Classification of Textile Fibers
Textile fibers are broadly classified into two major groups: (1) natural and (2) man made, depending upon the nature of their origin. Natural fibers still account for a major share (some 45%) of the total textile fiber consumption around the world. The term ''man made'' applies to all fibers that include those regenerated from natural products as well as those that are synthesized from basic chemicals. There are a variety of texts dealing with the general classification, properties and chemical compositions of textile fibers and the synthesis
of manmade fibers . In recent years, the original list of manmade fibers has been supplemented by a variety of newly synthesized fibers, engineered specifically for high performance end uses, such as aramid, polysulfide, and polybenzimidazole to name a few. Natural fibers are further subdivided into (a) animal, (b) vegetable, and (c) mineral. The fibers from animal sources can be further subdivided into silk, wool, mohair, cashmere, and hair. Vegetable fibers are subdivided into (i) seed fibers (e.g., cotton); (ii) bast fibers (e.g., flax, hemp, jute, and ramie); (iii) leaf fibers (e.g., manila, sisal, and abaca); and (iv) fruit fibers (e.g., coir). Manmade fibers are divided into two main categories,
A. Natural polymer fibers in which the fiber-forming polymer is of natural origin, referred to as regenerated fibers.
B. Synthetic fibers in which the fiber-forming material(s) is from basic chemicals. There is now also a new class of synthetic fibers, those produced from material derived from a natural renewable origin, such as corn, known as polylactic acid or polylactide (PLA).
Regenerated fibers derived from natural polymers are further subdivided into four groups, namely:
A. Cellulose fibers (e.g., viscose, polynosic, cuprammonium rayons, and Tencel or lyocell)
B. Protein fibers (e.g., casein)
C. Cellulose esters (e.g., acetate and triacetate)
D. Miscellaneous fibers (e.g., alginate and natural rubbers)
It is more convenient to classify synthetic fibers according to their chemical structure. They fall into the following ten subdivisions:
A. Polyurethanes (e.g., Spandex_)
B. Polyamide (e.g., nylon 6, nylon 6.6, etc.)
C. Polyesters (e.g., Dacron_)
D. Polyvinyl derivatives:
i. polytetrafluoroethylene (PTFE)
ii. Polyvinylchloride (PVC)
iii. Polyvinylidene chloride
iv. Polyacrylonitrile (PAN)
v. polyvinylidene dinitrile
vi. Polyvinyl alcohol (PVA)
vii. Polystyrene
viii. Miscellaneous polyvinyl derivatives
E.Polyolefins (e.g., polyethylene and polypropylene)
F.Polysulfide (e.g., PPS)
G.Aramids (e.g., Kevlar_ and Nomex_)
H.Novoloid (e.g., Kynol_)
I. Miscellaneous (e.g., glass, metallic, carbon, and ceramics)
J.Polylactic acid or polylactide (PLA)
Fibre
Definition: Fibre is pliable hair like substance that is very small in diameter in relation to their length. They are the fundamental units used in making of textile yarn and fabrics. Certain quality are desirable to say a fibre as textile fibre, first to be a fibre at all, the length must be several hundred times the width. It is this that enables fibres to be twisted together to form a yarn or thread.
There are two types of textile fibre:
Natural
fibre:
Wool, silk, specially hair fibres, cotton, flax, jute, hemp, pineapple, abaca,
sisal, kapol, asbestos.
Man-made
fibre:
Rayon, acetate, nylon, acrylic, modacrylic, polyester olefin, spandex, saran,
glass, vival vinyon, azlon, metallic, lastrile, nytrile.
# General properties of textile fibers:
A) Physical properties:
1. Length: It depends upon the types of fibres. It is fine in case of m.m.f but varies largely in case of natural fibres .i.e. average length of cotton is 2”. The lengths are measured in three ways:
I. Average length - By number or weight of fibre.
II. Effective length - Which is the average length of the longer fibre of the bundle.
III. Staple length - Fibre length as assumed by expert person.
a) Short length - 2”
b) Medium length - 2-4”
c) Long length - > 4”
#The effect of length:
I. Strength - The longer fibres are weaker than the shorter ones but they can give stronger yarn due to friction. (High cohesive forces).
II. Processing - Cotton, Jute, Wool, etc. need individual machine for spinning due to its length.
III. Appearance – Long fibres are smoother than shorter fibres yarn made up of long fibres have less fibres projection while the yarn made up of shorter fibre have more projection.
2. Strength and extension: The capability of a fibre to support a load is known as its strength. In case of fibre, the strength is described as tenacity. i.e
Tenacity = strength/linear density.
