chapter 2-4 definition and related terms -...

The attributes of fibers

Chapter 2-4

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DEFINITION AND RELATED TERMS

Textile fiber : should have at least 5mm length then it will be spin able and it must be supple, flexible and strong enough .

Other properties like elasticity, fineness, uniformity, durability , luster and crimp should have a textile fiber more or less

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Before synthetic fibers were developed, artificially manufactured fibers were made from cellulose, which comes from plants. These fibers are called cellulose fibers.

Synthetic fibers are made from synthesized polymers or small molecules. The compounds that are used to make these fibers come from raw materials such as petroleum based chemicals

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The first fully synthetic fiber was Nyloninvented by Wallace Carothers (Du Pont, 1935)

"as strong as steel, as fine as a spider's web”

DuPont touted its new fiber as being

a brand new chemical textile fiber --derivable from coal, air and water – and characterized by extreme toughness and strength –”

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May 15 1940 - “Nylon Day” .

Four Million pairs go on sale

throughout the U.S. Supply exhausted in 4 days.

Dupont first announced and demonstrated nylon and nylon stockings to the American public at the 1939 New York World's Fair.

5 6She couldn’t wait! 6

CLASSIFICATION

The characteristics of the fiber differ depending on the source rom where it is produced. Generally textile fibers are classified into main two types they are – Natural fiber and Manmade fiber (or artificial fiber).

Natural fiber : produced naturally. The source of origin could be vegetable, animal and mineralorigin.

ex. Vegetable : Cotton, Ramie, Hemp, Kapok, Kenaf

Animal : Wool, Cashmere, Alpaca, SilkMineral : Asbestos, Basalt 7

- Cellulosic : Rayon, TENCEL

- Cellulose ester : Acetate

- Protein : Soybean, Casein, Corn

- Miscellaneous

- Polyamides : Nylon- Polyester : PET, PTT- Polyolefines : PP- Polyurethanes

(Elastomer)- Miscellaneous

Synthetic polymer based

Natural polymer based

Man-made fibers

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CLASSIFICATION

World Fiber Consumption trend over the years.(Source: Lenzing Group)

Synthetic fibers passed the natural fiber and are still expanding!

GLOBAL FIBER MARKET TRENDS

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Upward trends for Synthetic FibersThe total market of synthetic fiber segment was about 40.3 mill. tons (57.2%) in 2009

Natural fiber, 37.4%

Cellulosic fiber, 5.4%

Polyester, 45.2%

Polyamide, 5.0%

Polypropylene, 3.7%

Acrylic, 2.7%

Polyurethane, 0.6%

Global fiber production exceeded 70 mill. tons in 2009


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Synthetic Fibers : Polyester - ~80%

Polyester, 79.2%

Polyamide, 8.7%

Polypropylene, 6.5%

Acrylic, 4.7%Polyurethane,

1.0%


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World Fiber Market 2011 shows dominance of synthetic fibers.

- Manmade fibers segment has witnessed considerable expansions in polyester spinning and texturing, nylon filament in particular in China and viscose staple fiber. - Experts assume that cotton production will not be able to be raised to the same extent as in the past, due to the limited availability of arable land.


Fiber production volume in the world textile industry in 2011 rose by 6.4% to 85.9 mill. tons.(Textile fiber review)

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Physical Properties of fibers

Fiber Length

1) The length of cotton fibers is the order of 12 to 36 mm whilst the wool fibers are from 50 to 400 mm long.

2) The common draw back of natural fiber is shorter fibers where many loose ends remain disoriented in the yarn.

3) A staple fiber can have a length of between 10 to 500 millimeters

Short staple fiber has a maximum length of 60 millimetersLong staple fiber has a length of more than 60 millimeters

Synthetic fibers are produced in the form of continuous filament so it can cut into predetermined length.

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Fiber Strength:

The fiber strength measurement is made by clamping and breaking a bundle of fibers from the same beards of fiber that are used for measuring fiber length. ex. Tensile test (Instron)

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Fiber Fineness:

Fineness denotes the size of the cross-section dimensions of the fiber. The Index of fineness which is more commonly used is the linear density or weight per unit length of the fiber.

Micronaire Value (Cotton) :The unit is micrograms per inch. The average weight of one inch length of fiber, expressed in micrograms(0.000001 gram).

fiber fineness (fiber diameter) has a significant influence on the dyeing properties of fiber

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Fabric Lusture:

Fabric lusture depends on some factors

1) Fiber diameter2) Fiber Cross- sectional shape

Fabric lusture is depends on light is reflected from the surface of the fabric.

The ribbon like structure of unmercerized cotton fibers gives a low-lusture fabric.

