Chapter 2. Textile Fibers

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Fiber

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a fine, hair-like substance, the basic unit used to produce fabrics

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Fiber sources

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A. natural – from plants (cellulosic) or animals (protein) or minerals – processed for use as fiber but otherwise not altered. Some of the most common natural fibers

B. Manufactured

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A. natural

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plants –

from seed - cotton

from stem (bast fibers) -- flax, ramie, hemp, jute, bamboo

from leaf – sisal

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A. natural

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animal -

from hair - wool, vicuna, cashmere, mohair

from cocoon – silk

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A. natural

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minerals – asbestos (no longer used)

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cocoon

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B. manufactured

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engineered and produced by chemical companies in factories, extruded through a mechanism called a spinnerette. Most manufactured fibers are petrochemical products (plastics), but others are manufactured from natural components (i.e., although most rubber is now synthetic – latex – rubber fiber can also be manufactured from the sap of the rubber tree).

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spinnerette

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喷丝板

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petrochemical

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* adj. 石化的
* n. 石油化学产品

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Fiber structure

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A. fiber length

B. fiber shape

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A. fiber length

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1) staple – fibers whose length can be measured in inches a) all natural fibers are staple except silk

2) filament – fibers of continuous or indefinite length

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2) filament – fibers of continuous or indefinite length

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a) all manufactured fibers and silk are initially filament fibers

b) they can be cut to staple length to change way finished fabric will

look and feel

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B. fiber shape

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1) shape determines bulk, texture, luster and hand – affects fiber properties.

For example, wool fibers are round, resulting in bulkier fabrics.

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4. Fiber properties ( A-R)

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fibers possess basic characteristics, and these properties determine whether a fiber is appropriate for a particular end use.

For example, an undershirt should be absorbent. Therefore, cotton would be desirable, but nylon would not be desirable.

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A. abrasion resistance

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abrasion resistance — resists wear from rubbing, leads to fabric durability

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B. absorbency

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ability to take in moisture, measured in terms of moisture regain – atmospheric moisture absorbed at 70° F and 65% relative humidity over a testing period of 48 hours

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B. absorbency

i

ii

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i. hydrophilic fibers absorb moisture readily (all natural fibers plus some manufactured ones)

ii. hydrophobic fibers do not absorb moisture readily (all manufactured fibers are hydrophobic with the exception of manufactured cellulosic fibers, i.e. rayon, lyocell, acetate)

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B. absorbency

iii

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some effects of absorbency

1. increases skin comfort

2. decreases static build-up – lack of absorbency causes sparks, static cling

3. dimensional stability - hydrophilic fibers shrink more

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B. absorbency

iii

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4. stain removal - easier in hydrophilics because they absorb detergents

5. water repellency - better with hydrophilics since they absorb finishing chemicals

6. wrinkle recovery - better in hydrophobics

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C. chemical effects

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especially important when related to care of end product

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C. chemical effects

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1) cotton becomes weaker when treated with certain resins

2) wool and silk are damaged by chlorine bleach but not peroxide bleach

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D. cover

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ability to occupy an area – affected by fiber shape.

Crimped fiber covers more area than straight fiber.

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E. dimensional stability

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degree to which fiber will shrink or stretch.

The dimensional stability of a fabric can be also affected by type of yarn used, knit or

woven structure, and fabric finish

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E. elasticity

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- ability to elongate (stretch) and recover to original length

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E. elasticity

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1) leads to comfort, less seam stress and less bagginess

2) spandex is very elastic - elongates much more than 100% of original length (elastomeric fiber)

3) unrecovered stretch is called growth or creep

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E. environmental effects

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these can make some fibers unsuitable for certain uses

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E. environmental effects

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1) protein fibers (i.e. wool and cashmere) can be attacked by moths

2) cellulosic fibers (i.e. cotton) mildew

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E. environmental effects

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3) nylon and silk are weakened by sunlight

4) acetate is subject to atmospheric gas fading

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H. flammability

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1) flammable fibers relatively easy to ignite