Tenacity is expressed in terms of CNN/Tex or N/Tex.
The tensile strength (breaking load) is commonly described as the force required to reach break, the increase in the length before breaking is known as extension.
3. Flexibility: Flexibility is that property to resist repeated bending and folding.
4. Cohesiveness: Is the ability of the fibres to cling together during spinning depends on crimp and twist (natural).
5. Uniformity: To make yarn it is important that fibres be similar in length and width, in spinning quality and in flexibility.
6. Fineness: The term fineness describes the quality of a fibre. By this, we can know how fine a fibre is. It is express by the terms count, tex, denier. Tex is weight per unit length. 1 tex = 1 gm / 1000 M. 1 Denier = Wt in gram / 9000 M. England system, Hair weight = gm X 10-8 /Cm2.American system, Micronair value = gm X 10-6 / Inch. Mill tex = Wt in m gm / 1000 M. Deci tex = wt in gm / 10000M.
Effect of fineness:
i. Yarn count: No of fibre increase or decrease in cross-section of a yarn depending upon fibre fineness. Finer fibres produce finer yarn.
ii. Yarn strength: Finer fibres give stronger yarn and vice – versa as finer fibre contain more fibre.
iii. Yarn regularity: Finer fibre give more regular than coarser fibre.
iv. Fine fibre gives less weight fabric.
v. It gives a large total surface area which is essential for thermal insulation.
vi. It absorbs and deserves more water vapour from the atmosphere than coarser fibres.
7. Cross-section: The cross-section of a fibre determines the physical properties of the fibre. It gives idea about strength fineness which varies from fibre to fibre.
8. Crimp: It refers to the weaves or bends that take palace along the length of a fibre. It increase the cohesiveness & resilience, resistance to abortion (i.e Rubbing, scraping) and gives increased bulk or warmth to fabrics. It also helps fabric to maintain their softness or thickness, increase absorbility and show contact comforts by reduce lusture. A fibre may have one of the three types of crimp namely mechanical crimp, natural crimp, inherent crimp & chemical crimp.
9. Elasticity: It is the power of recovery from deformation. The fibre may be plastic or elastic which depends upon fibre condition and surrounding environment.
10. Resiliency: It is the property of a fibre which enables it to recovery from a certain load or stretch over a period of time.
11. Toughness: The ability of a fibre to endure large permanent deformation without rupture is called toughness.
12. Work of rupture: The area below the stress strain curve provides a measure of the work required to break the fibre, it is called work of rupture and is commonly express in CN/Tex.
13. Appearance: It is express by length, fineness, cross-section, cleanness and luster of a fabric. Generally short fibres are bulkly and less lusturous.
14. Density: The density indicates the mass per unit volume. The specific gravity of a fibre indicates the density relative to that of water at 4OC.
#Chemical Properties:
1. Water: Water is very important to determine the properties of fibres. According to behavior of fibres with water, fibres are classified into two groups: Hydrophobic & Hydrophilic. We need different process for different fibres. The dyes which are suitable for cotton, wool and silk (hydrophobic) are not fit for terylene, orlon(hydrophobic). Water is used in process like scouring, Dyeing. Absorbency: Is the ability of fibre to take up moisture and is express in terms of moisture regain. Depends on the polarity of the polymers and the ratio of its amorphous and crystalline region.
Attracting groups -OH, -NH, -CONH
Non attracting groups -CH, -COO, -CH3
Semi attracting groups -Cl, -OCOCH3, -CN
2. Acid: Textile fibres and materials are subjected to acid in various processing like bleaching. The different kinds of fibres react differently with acids. The acids must choose properly to use different process. So that it doesn’t make any harm to the fibre but brings the required change perfectly.
3. Alkali: Different kinds of fibres behave differently with different alkalis in different situations. For example, caustic soda in dilute solution & low temperature dissolves the wool fibres. Whereas the mild alkalis have no injurious effect on wool at ordinary concentration. It is used to many processes as dyeing, sizing and finishing.
4. Heat: Textile fibres are subjected to heat in dyeing, drying, steaming, decanting, calendaring, boundening, pressuring and issuing operation. Some fibres become tough under heat such as rayon, resin, where as some bum under heat such as flax, cotton, jute etc.
5. Sunlight: Sun light reacts different fibres and fabrics. For example, White fabrics become increasingly yellow with increased exposure and the dyed fabrics become faded in various degree. Again, black absorbs more sun’s heat than the white one.
