Evolution of Man-Made Fibers

8 Evolution of Man-Made Fibers

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Κ Ε. MAGAT and R. E. MORRISON Pioneering Research Laboratory, Textile Fibers Department, Ε. I. du Pont de Nemours & Co., Inc., Wilmington, DE 19898

Let us take a short trip through what may be called the golden age of man-made fibers. This review of man-made fibers deals only with fibers prepared from organic intermediates and does not include fibers spun from cellulosic derivatives. It all started with the discovery and commercialization of nylon in 1940 and reached the point today where noncellulosic man -made fibers account for more than half of the total fiber consumption and are expected to reach about two -thirds by 1980 in the United States. The scenario can be divided into four phases: Phase 1 - 1940-1950 - Development of nylon and i n tensive exploration for new fiber-forming polymers. Phase 2 - 1950-1956 - Introduction and commerciali zation of major man-made fibers beyond nylon. Phase 3 - 1956- Development of second generation fibers. Phase 4 - 1960- Development of specialty fibers. Research on the last two phases is today.

still

going strong

Phase I With the discovery of nylon and its commercial introduction, fiber research all over the world shifted to a search for other synthetic polymers capable of forming fibers. I n i t i a l l y , the objectives 127

Arthur; Textile and Paper Chemistry and Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1977.


128

TEXTILE AND PAPER CHEMISTRY AND TECHNOLOGY

were twofold. (1) To duplicate the properties and feel of natural fibers, the resilience of wool, the luxury of s i l k and the versatility of cotton. (2) To develop a relationship between fiber structure and chemical composition with fiber properties. Literally hundreds of polymers were prepared during this period and spun by the new melt spinning process specifically developed for nylon and by wet or dry spinning used for cellulosic derivatives. The f i r s t target met by nylon was the s i l k hosiery market leading ultimately to nylon monofil hosiery. Following the overwhelming acceptance of nylon hosiery a second "natural" end-use was tricot capitalizing on its excellent k n i t t a b i l i t y and durab i l i t y resulting in penetration of a major rayon and acetate stronghold. Another major penetration was in tire cord based on nylon's high strength, impact resistance and a b i l i t y to withstand repeated flexing and stresses. A variety of other polyamides were examined and except for 6 nylon which was developed in Germany, 6-6 nylon emerged as the major polyamide candidate from this era. Research turned in the direction of polyesters and vinyl polymers. Two major fibers emerged from this intensive search, poly(ethylene terephthalate) and polyacrylonitrile. Building on Carothers' work the discovery of poly(ethylene terephthalate) fibers by Whinfield and Dixon in England opened the door to a new fiber which could u t i l i z e much of the melt spinning technology developed for nylon. The polyacrylonitrile breakthrough came with the discovery of a solvent which could dissolve this heretofore intractable polymer and thus yield spinnable polymer dopes. With the preparation of hundreds of polyamides, polyesters and polyacrylics, a sound basis for correlating structure and fiber properties was established, opening the door to Phase II.


8. MAGAT AND MORRISON

Evolution

of Man-Made

129

Fibers

Phase I I As

we

fibers nylon

plants

fibers

tinuous

filament

yarn

The existing

as Orion®

Dacron®

polyester

objective

continued

markets.

The v e r s a t i l i t y

leading

depending

or rayon

Polyacrylics

rapid

and

blankets.

for

wool-like

and

polypeptides

fibers

t h e door

the fourth

The

into

which

of

soon

simulated

wool,

conditions.

i n sweaters, that

centered

out t o be b e s t

on

carpets the

search

polyamides

met b y

none

the discoveries

poly-

of the chemical

to isotactic

o f Z i e g l e r and

polypropylene

polyolefin fiber

major

research

those

striking

of polyester

remarkable

initially

which

candidate

and

fiber. and e v a l u a t i o n

l e d to fabrics with

exceeding

went

o f wool.

as t h e major

Intensive fibers

plant

of the characteristics of

acceptance

turned

t h e mid-50's

opened

became

as con-

i n 1952.

processing

and p o l y a c r y l i c s which have

emerged

most

upon

I t i s indeed

characteristics Natta

started

t o be t h e p e n e t r a t i o n

to fibers

s h o w e d many

and found

In

Three

Polyacrylo-

i n 1953.

cotton

esters

o f man-made pace.

i n 1950 a n d s t a p l e

became a p p a r e n t

wool

rapid

i n operation.

introduced

commercial

operation

1950, t h e g r o w t h a t a very

were a l r e a d y

nitrile first


approached

was p r o c e e d i n g

unique

o f these

four

characteristics far

o f f a b r i c s from n a t u r a l

fibers.

The

o f these a r e :

(1)

wash-wear

(2)

resistance

to wrinkling

and r e c o v e r y

from

wrinkling (3)

durability

(4)

heat

settability.

