers can bear the greatest tension. Legal units of measurement for the cow / special (N / tex), or determining cattle / Special (cN / tex). Over the past practice of using Chris / Dan said. The mechanical properties of Textile fibres is the response to applied forces and deformation. But we should know the strength of yarn can not be greater than the sum of the maximum strength of its component’s fibres.

Mechanical Properties of Textile Fibers

1. Tensile Properties.
2. Flexural Properties.
3. Torsional Properties.
4. Fictional Properties

1. 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.

2. 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.

3. 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.

4. 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.

Flexural Property of Textile Fiber

 Flexural properties is one of the mechanical properties of textile material. 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. Since the physical properties of many materials (especially thermoplastics) can vary depending on ambient temperature, it is sometimes appropriate to test materials at temperatures that simulate the intended end use environment.

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. Bending modulus

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

Tensile Properties of Textile Material ( Fiber or Yarn or Fabric ) | Tenacity | Breaking Extension | Work of Rupture | Initial Modulus | Work Factor | Work Recovery | Elastic Recovery | Yield Stress | Yield Strain | Yield Point | Breaking Load | Creep

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

Description of each is given below:

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

 

Here, AB = initial length of the specimen 

AD = final length after recovery 

BD = total extension 

CD = elastic extension 

BC = plastic extension 

Total extension = Elastic extension + Plastic extension
So,Elastic recovery (%) = (Elastic extension/total extension) ×100% = (CD/BD) × 100% 

So, Plastic recovery = (plastic extension/total extension) ×100% = (BC/BD) ×100%