6. Moisture (MR% & MC %): Fabrics are comfortable or not due to their behavior towards moisture. Moisture regain is measured in ideal weather which effect on the comfort strength and winding process of a fibre. Moisture regain is the amount of moisture present in textile material expressed as percentage of the oven dry weight of the textile. The dry mass is the constant weight of textile obtained after drying at a temperature of 105 to 110OC
MR%= (A-B)/Bx100
Where, A=Conditional weight at (20OC & 65O R.H) B= Oven dry weight
M/C%= Is the amount of moisture present in a textile material expressed as percentage of the condition weight of the textile.
MC %=( A-B) X100
8. Biological agent: If fibres are attacked by bacteria, black spots are seen on the fibres as a result of which the strength of fibre is reduced. It is important weather fibres attached by micro organism or not, upon which strength of products depends.
The Cellulose Fiber
The Cellulose Fiber: Natural Cellulose fibers: Cotton, Flax, Jute, Hemp etc. Man-made cellulose fibers: Rayon etc.
Cellulose, the basic unit of cellulose.
#Properties common to all cellulose fiber:
|
Property |
Importance to consumer |
|
1. High Density (1.5+) |
Fabrics feel heavier. |
|
2. Good Absorbency |
Comfortable for summer wear |
|
3. Good conductor of Heat |
Sheer fabrics and for summer wear |
|
4. Can withstand high temperature |
Fabric can be boiled. No precaution for ironing. |
|
5. Low resiliency |
Fabrics wrinkle badly until finished for recovery. |
|
6. Lacks loft, packs well into compact yarns |
Yarn can be creped. High count fabrics can be made |
|
7. Good conductor of electricity |
Does not built up static |
|
8. Harmed by mineral acids but little affected by organic |
Fruit stains should be removed immediately from a garment. |
|
9. Resistance to moth 10. Attack by mildew |
No storage Problem. Solid garments should be put away damp. |
|
11. Flammability |
Cellulose fibers ignite quickly, burn freely, have an after glow and grey feathery ash. |
|
12. Resistance to sunlight |
Draperies should be lined. |
Cotton Fibre
#Feature: Low cost, Low resiliency, Launder ability, Absorbent.
#Classification: Natural cellulose, seed monocular staple fibre.
#Producing country: USA, India, China, Russia, Egypt and Brazil.
#Commercial verities of cotton: The more important varities in order of decreasing fibre length.
1. Sea Island cotton: The fibre length may be up to 2 3/8 but average is 1 4/3 in west indies. The American sea island ranges from 1 5/16 to 1 13/16 mostly between 1 ½ to 1 10/16 production of this variety is small per acre than other varity. Fineness 1.2 to 1.8 dtex.
2. Egyptian cotton: Cotton ranges length 1 ½ to 1 5/8.
3. Upland cotton: Ranges from ¾ to 1 3/8. Average upland cotton is above 1” the cis upland cotton ranges from 1/8 to 1 3/32
4. Indian variety: The average staple length ranges from 1/8 to 1”. Two third of Indian cotton estimated staple length 3/8 to 7/8.
5. China cotton: This is short fibre of 6 to 8 inch length.
#Botanic Name: Cotton is the hair of shrub plant which bears the botanic name Gossypium, a member of the Mallow family, Cultivated as an annul plant.There are 50 species of cotton plants however only four of them have attained commercial importance.
#Chemical composition:
Cellulose = 85.5%
Oil and wax = 0.5%
Proteins, pectoses and coloring matter = 5%
Mineral matter = 1%
Moisture = 8.5%
#Polymer system: Cotton is crystalline fibre. Its polymer system is about 65 to 70 percent crystalline and correspondingly, about 35-30 % amorphous. DP - 2000+.
#Physical structure:
#The micro structure: The cotton fibre is made up of a cuticle, primary wall, secondary wall and lumen.
The macro structure of cotton:
Length = 1 cm to 6.5 cm
Diameter =11 µm to 22 µm
Convolutions = Sixty per centimeter
Color = generally white, may be creamy or brown.
Length width ratio = 6000:1 to 350:1
Length reflection = Low luster,dull appearance.
#Physical properties:
1. Specific gravity = 1.52 to 1.55
2. Strength tenacity = dry 3.5 g/d ; Wet = dry X 1.11
3. Elasticity Low, Breaking extension 5-7% & Recovery(%) 52 at 5%
4. Stiffness – 57-60 g/d ( dye to high crystalline )
5. Resiliency low
6. Absorbency low
7. Abrasion resistance medium
8. Dimensional stability medium
#Chemical properties:
1. Acid - weaken and destroyed hydrolyze the glucoside oxygen atom, concentrate nitric acid, for short time, cause some shrinkage and increase strength and dye ability.