These

unusual

areas

and p r o v i d e d

of

the four The

wet be

major

first

standing

properties

entirely

washing

properties

For the f i r s t

wrinkling.

could

end-use growth

fibers.

time

Wrinkles

be removed

from

of polyester

simply

the out-

fibers,

some g a r m e n t s

worn a l l day i n d r y and wet weather

excessive

new

f o r further

two c h a r a c t e r i s t i c s s t e m

recovery

and d r y .

opened

the springboard

without

introduced

both

could

during

by tumbling the


130


garments

in a dryer.

achieved

not

of

only

polyesters with

ester

with

fabric

w h i c h made t h e

be

with

Blending the

blends

of

poly-

degree

of

permanent-press

possible.

of

of nylon

magnitude t o

Boys'

jeans

out.

The

could and

Heat

Heat

and

imparts

formation. boarding

setting

carpets

any

of

It started

t o be

nylon

and

with

their

the

leading to

is

new

worn

indeed

fiber.

out

a memory o f

of hosiery

a

apparel.

outworn r a t h e r than

turned

t o permanent p l e a t s and the

be

unmatched by

attribute.

polyesters provided

of nylon

settability

fabrics

and

longevity of wearing

finally

durability

remarkable

of

wool.

but

resin-treated cotton provided

Durability


polyester alone

c o t t o n and

strengthening

concept order

These p r o p e r t i e s c o u l d

with

a very

important

polyester original

discovery of

pre-

seamless hose,

creases

and

enormous t e x t u r e d c o n t i n u o u s

now

fibers con-

spread

i s the

filament

basis

yarn

market. Phase

III Having

polyester, research entered coined

shifted into

by

physical

and

the

fibers

properties, nological

as

with the

tailor-made

parent

the

fiber

1956

and second

characteristics. same b a s i c but

to develop on

materials

offering

novel

These

tech-

markets

and

f o r man-made

superimposed

we as

chemical

to prepare

performance.

p a t t e r n was

c o u l d be

fibers.

building

conventional

technology. m o d i f i c a t i o n has

markets where b u l k , quirements. thermal

yarns

able

b a s e d on

In

engineering

appropriate was

i n c r e a s e d demand

general

Physical

such

By

nylon,

fibers,

a d v a n c e s h a v e o p e n e d h u g e new

blocks which

by

direction.

a e s t h e t i c s and

steadily

fiber

a new

of molecular

were d e v e l o p e d

The

polyolefin

P r o f . Mark.

chemistry

have

into era

sound b a s i s w i t h

and

m o d i f i c a t i o n one

generation Fibers

established a polyacrylics

as

Improved b u l k or

false

mechanical t w i s t or

were o b t a i n e d

opened

t e x t u r e and

by

and

luster

up

very

t e x t u r e were

texturing using

jet texturing. combining

large

were prime

re-

achieved

processes

Self-crimping

polymers

with


8.

MAGAT AND MORRISON

different

shrinkage

fibers

i n mixed

or

of

Man-Made

section

modification provided

section

luster

options

industrial zation

attractive and

are

yarns,

new

tensile

giving

led to

Chemical solutions

a l l four basic

t o major

end-use

by

modification of

chemical

examining

h a v e b e e n made advances

i n nylon fibers.

leads pill

poration

of

increased

novel

has

On

other

resistance

dye

and

salts)

antistatic

Sites nylon.

Sites

of

I.

i n Table

stronger

and

hand,

lower

molecular

which

exhibit

fabrics.

sites

had

antioxidants

are

advances Major

and

freedom

resistance

dyes

readily

Incorled

light from

by in

s m a l l amount o f

phthalic

i n place of

fiber,

multicolor

fabric

i n one

is

the

levels

"Sunburst" of

dye

containing and

we

generation many o f

the

development

dye

on

can

acid.

be

bath.

When

combined achieved A

striking

dyed

i n one

single

by

with dye

fiber

modifications is s t i l l

An

o f Qiana®

the

four

bath

dyes. the b e g i n n i n g

example

most d e s i r a b l e

single

illustration

of

fibers.

fibers dyeing

types

are witnessing

co-

sulfoiso-

i n one

carpet containing fibers

affinity

three

Research ing

effects

single

i n c o r p o r a t e d by

adipic are

hiding.

controlled

are

dyeabilities

static

c a r b o x y l ends

f o r b a s i c dyes

acid

copper dura-

soil

f o r example,

different

to

(e.g.,

through

amine and a

be

obtained

fibers

m o d i f i e r s to

for acid

T h i s can

effects

shown

to b e t t e r heat

the balance

of

provided

Similar

led to

b a s i c dye

soil

great deal

polymerizing, with

and

polyacrylics.

i n staple

versatility;

i n some c a s e s

changing

are

weight the

a

and

the

nylon.

technology

acidic

manganese

bility;

some o f

t o more b r i t t l e

improved

added fibers

i n p o l y e s t e r s and

molecular

tougher

and

of

crystalli-

stability

limitations.

by

and

field

and

with

improved

m o d i f i c a t i o n has

to

illustrated

weight

processes

Some c r o s s the

properties.

versatility

Higher

In

Cross-

an

aesthetics.

fibers

with

yielded

bulk. with

i n F i g . 1.

drawing

yarns

These and

fabrics

tactile

sequences have

morphology

aesthetics

shown

i n bicomponent

yarns.

with

131

Fibers

characteristics shrinkage

fabrics

attractive


Evolution

of

a

building

nylon which

of

fiber blocks

continu-

third combining is

the

exemplifies

the




132

Figure 1.