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unmercerized mercerized


Filament number:

The higher number of filaments increase reflection and refraction: → light scattering ↑, → lower color strength

cf. 70d/26f, 70d/34f, 70d/68f

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TiO2 decrease color strength of dyed fibers(Br : 300 ppm, SD : 3,000ppm, FD: 1.5~2.0%)

=0.03% = 0.3%

TiO2 ↑ → Incident light collide with not only with colorant but also with TiO2 (white pigment) → reflect more white light, lower color strength

TiO2 concentration

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cf. Bright : Most incident light collide with colorants → higher color strength

Morphological features of fibers

The cotton fiber is a single-cell structure and it appears as a flat ribbon like structure and natural convolutions along its length.

The outermost layer of the fiber is the thin waxy cuticle, most of the fiber mass is present as the secondary wall. It consists of spiraling fibrils and varies from 20-300 near the primary wall.

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Structure of the Cellulose molecule

O

OH

O

OCH2OH

OH

OH

O

O

OH

CH2OHO

OH

CH2OH

n

Degree of Polymerization:

The degree of polymerization, or DP, is usually defined as the number of monomeric units in a macromolecule or polymer.

O

OH

OH

CH2OH

OH

OH

H

O

HOH2C

OHOH

OH

OH

-H2O

O

OH

OHOH

CH2OH

O

OCH2OH

OH

OHOH

β-glucose

Cellobiose

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Wool fiber has overlapping scales which give the fiber roughnesswhich creates the friction between fibers in a yarn, thus contributing to its strength. The friction is greater in the direction of tip to root

The distribution of the orthocortex and the paracortex in a wool fiber

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The surrounds the bulk of the fiber material which contained in the cellular cortex beneath. The cortex is two structures 1) Ortho Cortex 2) Para Cortex.


Para cortex

Ortho cortex

The outer scale cells are thin structures that form the main component of the wool fiber cuticle.

Chemical structures of the wool fiber

Amino acids

The most important crosslink's are the sulphur containing disulphide bonds, which are formed during fiber growth by a process called Keratinization.

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Wool set mechanism.

Chemical structures of the wool fiber

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General Characteristics of cotton and wool fibers

cotton wool

Chemical structure

Hydroxyl(-OH)groups

Several different kinds of hydrophilic

groupBoiling water&

ironing Safe Harsh and scorch

Warming(static air) High Normal

Burning Bad Good

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Silk

- Extruded from two spinnerets, one on each side of the head of the caterpillar, as a pair of continuous filaments between 3000 and 4000m in length, joined together by a gum called serecin.

- The gum is removed during processing to release the individual filaments, which have a triangular cross-section and a smooth surface.

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- Produced as a cocoon by the larva of the silk moth Bombyx mori

World War II, The traditional silk filaments were unobtainable

Carothers synthesized a polymer and adapt its chemical structure to obtain a material with specified physical properties ; nylon 66

Long chain molecule-monomer : macromolecules (by Staudinger)

Molecular structures of fibers

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Definition

- A large molecule made up of chains or rings of linked monomer units.

- Polymers usually have high meltingand boiling points.

Polymer :

- Meaning "many parts," it is a material constructed of smaller molecules of the same substance that form larger molecules.

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Definition

PolymerizationMonomer Polymer

Mono: one Mer: unit Poly: many Oligo: several

Terminology– dimer: two units– trimer: three units– tetramer: four units– polymer: many units– pre-polymer: growing towards being a polymer– oligomer: few units fixed in size

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Characteristics

chemically : can be dyed, oxidized, degradable

Physically : can be solubilized and crystallized

Mechanically : can be elastic deformable and oriented

Most of them are Organic polymers

Requirements Long chains of monomers : Molecular weight(Mn) ~20,000 parallel arrangement of molecules cohesive powers between molecules

Characteristics of Polymers

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Properties of Polymers:

The physical properties of a polymer, such as its strength and

flexibility depend on:

1. Chain length - in general, the longer the chains the stronger the

polymer;

2. Side groups - polar side groups give stronger attraction between

polymer chains, making the polymer stronger;

3. Branching - straight, unbranched chains can pack together more

closely than highly branched chains, giving polymers that are more

crystalline and therefore stronger;

4. Cross-linking - if polymer chains are linked together extensively by

covalent bonds, the polymer is harder and more difficult to melt.

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Temperature effect on the polymer properties : cf. monomer

→ Polymer chain entanglement

• Temp. > Melting points : chains move freely• (Tg<)Temp. < Melting points : chains move slowly

→ Flexible but cannot be easily stretched.• Temp. < Glass transition point(Tg) : chains cannot move

→ become rigid


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