2. Alkali- normally resistance, when boiled in presence of O2, oxycellose form treating with 20% NAOH increase strength and dye ability, process is called Mercerization, Liquid ammoria treatment increase strength, elongation etc.
3. Bleach all kinds; NaOCl and Na-perborate are common. H2O2 is last harmful.
4. Organic solvent-resistance. So dry wash is possible
5. Heat-Conductive ironing temperature 1500C , Decompose 2400C, Ignition temp 3900C
6. Sun light-affected by infrared cause deteriorates color becomes yellow.
7. Dye ability -Azoic, Direct, Reactive, Sulpher and vat dye
8. Attack by moth-No (Attack by silver fish)
9. Attack by mildew- Unthreaded not easily but starches and gum increase activity.
#Applications:
Cotton is used to make fabrics that are universally used for all types of:
· Apparel
· Home Furnishings
· Industrial Applications
FLAX Fibre
(Linen Fibre)
(High strength, low resiliency, Natural body). Classification-natural, cellulose base, multicellular fibre. Botanical-order-Linaceae
#Producing country - Russia, Belgium, Holland, England and Ireland.
#Major Producers: Western Europe is the major producer of finest quality linen; China is also one of the leading producers of high quality linen. Ireland, Italy and Belgium are other significant producers. Belgium produces the best quality linen, and Ireland is known for its craftsmanship. Linen is a bast fibre obtained from the stem of the flax plant. Which grows in region of the abundant rainfall. Linen is one of the oldest and a very popularly used fibre obtained from the stalk of the flax plant. The hair like fibres, are held together by a gummy substance known as pectin. Linen is composed of 70 percent cellulose, and 30 percent pectin, woody tissue, ash and moisture. Linen is popularly used as a generic term to describe bed, bath, table and kitchen textiles and furnishings as it was traditionally used for towels, sheets, etc. It is one of the most prestigious and expensive fibre, grown in small quantities, in various parts of the world.
#Molecular structure:
#Chemical composition
Cellulose 63%
Fat 1.08%
Pectin bodies 1.69%
Water 11.61%
Gum + Wax 21.00%
Ash 0.63%
#Macro structure: Consist of bundle of individual fibre held together by natural cements. The fibres are composed of single cell about 3 to 6 cells that is 25mm long 16-20µm thick. The surface of the fibre is smooth, with protuberances called nodes irregularly spaced along the length. A cross-section view reveals that the individual fibres are polygonal in shape with a thick fleshy wall surrounding a centra hollow core or lumen. These are no convolutions as in cotton but longitudinal lines or striations may be seen.
#Physical Characteristics: The fibre is smooth, straight and lustrous. It is more brittle and less flexible than cotton. The fibre is also more difficult to spin into yarn. It has a long staple fibre length when compared to cotton.
#Physical properties:
1. Specific gravity -1.50
2. Moisture regain -12
3. Strength tenacity; Dry = 6.6 & Wet = dry X1.11 . Due to high crystalline, more hydrogen bond.
4. Elasticity - (Lowest among natural fibre)
Breaking extension – 3%
Recovery (%) 65 at 2%
5. Specific heat - 0.322
6. Resiliency - low, Abrasion resistance moderate, dimensional stability good.
#Chemical properties:
1. Effect of acid/alkali- Same as cotton, but has good resistance to alkali. Flax contains a certain Wax like substance (0.5-2%) which may be extracted with benzene or ether.
2. Heat- Better conductor of heat so cooler to touch. Attack by fungi and moulds-yes. Attack by insects-no
3. Dye ability - Not a good. Direct and vat is suitable.
4. Sunlight- Become weak as cotton.
5. Effect of bleaches- Unaffected by common household uses.
6. Organic solvents- Resistance to organic solvents.
7. Resistant to stains- Good.
8. Dye ability- No good affinity, direct, vat dye are used.
9. Conductivity- Good electrical and heat conductivity.
#Applications: Linen is one of the widely used fibre used in:
· Apparels · Home furnishings · Commercial furnishing · Upholstery
· Industrial application
Wool Fibre
#Feature: Warmth, resiliency, felting damage by moth, alkali
#Classification: Natural polymer , Multicellulor , staple fibre .
#Producing country: Australia, Russia, Newz land, Argentina, South America, Uruguay, Chin, Uk.
