General Properties of Textile Fiber | Physical and Thermal Properties of Fiber

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Fibers are the primary raw material of textile processing. There are many kinds of textile fibers whose general properties are similar but not exactly same to each other. Some common properties must contain by the fibers to spin into yarn. All the fibers are not textile fibers so the basic properties are very important to be a textile fiber. 

General properties of Textile Fibers are of three categories:

• Physical Properties
• Chemical Properties
• Thermal Properties

Physical Properties:

Length to width ratio:  For the processing of fibers into yarns and then fabrics length must bigger than width. The minimum length to breadth ratio is 100:1.  Length of fibers is also classified into two groups as staple and filament. Staple fibers are of relatively short length fibers; and filament fibers are long length fibers. 

Fiber Fineness: This is the properties of fiber coarseness. Fineness of a natural fiber is a major factor in ascertaining quality and is measured in microns(1 microns= 1/1000millimeter). In general, finer fibers are softer, more pliable and have better drape ability. It is expressed with micronaire value and measured in denier. In case of synthetic fibers, fineness is controlled by the size of holes of the spinneret.

Tenacity (Strength): Strength of textile fibers is referred to as their tenacity. It is determined by measuring the force required to rupture or break the fiber. Sufficient tenacity is required to withstand the mechanical and chemical processing as well as make textile products which are durable. Tenacity is directly related to the length of the polymers, degree of polymerization, strength in dry and wet conditions, and types of inter- polymer forces of attraction formed between the polymers.

Flexibility:  Fibers should be flexible or pliable in order to be made into yarns and thereafter into fabrics that permit freedom of movement. Certain end uses require greater flexibility, e.g., automobile seat belts. 

Uniformity:  Uniformity of fibers towards its length, ensure production of even yarns which can then form fabrics of uniform appearance and consistent performance.  

Cohesiveness or spinning quality: It is the ability of the fiber to stick together properly during yarn manufacturing processes. Natural fibers have inherent irregularities in their longitudinal or cross sections which permit them to adhere to each other during fiber arranging. In case of synthetics, filament lengths aid in yarn formation. Texturing introduces coils, crimps, curls or loops in the structure of an otherwise smooth filament.

Morphology:  It is the study of physical shape and form of a fiber. It includes microscopic structure like longitudinal and cross sections. These also include fiber length, fineness, crimp, color and luster. 

Physical shape: Shape of a fiber include, its longitudinal sections, cross section, surface contour, irregularities and average length.

Luster: It refers to the sheen or gloss that a fiber possesses. It is directly proportional to the amount of light reflected by a fiber. This in turn is affected by their cross section shape. It is seen when light reflected from a surface. It is more subdued than shine. Silk and synthetics have luster than cellulosic fibers. In fact synthetics have high luster which is purposefully removed during spinning.

Crimp: Wool fiber is more or less wavy and has twists. This waviness is termed as crimp. Finer the wool more will be the crimps in it. Marino wool will have 30 crimps per inch while coarse wool has only one or two. This property of havingcrimps gives elasticity to the fiber..

Elongation and Elasticity: The amount of extension or stretch that a fiber accepts is referred to as elongation. Elongation at break is the amount of stretch a fiber can take before it breaks. Elasticity is the ability of stretched material to return immediately to its original size.

Resiliency: It refers to the ability of a fiber to come back to its original position after being creased or folded. Resilient fibers recover quickly from wrinkling or creasing. Good elastic recovery usually indicates good resiliency. This property is described qualitatively and ranges from excellent to poor. Excellent resiliency is exhibited by polyester, wool and nylon fibers. Flax, rayon and cotton, on the other hand, have a low resiliency.

Moisture regain: The ability of a dry fiber to absorb moisture from atmosphere is generally termed as moisture regain. Measurements are done under standard testing conditions (70°± 2F and 65% ±2% relative humidity). 

Chemical Properties:

Water Absorbency: Fibers are of two categories inherently as hydrophobic or hydrophilic. Hydrophobic fibers have no affinity towards water and hydrophilic fibers are of opposite character. Natural fibers are good in terms of absorbency than any kind of synthetics.

Resistance Power to Acid:  Cellulosic fibers are not resistant to Acid solution whereas synthetics have good resistance power.

Resistance Power to Alkali: Cellulosic fibers have fairly resistance power to alkali, especially in mild alkaline medium it does not get harmed but in strong alkaline medium fibers become affected. Synthetics have good resistance power in both mild and strong alkali.

Thermal Properties:

 Flammability: Burning characteristics of fiber groups vary from each other and can, thus be used as an authentic identification method. Reaction to flame can be further broken down into; behavior when approaching flame, when in flame and after being removed from flame.

Electrical conductivity(Static Electricity):  It is the ability of a fiber to transfer or carry electrical charges. Poor or low conductivity results in building up of static charges. This leads to the clinging of clothing and in extreme cases can produce electrical shocks, which produce crackling sound or even a tiny spark. Acrylic is a poor conductor of electricity.  Water is an excellent conductor of electricity and fibers with high moisture regains will never face the problem of static build-up.

Abrasion: The wearing away of a material by rubbing against another surface is called abrasion. 

Other thermal characteristics of fibers are important in their use and care like washing, drying and ironing are selected on the basis of a fiber’s ability to withstand heat.