Textile Fibers and Properties

Staple Fiber: Staple fibers are the fibers of limited strength (1-4 inch approx). To make a continious length of yarn from staple fiber , they must be twisted together. The length of staple fibers may be 1 cm to many.

A Staple Fiber (Soya bean fibre)

Filament Fiber:Filament fibers are of continious length (more than 5 inch). That is to say the fabrics made from filament fibers are more easier to made as the filament length are continious.

A Filament Fibre (Polyester fibres)

Some Important Characteristics of Textile Fibers:

Essential Properties:

1. Length to width ratio,
2. Strength,
3. Flexibility,
4. Cohesiveness,
5. Uniformity.

Other Properties:

1. Physical shape,
2. Specific gravity,
3. Lusture,
4. Moisture regain and content,
5. Elastic recovery,
6. Elongation,
7. Resilence,
8. Resistance to thermal behaviour,
9. Resistance to chemicals,
10. Resistance to biological agents,
11. Resistance to environmental conditions

Length to Width Ratio: Fibrous material must possess adequate staple or fiber length and the length must be considerably higher (1000 times) then the width of the fiber.

Length to Width Ratio of Some Typical Fiber Asfollows:

Fiber	Length to Width Ratio
Cotton	1400
Wool	8000
Flax	170
Silk	330000

But to be a fiber the staple length must not be less than ½ inch. According to the length, the fibers may classified into the following two categories:

1. Staple Fiber,
2. Filament Fiber.

Strength: Strength of any material is determined by the breaking strength (that is tenacity strength) which express as force per unit cross-sectional area. With this term (strength / tensile strength) we may describe the ability of a bundle of fiber of yarn to resist breakage under tension / load.
In case of describing the strength of individual fiber the term tenacity is usually used.



Tenacity: According to ASTM (American Society of Textile Manufacturers), the tensile strength when expressed as force per unit linear density is called tenacity. Tenacity is determined by applying a force to a known unit of fiber and measuring the force to break the fiber.

That is, tenacity = breaking load/ mass per unit length

Tenacity express as grams pertex(gtex) or grams per denier(gd).



Tenacity of Some Common Fiber:

Fiber	Grams Per Denier
Raw cotton	3.0 - 4.9
Jute	3.0 - 5.8
Flax	2.6 - 7.7
Ramie	5.5
Silk	2.4 - 5.1
Wool	1.1 - 1.7
Hemp	5.8 - 6.8

Flexibility: It is one of the essential property of textile fiber. The fibers should be sufficient by poliable, then only it can be wrapped around another fiber during spinning. Many substance in nature resemble fibrous forms but they are note pratical fibers as they are stiff and brittle.



Cohesiveness: It may also be termed as spinning quality of fiber. It is the property of an individual fiber by virtue of which the fibers are hold on to one another when the fibers are spun into yarns.



Uniformity: It may describe the similarities in length of fiber which are spun into yarn. To make a good quality yarn, it is important that the fibers must be similar in length and width in spinning quality and in flexibility . There is no problem in producing uniform manmade fibers but for natural fiber uniformity is difficult to achieve. So for natural fiber it is essential to blend many batches in order to manufacture good quality yarn and fabrics.



Physical Shape: The shape of fiber has good impact on the other properties of the fiber. It affects the surface irregularities and cross section of the fiber. Thus it affects the properties of the produced yarn and therefore the fabric.



Specific Gravity: The specific gravity of a fiber indicates the density relative to that of the water at 4°C. We know that the specific gravity of water at 4°C temperature is 1 per cubic centimeter or pounds per cubic foot. Density indicates the mass per unit volume and express as grams per cubic centimeter or pounds per cubic foot. Fabrics which are composed of higher specific gravity are havier than that of the fabrics produced from fibers of lower specific gravity.



Specific Gravity of Some Selected Fibers:

Fiber	Specific Gravity
Cotton	1.54 - 1.56
Flax	1.50
Jute	1.48
Silk	1.34
Wool	1.30 - 1.38
Ramie	1.51
Hemp	1.48
Glass	2.54
Asbestos	2.10 - 2.80
Viscose rayon	1.52
Nylon	1.14

Lusture: Lusture refers to gloss or shine that a fiber possess. It is actually the amount of light reflected by the fiber and it determined the fibers natural brightness and dullness. The natural fiber silk has the high lusture while another natural fiber cotton has low lusture compare to silk fiber. Man made fibers are manufactured with controlled lusture.



Moisture Regain and Moisture Content: Textile fibers generally have some contain amount of water as an internal part of their structure. This is because of the humidity present in the nature / atmosphere. Fibers with good moisture regain and moisture content will accept dyes and chemicals more readily than fibers with low regain. A few fibers have regain and thus it creats problems relative to processing. Again the relation of fiber strength to moisture content is an important consideration in the evaluation of fiber behaviour. Some fiber are stronger when wet than dry, some are weaker when wet than dry and some shows no change. Therefor, the maintainance of textile products are influenced by the strength regain relationship.