#Molecular structure:
#Chemical composition:
Keratin 33%
Dust 26%
Suit 28%
Fat 12%
Mineral matter 1%
#Physical properties:
1. Specific gravity 1.31
2. Moisture M.R-13-16%Very absorbent, decrease strength when wet, seem warmth, will shrink in washing.
3. Strength Tenacity dry = 1.35 g/d; wet = dry x 69
4. Elasticity Breaking extension – 42.5%
Recovery (%) -69 at 5 %
5. Feel or Hand Soft
6. Resiliency Excellent (Due to crimp)
7. Abrasion resistance Good, Dimensional stability bad (for tendency of felting)
#Chemical properties:
Effect of
1. Acid: Fairly stable, acid hydrolyses the peptide bond so weakened in acid. Concentrated HNO2 & H2SO4 destroy the fibre.
2. Alkali: Destroy all bonds and dissolves because it contains cystin.
3. Bleach: Reducing is suitable NaOCL is harmful.
4. Heat: Poor conductivity scorches easily. Smoulder rather than burn. Ironing temp- 140C, decomposed- 2040C.
5. Sunlight: Tends to yellow white or dull color or surface polymer degraded by ultraviolet radiation.
6. Dye ability: Easy to dye, acid, mordant, premetalized, reative dyestuff is suitable. Attack by moth- Carpet beetles and larve. Attack by mildew-yes.
The non- thermoplastic man-made fibres
Rayon Fibre
(Low cost, versatile, low resiliency)
# Rayon is a manufactured fibre composed of regenerated cellulose, as well as a manufactures fibre composed of regenerated cellulose in which substituents have replaced not more than 15% of the hydrogen of the hydroxyl groups.
Factors which affect the quality of the viscose rayon are:
1. Temperature & composition of the bath.
2. Speed of coagulation.
3. Length of immersion.
4. Speed of spinning.
5. Stretch imparted between the godet’s.
#Polymer system: It is a linear cellulose polymer, similar to that of cotton. The viscose polymer is very amorphous, being about 40% crystalline.
#The macro structure of viscose: Viscose is a fine regular filament or staple fibre. Diameter- 12µm to 22 µm. Have longitudinal striations (tiny grooves). Functional group: -OH
#Physical properties: Polymer system of viscose is very amorphous, its filament or staple fibre are weaker than cotton and have only a fair lenacity. Water enter into the amorphous region and break the H-bond,resulting in the weaker fibre when wet. The polymer system of the filaments will be disarranged with stress and viscose textile material will become distorted, stretched, winkle and creased.
Property Regular Polynosic Cupr
1. Specific gravity 1.5 1.52 1.54
2. Moisture regain 13 11 11
3. Tenacity 1.6-2.5 3.2-5 1.8-2.9
4. Breaking-dry 15-30 19-20 12-18
Extension wet 20-40 14-26 18-35
5. Recovery at 4% 30-75 70-100 45
6. Stiffness (g/d) 11.2 28-75 15.5
7. Softening temp. Soften at 149-1630C
8. Melting temp. Do not decompose at 176 to 2040 C.
9. Flammability Flammable
10. Resiliency Low, abrasion, resistance low, Dimensional stability-for HWM is high.
#Chemical Properties:
Effect of-
1. Acid and alkali: easily damaged by strong acids,Hot dilute mineral acids will disintegrate fibres. Concentrated alkali will cause swelling and reduced strength.
2. Bleaches: Can withstand both oxidizing and reducing bleaches. Attacked by strong oxidizing bleaches.
3. Organic Solvents: Good resistance to organic solvent.
4. Sunlight and hit: Will undergo deterioration when expose to ultraviolet light, loose strength.
5. Resistance to stain: Poor resistance to water borne stains.
6. Dye ability: Better affinity for dyes than cotton direct, vat and sulfur.
7. Micro-organism: Will resist if dry and clean.
8. Flammability: Burns rapidly.
9. Conductivity: Good conductor of heat.
#Viscose modification:
Solution dyes Cross dye able.