Cross-section versatility

TABLE POLYMER

HIGHER

MODIFICATION

MOLECULAR WEIGHT

INCORPORATION B A S I C DYE

I

OF A C I D I C AND

STRONGER F I B E R S DYE

VERSATILITY

SITES

ANTIOXIDANTS

HEAT D U R A B I L I T Y LIGHT DURABILITY

ANTISTATIC

MODIFIERS

FREEDOM FROM (SOIL

HIDING)


STATIC

8.

MAGAT AND MORRISON

purposeful fications


combination to yield

of

high

fibers.

The

contains

cyclohexane

recovery

p r o p e r t i e s and

polymer

f a r exceeding end-uses. The

tuned

and

filaments

i n a yarn bundle shrinkage

providing fabrics as

capillary Another the

spaces

facet

fiber

gives

w e l l as

a

that bring and

silk-like

with

a myriad

of physical

shape

by

is triggered

finishing,

the

temp-

a

of

in

for

the

f o r garments Qiana®

of

is

polymer

which

have h i g h e r

bulky

feel

feature of

spinning technology

This

high

encountered

combination

fications

which

to give

characteristics

self-bulking

finely

modi-

glass transition

temperatures

of

others.

polyamide

These p r o p e r t i e s account

ease-of-care

a

physical

self-bulking

i s designed

a high

outstanding of

and

for this

rings

erature

Qiana®.

chemical

performance

base

apparel

result

133

Evolution of Man-Made Fibers

the

modi-

some

shrinkage

during rich

than

fabric

handle

and

a

interfilament

about wearer

comfort.

m o d i f i c a t i o n i n Qiana®

particulate

additive

pearlescent luster

is

that

without

chalki-

ness. Another

direction

generation

fibers

structures

by

This sheet has

yarns

been

tinuous agent

and

coarse

we

a

this

initial

shown for

look

fabric.

to polyethylene

the

are

the

third

the

36

survey of

I t took

30

web

bonding

exceed as

fibers

over-all

years

from

t o c a t c h up

with

i n the United

man-made f i b e r s

a

w h e r e a web

o f major

The

1980 to

con-

where a


period.

i s expected

By

a

where

i s bonded w i t h

volume

expected

i n Tyvek®

i n Typar®

as

technology

generation derivatives,

growth

year

noncellulosics

their

This

of

self-bonded.

and at

spinning.

where

interconnected i n a

polypropylene is

new

down d i r e c t l y

t o p o l y e s t e r i n Reemay®

i n F i g . 2.

cotton. are

laid

complete

second

take

1976

spun and

filament yarns

fibers

As their

to

fiber

technology

nonwoven

network,

continuous

integrated with

spunbonded

fibers

of

sheet

or

applied fine

development

preparation of

are

structure

extremely of

a process

i s the b a s i s of

multiple

f o r the

i s the

10

t o be

compared

is

introduction cotton.

twice

lbs. of

to 4 b i l l i o n

during

picture

that

States alone

billion

and l e t us

In of

shipments

noncellulosic l b s . of


134


natural

fibers.

Table grown. and

I I shows how

Polyester

i s now

expected

second

t o be

these high

only

the

the

f a r the to

cotton.

number o n e

volumes the

four

major

By

fiber

1979

advantages of significant

and

these

carpet

total

industry

carpets

will

million

l b s . of wool.

price The

trend

force

In

polyester

equivalent, i s at

a

At

fibers.

nylon

i s quite

of

polyester

16 the

remarkable.

cotton. a

1976

times is

i n 1974

thus p r o v i d i n g

use

vs.

to cotton

time

the

In

inflationary

than

fiber

increased

magnitude.

l b s . of

short

illus-

polyester

Today

strong

they

driving

s t a p l e where

per-

premium.

about

the

same t i m e a s

generation

fibers

with

fibers,

an

entirely

achieved

fication

four basic

These

of

the

fibers

fibers

because

polyesters, yet

are

t h e y do

are

duplicate such as

of

not

have

or

utility

the

rubber,

glass

and

steel

these

E a c h new

chemical

represents product

f o r the

or

contrast

basic

pattern

fibers. was

to

materials

achieve heat

an

extreme

resistance,

resistance. a development

i s the

desired

f i l l

specialty

from b a s i c

c h a r a c t e r i s t i c s such as

f l a m e r e s i s t a n c e and Each of

fibers

of

polyamides

lbs. in

l b s . f o r the

i n i t i a l research of

to

these

of m i l l i o n s of

modi-

specialty

broad

for

properties

systems.