Humidity: Humidity is a term used to describe the amount of moisture present in the nature / atmosphere. These can be described in terms of absolute humidity and relative humidity.



Absolute Humidity: It is the weight of water present in an unit volume of moist air. It is the actual density of water vapour in the atmosphere and it can be expressed in terms of grams per cubic foot or grams per cubic metre.



Relative Humidity: It is the ratio between actual vapour pressure to the saturated vapour pressure and expressed as percentage.
Relative humidity = Actual vapour pressure / Saturated vapour pressure × 100
The changes in the relative humidity will change the amount of moisture in a sample of moisture regain and moisture content.



Moisture Content (M): It is defined as the weight of water in a material expressed as a percentage of the total weight of the material.

Moisture content (M) = Weight of water in the material / Total weight of the material × 100

OR

Moisture content (M) = Conditioned weight – Dry weight / Conditioned weight × 100

Conditioned weight refers to treat the material at the present condition of the atmosphere.



Moisture Regain: It is defined as the weight of water in a material expressed as as percentage to the woven-dry weight of the material.


That is,


Moisture regain (R) : Weight of water in the material / Woven dry weight of the material × 100
OR
Moisture regain (R) = Conditioned weight – Dry weight of material / Dry weight of material × 100



Woven Dry Weight: The woven dry weight is defined as the constant weight obtained by drying the material at a temperature of 105°C ± 3°C till the moisture is expelled.



Some Moisture Regain of The Common Fibres:

Fiber	Regain at 75°F and 65% Relative Humidity	Regain at 70°F and 95-100% Relative Humidity
Raw Cotton	8.5	15
Mercerize Cotton	10.3	-
Silk	11	25
Wool	16	29
Acetate	6.5	14
Viscose Rayon	11.5 - 16	27

Standard Atmospheric Condition: For testing of the textile materials, in the testing laboratory it is necessary to maintain a standard atmosphere. The advantage of conducting the test under standard atmosphere is that, the obtained result are easily comparable and can be reproduced.



Standard Atmosphere: It is defined as an atmosphere prevalling boromatric pressure where the relative humidity is 65% and the temperature is 20°C (For winter season country) and 25°C (For subtropical country).



Standard Testing Atmosphere: It is the atmosphere where the relative humidity is 65% ± 2% and the temperature is of 20°C ± 2°C (68°F ± 4°F). In the subtropical country it is difficult to obtain this temperature. So the standard temperature is 25°C±2°C.



Elastic Recovery: Elastic recovery is the percent to return from elongation towards its original length. If a fiber returns to its original length from a specified amount of attenuation, it is said to have 100% elastic recovery at x-percent elongation. Elastic recovery is expressed as percentage. The elasticity or elastic recovery of a fiber is determined by several aspects like what type of load is applied and how many times it is held in the stretched position.



Elongation: When a fiber is subjected to a force it will stretch to a certain degree. The stretching is described as the elongation or extension. It may be measured either as an elongation under certain load or an elongation reached under the fiber breaks. Elongation is expressed as percentage.



Breaking Elongation and Elastic Recovery of Some Common Fibres:

Fiber	Dry Elongation	Percentimmediat Elastic Recovery at X-Percent Elongation
Cotton	3 - 10	74 at 2%
Flax	2.7 - 3.3	65 at 2%
Hemp	1.8	-
Jute	1.7 - 1.9	74 at 2%
Silk	13 - 25	70 at 2%
Wool	20 - 40	99 at 2%

Resilency: Resilency is the ability of fiber to bounch back or return to its shape following compressions , bending or similar deformations. Resilency is important to determine the crease recovery of a fiber or fabric.



Thermal Behaviour / Properties: The behaviour of fibers on heating has real importance, particularly with in the range of temperatures , that are met in practical use. Fabric should be withstand the temperatures used in processing, drying, ironing without undue deterioration. Flammability of fiber has also great importance during its use. Generally synthetic fibers are more flammable than the natural fibers.



Resistance to Biological Agents: Some fibers basically for natural fiber, they are destroyed by the biological agents. So the fibers must be able to protect themselves from the destructive effects of the biological agents.



Resistance to Chemical: Processing of fibers, yarns and fabrics often involve the use of chemicals of great variety. Bleaching agents, Detergents, Alkalis, Acids, Dyeing and finishing assistances and other chemicals are used in preparing the finished
textiles. The fibers must be withstand these substances without suffering harmful effects.



Resistance to Environment Conditions: Many of the times the finished textiles are in contact with the environment such as sunlight, uv ray, rainfall etc. Besides these the wind in different seasons contains different elements. So the fibers used in different seasons must be preferable with the environment and have to withstand the various environment conditions with suffering much.