De-luster Ceramic
High tenacity Bacteriostatic
Carpet fibre Self-crimping
High-wet Bi-component
Modulus Tire cord
Multi-cellular Acetylated
Cross-linked
#Major difference between Rayon and Acetate:
Rayon Acetate
Cellulose Cellulose
Physically Changed Chemically & physically changed
Scorches with too much heat Mils with too much heat
Does not dissolve in aceton Dissolve in aceton
High absorbency Fair absorbency
No static Static
Wrinkle unless resin treated cotton like Resilient when dry, silk dry
#Properties of common to most thermoplastic fibre
1. Good strength and abrasion resistance, resistance to pulling and rubbing
2. Wet strength is equal to dry strength.
3. Resiliency, elasticity and elongation are good, resistance to wrinkle.
4. Low moisture absorption-advantage is a) spot resistance b) washable c) Quick drying. Disadvantage-difficult to dye, build static electricity
5. Heat sensitive-glazes or melts with hot iron.
6. Heat-setting-advantages
7. Embossed design and novelty fabrics
8. Crush- resistant pile
9. Durable plates and shape
10. Stabilized size
11. Knits do not need to be blocked. Disadvantage- “set” creases are hard to remove in pressing or altering garments.
12. High resistance to moths, mildew, insects, moulds etc. Simplifies storage problems, little loss from these causes.
Acetate Fibre
(Artificial silk Fibre)
(Cellulose ester fibres)
Cellulose with at least 92% (for triacetate), 72% (for diacetate) by weight of acctylated hydroxyl groups. Acetate is a manufactured fibre in which the fibre forming substance is cellulose acetate. Where not less than 92% of the hydroxyl groups are acetylated the term triacetate may also be used a a geeric description of the fibre.
1. Di-acetate: Secondary cellulose acetate.
2. Tri-acetate: Primary cellulose acetate.
3. Fortisan: Saponified cellulose acetate.
4. Alon: Acetylated strong viscose staple (intermediate between di and tri acetate)
#Molecular structure: Acetate is a polymer composed of units of cellulose acetate in which approximately an average or 2 of 2.5 of the three OH units per glucose residue have been replaced by OOCCH3 acetyl redicals. The degree of polymerization of acetate is between 350 to 400. Triacetate differ from acetate only in that over 92 % of the hydroxyl radicals have been replaced by acetyl group. The degree of polymerization is similar for both secondary acetate and triacetate.
#Polymer structure: Diacetate 40% crystalline triacetate more than this. Linear polymer diacetate 160 nm long, 2.3 nm thick and triacetate 240 nm long and 2.6 nm thick. Functional group: -Oh, -OCOCH3
#Physical properties:
Name: Di Tri Fortisan Alon
Specific gravity 1.32 1.3 1.5 1.34
Moisture regain 6.5 3.2 10-11 9.6
Tenacity-dry 1.5 1.4 7 2.8
(g/d) wet 0.9 0.8 6 2.2
Breaking exten 30 28 6 25
Knot strength g/d 0.9 1 2.2 1.8
Recovery (%) at 4% 65 75 70 70
Softening temp 0C 204 240 do not melt 130
Melting temp 0C 260 300 204 144
#Chemical properties:
1. Light: Long exposure leads to strength loss in each case the unsaponified fibres show slightly greater resistance than the purely cellulosic.
2. Acids: Concentrated acids, both organic and inorganic weaken the fibres and in most instances cause complete fibre disintegration. Hot acid, both dilute and concentrated, may causes decomposition or at minimum loss of strength, cold dilute acids weaken the fibre it exposure is prolonged.
3. Alkali: The secondary acetate losses its acetyl groups with worm dilute alkali, the triacetate being little affected until the boil is reached. Saponified acetate resists dilute alkali but is swollen by concentrated.
4. Organic solvents: Secondary acetate is soluble in acetone and is swollen or dissolved by several others, including alcohol, particularly when warm. Triacetate is soluble in acetone, methylene chloride and chloroform and is swollen by trichloroethylene. Organic solvents have no affect on saponified acetate.
5. Bleaches: Resistant to weak oxidizing and reducing bleaches.
6. Conductivity: Poor heat conductivity.
7. Biological: Owing to the acetyl groups, micro-organisms do not attack secondary and tertiary acetates as easily as the partly cellulosic fore e.g Saponified cellulose acetate. None of the three serves as food for insect larvae.
8. Electrical: The insulating power of the acetylated fibres is high and they are prone to acquire static charges. The effect increase with triacetate. The electrical properties of saponi fied acetate are the same as those exhibited by viscose and cotton.
#Use: Regular acetate is preferred by many designers for its outstanding drapability and desirable hand. It can be made into fabrics of varying weight, thickness and degree of softness or stiffness. Due to the thermoplastic property, it should either be dry cleaned or laundered and ironed at warm, not hot, temperatures.