as

designed

of

shifted

physical

fiber

the

Markets

tens

properties

search

set of

chemical generic

m i l l i o n s of

again

performance

itself.

different

by

specifically

i n the

to hundreds Here

attention

p o l y a c r y l i c s , p o l y o l e f i n s , and

they are

development

sometimes r e f e r r e d t o

important market need. fibers

the

research

w h i c h c a n n o t be

sive

the

four

now

compared

a

At

IV

second

but

of

these

as

For

f o r expanded

Phase

billion

a c t u a l l y cheaper

about

formance

to

1.2

i n F i g . 3.

s t a p l e was are

has

o f man-made f i b e r s

price of

trated

w o o l and

several orders

use

enhance

i s a good example where a

competing with

m a r k e t by

i t is

l a r g e - s c a l e manu-

p o s i t i o n of

started

have

fiber

in textiles.

favorable

competitive

fibers

f a s t e s t growing

f a c t u r e become h i g h l y The


fast

i s by

outcome o f

properties,

story an

in

inten-

understanding


MAGAT AND MORRISON


8.

1940 Figure

1945 2.

Evolution

1950

Growth

of Man-Made

1955 1960 YEAR

1965

135

Fibers

1970

1975

of man-made fibers vs. cotton in U.S.

TABLE I I GROWTH OF MAJOR FIBERS

(U.S.)

(MM LBS.)

NYLON

POLYESTER

ACRYLIC

OLEFIN

1950

90

0

1

0

1960

411

75

135

14

1970

1354

1465

491

255

2000

3000

600

500

1976

(PROJ.)

(COTTON:

3600)


136

of


the

mechanical

between fiber four

fiber

properties

chemical

properties. types

stage:

of

high

resistant

and

desired

This discussion

fibers

which

temperature

fibers,

have

be

reached

fibers

correlation

structure will

resistant

elastic

and

physical

the

fibers,

and

with

limited

to

commercial chemically

reinforcing

fibers. High

Temperature


The

f o u r major

ture well apparel for

Resistant Fibers

below

200°C.

end-uses

extended

between

200°

carried

out

fibers

the

the

relationships stability. candidates

are

are

by

linked

Typical

products

Table

III.

dibasic

polyamides. diphenyl zoles

are

and

of

finally,

a

benzimidazole

and

aimed

and

starts

with

a

I f one

an

in a

amide

in and

an

aromatic

tetramine

and

the

polybenzimida-

a diamine

with

is a

with

acid,

the

shown

obtains

i s used

benzene

diamine

product

combines

ther-

for preparing

acid,

uses

tetramine

where

are

one

a dicarboxylic

and

imidazole

aromatic

chloride,

been

defining

heat-resistant

reactions

an

at

structure

polymers

tetracarboxylic

obtained which

ranging

imide

dianhydride, the i f a

or

temperatures

properties

with

obtained. acid

anhydride is

fiber

and

perform

polymer

aromatic

acid

industrial can

ten years

amide,

I f one

ester

aromatic

past

Starting

tempera-

E x t e n s i v e r e s e a r c h has

chemical

and

at

of

which

most p r o m i s i n g

fiber

these

time

between

The

rings

aromatic

needed

400°C.

mal

linkages.

a number

are

periods of over

a maximum u s e

For

fibers

and

have

a

an

polyimide;

a bis

ladder

properties

of

condensed

polymer a

heterocyclic

structure. The

major

commercial

Nomex®

aramid

1961.

I t i s prepared

dibasic

acid

followed

by

Related is

flame

sistance

w h i c h was chloride

solution

nylon

and

be

in this

solution

with

an

polymerization of

aromatic

In c e r t a i n

fully

polyester

in

resistance

requirements

cannot

is

by

fiber

s p i n n i n g from

to heat

resistance.

needs

end-use

introduced commercially

an

amide s o l v e n t .

a highly

are

so

severe

by

conventional

even

desirable

end-uses

met

fibers

that

after

a

diamine

they

flame

goal

re-

performance polyacrylic, are

flame



TABLE HT HEAT RESISTANT FIBERS τ/Ε NH

2 v

x^NH

2

ClOC^^COCl

x ^ . N H - C O ^ ^ .

Η

co^oc

CO^OC

!


Î

9

P

d

/

%

)

138


retarded.

These

structures

which a r e d i f f i c u l t

relatively

high

Nomex® Fibers and

dictate

meets

this

and

requirement

tection

Nomex®

i s now b e i n g

clothing

from char

In total

certain

extreme

exposure

Nomex®

III.

a

new

nology.

uses

This

aromatic

exhibit

very

important

fabric

A by

and

The

i s based

precursor

fusible,

For

flame

beyond insulation

spinning

heat

thereby

flux,

on

tech-

Nomex® I I I

open and

maintaining

ana i r

characteristics

with

such

t o as

i n 1971 i s b a s e d

no s a c r i f i c e

as comfort,

of

of

abrasion

resistant

fiber

i n 1970.

i s a novolac

formaldehyde

was

introduced

The f i b e r

named

phenol-formaldehyde. which

and cured

i s later to give

posta non-

fiber.

