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Properties essential to make a Fiber

Each fiber has particular properties which help us to decide which particular fiber should be used to suit a particular requirement. Certain fiber properties increase its value and desirability in its intended end-use but are not necessary 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

Examples of Fiber Shapes

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
  • 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

Fiber Melting Point Softening Sticking Point Safe Ironing Temperature
°F °C °F °C °F °C
Natural Fibers
Cotton Nonmelting 425 218
Flax Nonmelting 450 232
Silk Nonmelting 300 149
Wool Nonmelting 300 149
Manmade Fibers
Acetate 446 230 364 184 350 177
Arnel Triacetage 575 302 482 250 464 240
Acrylic 400-490 204-254 300-350 149-176
Aramid Does not melt, carbonizes above 800F
Glass 1400-3033
Modacrylic 410 210 300 149 200-250 93-121
Novoloid Nonmelting
Nylon6 414 212 340 171 300 149
Nylon66 482 250 445 229 350 177
Olefin 275 135 260 127 150 66
Polyester PET 480 249 460 238 325 163
Polyester PCDT 550 311 490 254 350 177
Rayon Nonmelting 375 191
Saran 350 177 300 149 Do not iron
Spandex 446 230 347 175 300 149
Vinyon 285 140 200 93 Do not iron

Density and Moisture Regain of Fibers

Fiber Density (g/cc) Moisture Regain
Density: Ratio of weight of a given volume of fiber to an equal volume of water.
Natural Fibers
Cotton 1.52 7-11
Flax 1.52 12
Silk 1.25 11
Wool 1.32 13-18
Man-made Fibers
Acetate 1.32 6.0
Arnel Triacrylic 3.2
Acrylic 1.17-1.18 1.3-2.5
Aramid 1.38-1.44 4.5
Fluorocarbon 2.20 0
Glass 2.49-2.73 0-0.3
Modacrylic 1.30-1.37 0.4-4.0
Nylon 1.14 4.0-4.5
Nylon Qiana 1.03 2.5
Olefin 0.91 0.01-0.1
Polyester 1.22/1.38 0.4-0.8
Rayon 1.50-1.52 15
Rayon HWM 11.5-13
Spandex 1.20-1.22 0.75-1.3

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

Fiber Effects of Sunlight
Acrylic Little or no effect
Modacrylic Highly resistant, some loss of strength and discoloration after constant exposure
Polyester Some loss of strength, no discoloration, very resistant
behind glass
Rayon Generally resistant loses strength after long exposure
Acetate Approximately same as rayon
Triacetate Resistant loses strength after long exposure
Nylon 66 No discoloration, strength loss after long exposure
Olefin Very resistant retains 95% strength after 6 months exposure
Glass None
Cotton Strength loss on long exposure
Wool Strength loss, dyeing is affected