Acrylic Fibre
(Poly-acrylonitrile fibre)
At least 85% by weight of acrylonitrile.
 |
Acrylic, M= at least 85% & P=15%
X=anionic radical eg –fl, -OOCH3, -CONH2
#Commercial fibre: Acrilan, Creslan, Zafran, Orlon, Courtelle
#Polymer system: Acrilan, Orlan and creslan are co-polymer. Zefran is a graft polymer. The acrylic polymer is one of the largest man-made fibre polymers. It is a linear polymer with a degree of about 2000. The makes it about 500nm long with thickness ranging from 0.3 to 0.53 nm. Functional group: SO3H2, COOH2, OSO3H.
#The macro structure of acrylic: The acrylic fibre appear as regular translucent, slightly wavy filament or staple fibre. Diameter- 15µm to 25 µm. Length width ratio: 2000:1. Color: Dull
#Physical properties: A bulky fibres, soft and warm o the touch. Recovery (%) 81 at 5% extension. Sticking 249 222 249 do not melt. Resiliency, abrasion resistance and dimensional stability is good.
#Chemical properties:
1. Effect of acid: Damaged only by strong concentrated acids good resistance to mineral acids used in spot and stain removal.
2. Resistance to stains: Good for water borne, poor to fair for oil-borne stains.
3. Flammability: Burns rapidly with bright, yellow flame, produces not residue.
4. Conductivity: Fair for electrical, medium for heat.
5. Bleaches: Resistance.
6. Organic solvent: Resistance to all.
7. Alkali: Resistance to weak but affected by boiling strong detergent, washing soda eventually lead to discoloration, yellowing.
8. Light: Resistance.
9. Heat: Most heat sensitive tends to ignite immediately rather than melt and then burn as do nylon and polyester fibre. Do not heat set.
10. Dye: acid, basic, premetalized, cationic.
#Modacrylic: Less than 85% but more than 35% by weight of acrylonitrile. Dynel- 60% vinyl chloride and 40% acrylonitrile. Verel- Vinylidene chloride and acrylonitrile.
#Physical properties of modacrylic:
Name Dynel Verel
1. Specific gravity 1.30 1.37
2. Moisture regain 0.4 4
3. Tenacity (g/d) 3.3 2.8
4. Breaking extension 35% 32%
5. Stiffness (g/d) 8.2 8
6. Sticking tempoC 149 149
7. Flammability Will not support combustion
#Chemical properties:
1. Effect of Acid & Alkali- Excellent resistant moth and mildew. Resistance, if food is furnished on the surface damage will reslt.
2. Dye- Dynel-disperse, acid, direct, cationic, premetalized, Vat.Verel-disperse and basic.
Nylon Fiber
(Polyamide fibre)
#Nylon is manufactured fibre in which the fibre forming substance in any long chain, synthetic polyamide having recurring amide groups (-CO-NH-) as an integral part of the molecular chain.
#Polymer system: Linear, but nylon 6.6 have zigzag arrangement. Nylon 6 polymer is 90 nm long and 0.3nm thick, nylon 6.6 is 92 to 140 nm long and 0.3 nm thick. 65-85% crystalline.
#Functional group: Polar amide group –NH2,-COOH
#Appearance: Smooth, glassy rods of almost circular cross-section.
#Physical properties:
1. Specific gravity: 1.14
2. Moisture regains: 3.5-5 %( not absorbent due to crystalline).
3. Tenacity (g/d): Dry 4-9, Wet=90% of dry. P.S.I-(60-150)X1000
4. Elasticity: Breaking extension 20-40%.Recovery (%) 100 at 8% very grid of strong H-Bond in the polymer system.
5. Hand: Soft & smooth.
6. Stiffness (g/d):20-40
7. Softening point: Nylon 6-1490C, Nylon6.6-2290C
8. Melting point: Nylon 6-2150C, Nylon6.6-2520C
9. Abrasion resistance: Resiliency-excellent, Dimensional stability –good.
#Chemical properties:
1. Bleaches: Not affected by oxidizing and reducing bleaches but may be harmed by chlorine and strong oxidizing bleaches.
2. Stains: Resistance to water borne.
3. Flammability: Burns slowly, selt-extinguishing melts and drips.
4. Light: There is a gradual tendering minimized by the addition of stabilizer in the fibre. No discoloration take places. For nylon6 gradual loss of strength on prolonged extension.
5. Alkali: Nylon is substantially inert to alkalis.
6. Organic Solvent: Most organic solvent have little or no effect on nylon. Phenol metacressol and formic acid dissolve the fibre but solvents used in satin removal and dry cleaning do not damage it.