Resistant Fibers

certain

a very

1960

Teflon®

the high

as

of

t o supplement

referred

on a c r o s s l i n k e d

fiber

with

with on

such

these

total

fiber

The p r o t e c t i o n

nonflammable

Chemically

key

t o high

attributes

pro-

coloration.

new h i g h

crosslinked

Under

a n d o n new

t h e C a r b o r u n d u m Company

"Kynol"

protection

i s now

low s h r i n k a g e ,

unique

i s the key.

a new

I I I have been o b t a i n e d

resistance

exposures

s t r e n g t h , do n o t b r e a k

layer.

of a

a thick

flame.

introduced

When s u b j e c t e d maintain

Nomex®

fiber

uses,

Pro-

lightweight fabrics

flux

which

polyamide

fabrics

insulating

produces

open thus

Du P o n t h a s d e v e l o p e d f o r such

and i n d u s t r i a l

i s desired.

heat

smoke

o f i t s flame

in aircraft.

conditions short-term

high

Nomex®

to a

degree.

little

i s the r e s u l t

which

i n flames,

b y Nomex®

extremely

to

e x t e n s i v e l y used i n

c a t a s t r o p h i c flame

s h r i n k and break

offered

from

by Nomex®

behavior

to a high

generate

formilitary

upon exposure

immersion

Nomex® that

flame

and f a b r i c

tective

polymer

and s t a b l e

As a r e s u l t

i n c a r p e t i n g and u p h o l s t e r y

fiber

with

to ignite

to ignite,

are self-extinguishing.

resistance,

fibers

temperatures.

are d i f f i c u l t

protective


end-uses

high

industrial level

fibers

end-uses

o f chemical

were

fibers

a r e needed

resistance.

introduced which

In

capitalized

inertness of polytetrafluoroethylene.

a d v a n c e was

the discovery of technology

The

f o r con-


8.

MAGAT AND MORRISON

verting

an

ethylene of

Elastic

and

In

the

put

be

Thus,

one

the

polymers

would

viscose

solution

for a

not

linear

have

to

rubber.

by

was

toughness. selected

as

block

giving

the

scheme

i n Table

To

form

cyanate

to

final

give step

an

hydrazine

product

or

a

i s a high

the

the

the

molecular polymers

fibers

can

of

Lycra® soft

type

hard

are

of

block, of

final

The is

the

soft

aromatic

diiso-

prepolymer. polyurethane

chain

extension

reaction

polymer

having

urethane

soluble

in

be

were

intro-

fiber

form o f

readily

at

prop-

was

segmented

weight

reinhigh

segment.

terminated

The

as of

product

segment by

i n the

act

polyurethanes

excess

the

diamine.

linkages.

These

this

hard

sites

and

1958

an

i n preparing

hydrogen bonding solvents

In

isocyanate

synthesis of

segment

program aimed

as

for preparing

i s end-capped w i t h

polymers

hard

elastomer

balance

polyether

TV.

an

is

alternating

melting The

extensive

segment

the

high

as

of

crosslinking of

composition,

processibility. a

feature

segment m a t r i x

best

fibers polymers.

crosslinking

without

to g i v e

an

best

utilizing

general

soft

particles

Following

the

and

"hard"

in a

to

consist

amorphous p o l y m e r s .

filler

erties

of

stable

elastic

essential

They

blocks

and

that

resort

The

fibers

defining

with

spinning

followed

non-crosslinked

elastic

or

strong

was

nature.

forcing

is

wet

use.

sheer,

finding

from

domains d i s p e r s e d

The

on

dispersion

commercial

giving

"soft"

shown

polytetrafluoro-

in a

segmented

segments

duced

as

based

key

prepared

conventional

with

such

process

Teflon®

139

Fibers

A

the

to

search

fiber

could

their

of

Man-Made

polymer

fiber.

dispersed

of

Fibers

elastic


a

coalescence

developed

in

intractable

into

Teflon®

heat

Evolution

or

urea

amide

prepared

by

dry

spinning. This has

been

segment

general refined

structures of

aromatic

the

functional

This and

has

polyethers a

using and

variety

resulted in fibers

mechanical

hydrolytic

elastic

years

d i i s o c y a n a t e s and

tenders. color,

pattern of over

fiber

formation

optimum

soft

polyesters, of of

chain

ex-

improved

p r o p e r t i e s i n c l u d i n g improved

stability

and

UV

stability,

high



Extension

0

II

c-o

+

Η

Η

Η

+ H N - R ' — NH

Ο

2

OH

Η

Ο

II

Η

Η

I

Η

O - C - N - R - NCO

- CH

2000

2

ο

•«

ο

»

