Properties essential to make a Fiber.

There are several primary properties necessary for a polymeric material to make an adequate fiber.Certain other fiber properties increase its value and desirability in its intended end-use but are not necessary properties essential to make a fiber. Such secondary properties include moisture absorption characteristics, fiber resiliency, abrasion resistance, density, luster, chemical resistance, thermal characteristics, and flammability.

• Fiber length to width ratio,
• Fiber uniformity,
• Fiber strength and flexibility,
• Fiber extensibility and elasticity, and
• Fiber cohesiveness.

Utility of fibers are broadly catagorized into 2 different uses- one is Apparel or Domestic use and the other is Industrial use.In order to be used in each of these each of these catagories the fiber has to meet some specific requirements.
They are: 

Apparel/Domestic Requirements

• Tenacity: 3 - 5 gramddenier
• Elongation at break: 10 - 35%
• Recovery from elongation: 100% at strains up to 5%
• Modulus of elasticity: 30 - 60 gramddenier
• Moisture absorbency: 2 - 5%
• Zero strength temperature (excessive creep and softening point): above 215°C
• High abrasion resistance (varies with type fabric structure)
• Dye-able
• Low flammability
• Insoluble with low swelling in water, in moderately strong acids and bases and conventional organic solvents from room temperature to 100°c
• Ease of care

Industrial Requirements

• Tenacity: 7 - 8 graddenier
• Elongation at break: 8 - 15%
• Modulus of elasticity: 80 graddenier or more conditioned, 50 graddenier wet
• Zero strength temperature: 250° C or above

Examples of Fiber Shapes

Heat helps the fiber /fabric to gain certain special qualities at certain times and are also harmful at other times.But under special guidance,heat helps fiber acquire the following characteristics

• Softening, melting, or decomposition temperatures
• Tendency of the fiber and fabric to shrink when heat-relaxed, or stretch when heated and under tension
• Ability of the fabric to heat set
• Ability of the fabric to function properly at elevated temperatures in one time or repeated use
• Ability of the fabric to function properly at room temperature (or some other lower temperature) after exposure at high temperature for a given period of time