Fibre Properties

Properties essential to make a Fiber

Fiber Properties for specific requirements

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 

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
• 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

 

 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
Flurocarbon	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

  

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

  

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% sulhric
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