ο

H

ο

il

O-C-N-R-N-C-N-R'-N-C-N-R-N-C-O-

Η

~

2

OCN-R-NCO

MW

2

H Ο - CH CH CH

OCN - R - N - C - O

Macroglycol

Segment

Capping-

Chain

End

Soft

TABLE I V


ο

Ι -Q~C „

,

, V

ο

1

MAGAT AND MORRISON

8.

power, h i g h

e l o n g a t i o n and

Reinforcing

Fibers

A

rapidly

fibers

i s the

reinforcement technology fibers.


through

a

and

suitable led

to

not

be

steel and

new

fibers of

met

with

The

new

high

Kevlar®

aramid,

ideally

suited

fiber

this

high

are

has

shown

modulus o f vides

a

the

The

provided

new

thus

curves

of

1

l b . of

shown

Kevlar®

polyester,

or

only

one

belt

yarns

tire

yarn

must

flex

life

and

these

5

stiffness

ease

requirements Reinforcement

fibers

i s receiving

of

rapidly

the

posites. yield

offer

On 2

of of

Reinforcement

advanced

a

remarkable by

tire

of

composites

strength, nylon

of

or

is

yarn.

For

importance.

The

adhesion,

Kevlar®

meets

degree.

continuous

technology

pro-

are

Tensile strength

increased attention

growing

and

density fibers

good b a l a n c e

resins

organic

glass,

processibility.

to a

properties

the b a s i s of

lbs. of

i s o f major a

an

a fiber,

Tensile

for tire

l b s . of wire.

also

they

reinforcement

i t s low

consideration in selecting high

and

strength

superiority.

replace

of

tire

high

with

i n F i g . 5. can

glass

steel. The

combined of

levels

affording

strength-modulus r e l a t i o n s h i p s graphically

and belts

introduction of

major

i n F i g . 4.

strong margin

Glass

for tire

While

has could

desired properties,

to glass or

Kevlar®

them

tires

m o d u l u s man-made o r g a n i c

for tires,

Stress-strain fibers

subse-

fibers.

market.

limitations.

alternative

were

t o make

radial

required stiffness

tenacity,

rayon, were

p e r f o r m a n c e demands w h i c h

captured

their

rein-

fibers

but

processing of

tire

for

progressing

including

these

organic

The

markets

the

c o t t o n and

advent

existing the

largest

applications

special

c o n t r i b u t e some o f have

with

filament

resins.

is a well-established

the

In general

for tires.

stringent

of

and

synthetic fibers

for textile by

rubber

have dominated

series

polyester.

provided

steel

one

starting

rapidly

also

provides

adapted

f o r continuous

of

for tires

field,

engineered quently

recovery·

market

of rubber

Organic

forcement nylon

expanding

high

reinforcement

and

141


of

filament the

advanced

thermosetting initially

as

basis com-

resins

started

with


to con-



STRAIN (%) Figure 4.

Tire yarn stress-strain

curves

KEVLAR®

NYLON POLYESTER f

QGLASS

RAYON •WIRE

100

200

DENSITIES NYLON POLYESTER KEVLAR® GLASS WIRE

_L_

300

_L

400

1.14 1.38 1.45 2.55 7.9

500

600

MODULUS (gpd) Figure

5.

Tensile

strength-modulus fibers

rehtions

for

tire


8.

MAGAT AND MORRISON

tinuous ratio of

filament glass.

of

tensile

structural High

major

modulus

With

at

fibers

lower of

of preparing

the

Kevlar®

organic

fibers

stress-strain Fig.

strengths

more r e a l i s t i c composites

of

tensile

as

the

third

these

matrix

high

as

aluminum

to

to

improve

atures. fibers

Let

us

properties fibers

are

polymeric

a

fibers. filament

converted reach to

as

the

such and

temperas

preparation

main

flameproof

Orion®.

and

a temper-

polyof

carbon

(PAN)

continuous-

Three process

the

steps

carbonization first

step

the

and PAN

structure originally

Carbon

highest

1400-1800°C

In

of

high

properties obtained

pretreatment,

treatment.

and

Graphite

source

polyacrylonitrile

their

well

fibers.

Cellulose

the

to graphite yarns. thermal

known a s b l a c k

i s to

filament

decomposition

i l l u s t r a t e s the

to a

elevated

f o l l o w e d by

graphite.

have p r o v i d e d

high-temperature

heated

at

thermal

of

metals

drive

i n metals

continuous

Kevlar®

carbon

involved:

process

look

and

to

yarns

using

The

fibers

intensively

by

upon c o n v e r s i o n

specific reflect

boron

prepared

Fig. 8

A

advanced

strength vs.

properties at

quick

to

for

reinforcement

precursor

conversion

fibers

fibers.

graphite

acrylonitrile

compare

cross-section.

stiffness-to-weightratio

explored

take of

in

to

These values

stiff

g r a p h i t e and alumina

with

weight.

tenacity,

are being

experimental

named

shown

used

in i t s infancy.

increase

the

weights.