7. Biological: Neither micro-organism nor moth-larve attack nylon.
8. Electrical: High insulating properties leads to static charge on the fibre.
9. Other effect: Age appear to have no effect on the fibre. If stored away from light and other deleterious effects, nylon will last for many years.
#The macro structure of nylon: Nylon is a regular, translucent fine filament or staple fibre,
Diameter-14µm to 24 µm. Color-Slightly off white. Length width ratio-2000:1
Polyester Fibre
#Chemical Nature: Polyester fibre are manufactured fibre in which the fibre forming substance is any long chain polymer composed of at least 85% by weight of an ester of dihydric alcohol and terephthaic acid.
Dacron: The fibres are by the polymerization of two monomers terephthaic acid and ethylene glycol.
Trylene: Terylene is made by polymerizing the dimethyl ester of terephthalic acid with ethylene glycol.
Kodel: It is a polymer of 1.4-cyclohexane dimethanol and terephthalic acid.
#Polymer System: Linear polymer D.P=115-140 important groups are -CH2-, -CO-, -OCO- held together by van der waals force, H-bond. Polyester polymer length 120µm and 150 µm and 0.6 µm thick.65%-85% crystalline. Functional group: -OH, -COOH
#The macro structure of polyester: Fine, regular and translucent. Diameter-12µm to 25 µm. Cross section-See the identification part. Length width ratio 2000:1. Appearance: Smooth with round cross-section.
#Special modification of polyester fibre: Non round- Spinneret shape. High tenacity- Drawing/Stretching. Crimped- Uneven cooling at spinning. Thick, thin & slub effect- Uneven. Optical white- Adding fluorescent compound. Low pilling. Reducing D.P. Binder fibre for non-woven- Low melting points sticks at 165oF. Low elongation- Used with cotton in blend.
#Physical properties: Specific gravity – Dacron (1:38), Kodel (1:22). M.R- 0 to 0.4% Hydrophobic for extremely crystalline and lack of polarity. Tenacity-PET= Regular (4.5-5.5), High tenacity 15%, Staple 35%, Kodel 30%.
#Chemical properties:
1. Heat: The fibre becomes tacky at 2350OC and melts at 2500OC.
2. Bleaches: Not affect by oxidizing or reducing bleaches.
3. Stains: Resistance to water borne.
4. Flammability: Burns slowly will shirnk away from flame, yet will exhibit melt drip.
5. Dye ability: Disperse and azoic dyes and some figments are used.
6. Light: There is some loss of tensile strength over prolonged exposure but no discoloration.
7. Acids: Polyester is very resistant, even to mineral acid and thus has this advantage over the polyamides concentrated sulphuric acid disintegrates the fibre.
8. Alkali: The fibre is very resistance although an ester, the relatively impenetrable structure restricts alkaline attacks to the surface. Strong hot alkalis result in a slow thinning of the diameter by saponification.
9. Organic solvents: Adequate all-round resistance including dry cleaning solvent.
10. Biological: Immune to micro-organism and larve.
11. Electrical: Polyester fibres have excellent insulating power. This together with low regain results in the buildup of static charge, vales the latter is suitably dissipated.
12. Other: It is essential to control both laundering and drying temperature to prevent the formation of undesirable wrinkles.
Spandex Fibre
Lycra Fibre
At least 85% by weight of segmented polyurethane
HO-Polyester-OH + OCN-R-NCO Di-isocynate = - [CO-NH-R-NH-COO-R’-O-]-
R= Ether or ester (Soft segment)
R’ = Diphenyl methane (Hard segment)
#Mechanism: The coiled soft segments are straightened out when fibre is stretched. When it is released they coil.
#Commercial name: Lycra, Blue-c, Vyrene, Numa, Spanzelle unit.
#Cross-section: dumb-bell (air space inside)
#Uses: Stretch fabrics, foundation garments and swimware.
#Physical properties:
1. Tenacity (g/den): Low strength: 7
2. Stretch: 500% elongation at break.
3. Dimensional stability: Do not shrink in water with temperature.
4. Moisture regains: 0.6%
5. Specific gravity: 1.21 to 1.35
#Chemical properties:
1. Effect of bleaches: Resistance below at 150OF.
2. Acid & Alkalis: Resistance to acid, some discolor, damaged by hot alkalis, poor conductive.
3. Organic solvents: Resistant to all.
4. Sunlight and heat: Resistance to light. High temperature reduces elasticity. Melt 230OC.
5. Dye ability: Acid, disperse and chrome dyes are used.
6. Flammability behavior: Burns slowly, forms gummy residue.
7. Electrical: Low conductivity.
8. Thermal: Poor conductor.
