Properties essential to make a Fiber

Fiber Properties for specific requirements

The utility of fibers are broadly categorized 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 categories, the fiber has to meet some specific requirements. They are:

Apparel/Domestic Requirements

• Tenacity: 3 – 5-gram denier
• Elongation at break: 10 – 35%
• Recovery from elongation: 100% at strains up to 5%
• Modulus of elasticity: 30 – 60-gram denier
• 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 at room temperature
  to 100°c
• Ease of care

Industrial Requirements

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

Basic Textile Fiber Properties

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.

Some Primary Properties of Textile Fibers are:

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

How heat affects Textile Fiber’s properties

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
• The tendency of the fiber and fabric to shrink when heat-relaxed, or stretch when heated and under tension
• The ability of the fabric to heat set
• The ability of the fabric to function properly at elevated temperatures at one time or repeated use
• The 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

Thermal Properties of Common Fibers

Density and Moisture Regain of Fibers

The chemical composition of some common fibers

Type of fiber	Cellulose	Lignin	Pentosan	Ash
Seed flax	43-47	21-23	24-26	5
Kenaf (Bast)	44-57	15-19	22-23	2-5
Jute (Bast)	45-63	21-26	18-21	0.5-2
Hemp	57-77	9-13	14-17	0.8
Ramie	87-91	–	5-8	–
Kenaf (Core)	37-49	15-21	18-24	0.8
Jute (Core)	41-48	21-24	18-22	–
Abaca	56-63	7-9	15-17	1-3
Sisal	43-62	7-9	21-24	0.6-1
Cotton	85-96	0.7-1.6	1-3	0.8-2

The diameter of Natural and Meltblown Fibers

Material	Diameter Mean Value (microns)	Coeff Variation(%)
Spider silk	3.57	14.8
B. mori Silk	12.90	24.8
Merino Wool	25.50	25.6
Polyester	13.30	2.4
Nylon 6 Filament	16.20	3.1
Kevlar 29	13.80	6.1

Effects of Acids on Common Fibers – Comparison

Fiber	Effects of Acids
Acrylic	Resistant to most acids
Modacrylic	Resistant to most acids
Polyester	Resistant to most mineral acids disintegrated by 96% sulphuric
Rayon	Disintegrates in hot dilute and cold concentrated acids
Acetate	Soluble in acetic acid, decomposed by strong acids
Triacetate	Similar to acetate
Nylon 66	Decomposed by strong mineral acids, resistant to weak acids
Olefin	Very resistant
Glass	Resists most acids. Etched by hydrofluoric acid and hot phosphoric acid
Cotton	Similar to rayon
Wool	Destroyed by hot sulfuric, otherwise unaffected by acids

Effects of Alkalies on Common Fibers – Comparison

Fiber	Effects of Alkalies
Acrylic	Destroyed by strong alkalies at a boil, resists weak alkalies
Modacrylic	Resistant to alkalies
Polyester	Resistant to cold alkalies, slowly decomposed at a boil by strong alkalies
Rayon	No effect by cold, weak alkalies, swells and loses strength in concentrated alkalies
Acetate	Saponified, little effect from cold weak alkalies
Triacetate	Not effected up to pH 9.8,205′ F; better than acetate
Nylon 66	Little or no effect
Olefin	Very resistant
Glass	Attacked by hot weak alkalies and concentrated alkalies
Cotton	Swells when treated with caustic soda but is not damaged
Wool	Attacked by weak alkalies, destroyed by strong alkalies

Effects of Organic Solvents on Common Fibers – Comparison

Fiber	Effects of Organic Solvents
Acrylic	Unaffected
Modacrylic	Soluble in warm acetone, otherwise unaffected
Polyester	Soluble in some phenolic compounds, otherwise unaffected
Rayon	Unaffected
Acetate	Soluble in acetone, dissolved or swollen by many others
Triacetate	Soluble in acetone, chloroform and swollen by others
Nylon 66	Generally unaffected, soluble in some phenolic compounds
Olefin	Soluble in chlorinated hydrocarbons above 160′
Glass	Unaffected
Cotton	Resistant
Wool	Generally resistant

Effects of Sunlight on Common Fibers – Comparison