Comparative are

equal

these

fiber

retention of

Here

of

equal

is still

incorporate

fibers

specific

of

possi-

Kevlar®

u n i t s are

of

sparked

the

compete d i r e c t l y

i n F i g . 7.

area

have

matching

application.

comparison

shown

of

is

stiffness.

boron

composites

now

fibers

properties at

The

ature

of

i s to plot

stiffness

are

in this

curves

glass

in

offering

a variant

fibers

ratio

properties of

c o n s i d e r a b l y lower

6 where p s i e n g i n e e r i n g

tensile

as

at

by

high

a high

While

g r a p h i t e and

introduction of

inorganic

the

143

is a

and

weights.

advanced

of metals

49,

goal

i t i s somewhat d e f i c i e n t

materials/design revolution

properties


The

Fibers

strength-to-weight

metals

strong,

bility

is

of Man-Made

stiffness-to-weight to achieve

quite a

Evolution

fibers

tensile

( G r a p h i t e HT)*

made b y

the

PAN

s t r e n g t h when There

is


direct



600

TENSILE STRAIN (%)

Figure

6. Stress-strain

behavior

of reinforcing

fibers

"KEVLAR"49

"S"-GLASS

HT G R A P H I T E

BORON H M GRAPHITE* φ "Ε"—GLASS

1

2

3

DENSITY (gm./cc.) "KEVLAR" 49 1.45 GRAPHITE HT 1.78 GRAPHITE HM 2.0 BORON 2.68 "S"-GLASS 2.48 _L 4 5 6

7

SPECIFIC T E N S I L E MODULUS (10 IN) 8

Figure

7. Specific tensile strength modulus of reinforcing

and specific fibers

tensile



MAGAT AND MORRISON

)l

1200


ι

ι

1600

ι

ι

e

C

2000

1

1

2400

—lo

EZEKIEL, H.M., AIR FORCE MATERIALS LABORATORY. T R - 7 0 - 1 0 0 , JANUARY 1971

Figure 8.

Effect of heat treatment temperature on the mechanical properties of carbon fibers at room temperature


146


correlation stage

and

process

between

tensile

incorporates high

stretching

at

( G r a p h i t e HM) tensile been


high

modulus a

aromatic

spinning

process

(glass

transition

structural

without

exceeding as

high

as

upon

200 ° C .

of

the

above

directly

extended

and

a

to is

Tg be

outstanding, temperatures

aromatic

poly-

s o l u t i o n s which

high

no

a

can

temperatures

highly oriented

fibers

high

have

and

at

polymer

c h a i n and

these

of

300°C

creep

jD-oriented

para-

novel

fibers

stability or

crystalline

of

The

or m e l t i n g

shrinkage

extended

characteristics

have

economical

a

crystallinity

perfection.

Rigid

liquid

by

favors alignment

Dimensional no

spinning yield

Because

lower

fibers

a highly rigid prepared

temperature)

500°C.

amides g i v e

from

decomposition

essentially

pitch

a potentially

polyamide which

of

the

fibers. fiber

chains, high

degree

with

as

If and

fibers

somewhat

More r e c e n t l y ,

attention

oriented

heated

treatment

with

is a

polymer

temperature

obtained

to graphite

rigid

pretreatment

carbonization.

2400-2500°C,

strength.

Kevlar®

i n the

are

receiving

route

stretching

strength after

fibers.

crystallinity

further

drawing

is

needed. Let for in

us

now

Kevlar®. two

and

types

Kevlar®

consider

Beyond The

first

creasing

uses

at one-fifth

garments law

such

i n ropes

injury

or

armor o f from

used

to reinforce

boat

hulls

equipment With

including such the

as

modulus p r o p e r t i e s w i t h organic limits organic

fibers; of

are

and

we

The

strong

nine

months instances

prevented

Kevlar®

49

serious

i s now

kayaks,

and

sport

and

golf

extremely

K e v l a r ® , we ask

high

are

reaching

attainable

maximum c o h e s i v e

clubs.

tensile with

o u r s e l v e s what a r e

stiffness

being

structures,

tennis racquets of

29

in-

as

that achievable heretofore

s t r e n g t h and

fibers.

has

and

Kevlar®

In recent

f o r aerospace

canoes

attainment

range w e l l beyond

29

available

in protective

have r e p o r t e d

gunshot.

skis,

and

vests.

is

i s finding

cables which

Kevlar®

resins

end-uses p r o j e c t e d

called

these

weight

as b a l l i s t i c

death

the

Kevlar®

fibers of

and the

enforcement o f f i c e r s

where body

yarns

of reinforcing 49.

as

steel

some o f

tire

the

with

force i n a


a

and

8. MAGAT AND MORRISON

Evolution

polymer

such

rupture

o f C-C b o n d s

ethylene

as p o l y e t h y l e n e would

chains

i n a polymer

a r e packed

t h e C-C d i s s o c i a t i o n

packing

of polyethylene corresponding

would be r e a l i z e d were c o m p l e t e l y flaws for

uniform

not over

parallel

values

and chain

without

polyethylene

a statistically then

discrepancy has

of factors:

(a) c h a i n s a r e

catastrophically Using

simultaneously

principles

values

with

have been force

constants

other

on c r y s t a l

polymers,

calculated f o r

V.