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H. flammability

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2) flame-resistant fibers require high ignition temperature

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H. flammability

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3) fireproof fibers will not burn

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H. flammability

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4) self-extinguishing fibers will not continue to burn if removed from flame

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H. flexibility

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ability to bend repeatedly without breaking – drapability

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J. hand

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– the feel of a fabric. The shape of fiber, type of yarn, fabric construction and finishes affect hand

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K. luster - 光泽

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amount of light reflected from a surface. Determined largely by fiber shape (flat surfaces reflect the most light), though manufactured fibers can be made more or less lustrous by adding chemicals.

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L. pilling

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groups of short, broken fibers which ball together on surface of fabric. A

fiber’s pilling propensity can make it undesirable for a particular use.

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L. pilling - 起毛粒，起毬

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1) hydrophobic fibers pill more than hydrophilic ones because static causes fibers to be attracted to each other; strong fibers pill more than weak ones since weak fibers will simply break free of the fabric surface

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L. pilling

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2) wool fibers pill due to scaly surface of the fiber

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L. pilling

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3) lint pilling occurs during laundering

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M. resiliency

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- ability to spring back to shape after being creased, twisted or distorted – wrinkle resistance

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density (specific gravity)

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weight of fiber compared to water

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density (specific gravity)

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1) fibers with lower density are lighter in weight

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density (specific gravity)

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2) if fiber density is less than 1.0, fiber will float (i.e., olefin)

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density (specific gravity)

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3) density of wool - 1.30; acrylic 1.16.

Acrylic is used to make garments which weigh less than comparable wool garments.

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O. static electricity

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caused by friction, affected by fiber absorbency

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O. static electricity

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1) causes clinging - attracts lint

2) discharge of electricity causes a shock

3) mostly a problem with hydrophobic fibers

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P. strength

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- leads to fabric durability.

Strong fibers require less fiber to produce a yarn - fine yarns can be used to produce sheer fabrics (i.e. nylon hosiery).

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Q. thermoplasticity

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- fiber softens when subjected to heat

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Q. thermoplasticity

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1) most manufactured fibers are thermoplastic

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Q. thermoplasticity

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2) heat is commonly used to impart crimp to fiber and to create permanent

creases or pleats in garments

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Q. thermoplasticity

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3) shape can be imprinted on fabrics made of thermoplastic fabrics,

resulting in greater dimensional stability

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R. wicking

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ability to transfer moisture from one section of the fiber to another,most importantly from the skin to the outer surface of the garment where moisture can evaporate – important for skin comfort.

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R. wicking

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1) moisture travels along surface of fiber but is not necessarily absorbed by fiber

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R. wicking

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2) some fibers that absorb moisture also have wicking qualities (cotton, flax)

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R. wicking

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3) olefin, though hydrophobic, has excellent wicking capabilities

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R. wicking

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4) polyester can be designed to have superior wicking capability, i.e. the

polyester fiber used in Cool Max® fabrics

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5. Methods used to identify fibers

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(these are handy but very rough tests – if you really need to know what a yarn or fabric is made of, you should send the sample to a professional lab for analysis.)

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A. burning test

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1) can identify general fiber content (protein, cellulosic or thermoplastic) by

a) whether sample burns or melts or both

b) odor

c) residue

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A. burning test

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2) limitations of burning tests

a) burning behavior may be affected by fabric finishes

b) odor may be masked by finish used

c) use of blends makes identification difficult

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A. burning test

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3) general burn characteristics

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A. burning test

3) general burn characteristics

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a) cellulosic fibers burn, have an odor of burning paper or wood, and leave a grey ash residue

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A. burning test

3) general burn characteristics

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b) protein fibers burn but will not sustain combustion when the source of flame is removed, odor is of burning hair, and residue is a

crushable black bead

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A. burning test

3) general burn characteristics

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c) most thermoplastic fibers burn as well as melt, and their residue is a hard, uncrushable bead

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B. acetone test

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– identifies acetate only