One r e l i e s o f bonds lattice

stressed fibers.

compared

with

attainable with

values

ultimate

polyamides

i n t h e polymer extensions

The spread

based on

chain

VI observed

calculated

and t h e by x-ray

moduli a r e

b y T r e l o a r and

between

t h e o r e t i c a l and than f o r

F o rjD-oriented

strengths.

the theoretical

techniques

observed

i s c o n s i d e r a b l y narrower

tensile

study

Two

on c a l c u l a t i o n s

In Table

values

Fielding-Russell.

Future

breakage.

on other

t h e work o f P r o f . Mark.

used.

which

propagates

polymers has r e c e i v e d c o n s i d e r a b l e

starting

almost

bonds

crack

have been

i n Table

i n the

concentration

few chemical

initial

s u b j e c t o f u l t i m a t e modulus

organic

actual

to stress

leading t o fiber

a s shown

The

This

similar

maximum t e n a c i t y polymers

lead

favored

ruptured.

fila-

smaller

This

and do n o tb r e a k

ends

value

reported

t h e same c r o s s - s e c t i o n , (b) i m p e r f e c t i o n s

structure

on

arranged

t o a strength

o f 11.

a s c r i b e d t o a number perfectly

a maximum

The h i g h e s t

i s 23 g p d c o r r e s p o n d i n g

other.

T h i s maximum

and r e g u l a r l y

maximum b y a f a c t o r

been

t o each

and t h e c r y s t a l

o f the molecules

h i g h l y o r i e n t e d and c r y s t a l l i n e

than

are

energy

i fpacking

to

where a l l p o l y -

one c a l c u l a t e s

or discontinuities.

ments

on

correspond

t o 250 g p d .

only

147

Fibers

parallel

Knowing strength


of Man-Made

limit

aromatic

of stiffness i s

reached. o f Man-Made F i b e r s

Where d o we s t a n d now a c h i e v e d

today?

a s t a t u s which

when n y l o n was i n t r o d u c e d made f i b e r s

range

fibers

spandex

like

from

Man-made

looked

i n 1940.

fibers

P r o p e r t i e s o f man-

low modulus, h i g h

t o high

have

barely possible

modulus, h i g h

elongation tenacity

American Chemical Secioty Library Arthur; Textile Paper 1155 and IGth St.Chemistry N. W.and Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1977.


V

Black

(2)

and

and

Preston

Mark (1973).

(1971).

AROMATIC

^-ORIENTED

Tobolsky

66

POLYAMIDE

(1)

200

2G-T

POLYESTER

165

215

250 g p d

POLYETHYLENE

POLYAMIDE

FOR

THEORETICAL

MAXIMUM T E N A C I T Y VALUES

TABLE

(1)

REF,

FIBERS

(-28)

10

10

23

ACTUAL


(2)

REF,

5

ο

ι

a


Marcel

Loc.

Loc.

(2)

Black,

(3)

(1)

POLYAMIDE

JD-ORIENTED

W.B.

and

Cit.,

Cit.,

p.

p.

Dekker,

35.

21.

I n c . , N.Y.,

J.,

1500

950

m-ORIENTED

AROMATIC

400

CELLULOSE

Preston,

2G-T

POLYESTER

AROMATIC

1780

66

POLYAMIDE

950

2060

POLYETHYLENE

POLYAMIDE

VI

1973, p.

13.

1400

175

200

150

50

430 (3)

Fibers",

REF«

Aromatic

ACTUAL

FIBERS

Wholly

FOR

"High-Modulus

(2)

(2)

(1)

(1)

(1)

(1)

REF.

(IN/GPD)

MODULUS V A L U E S

THEORETICAL

MAXIMUM

TABLE


150


fibers

e x e m p l i f i e d by Kevlar®.

combination The

outlook


f o rcontinued continues

Emphasis w i l l polyamide, still


a very

comfort,

f o rspecialty

fibers

to provide

dye v e r s a t i l i t y and will

continue

o f performance

Developing

and lengthy

one s i n g l e

fibers

limits

man-made f i b e r s .

expensive

fiber

promising.

performance.

search

strating the

and p o l y o l e f i n

goal of identifying

able with

growth and advances i n

t o be h i g h l y

better aesthetics, The

almost any

engineered.

b e t o improve o u r major p o l y e s t e r ,

polyacrylic

ease-of-care the

I n between,

o f properties can be

with

attain-

a new f i b e r i s

undertaking.

Demon-

outstanding property

i s n o t enough;

t o b e s u c c e s s f u l must b e c o s t - c o m p e t i t i v e ,

must halre a g o o d b a l a n c e

o f p r o p e r t i e s and be f r e e o f

any

end-use c o n d i t i o n s .

major n e g a t i v e As

of

fibers

textiles.

entirely

new l e v e l s

been achieved

i n fiber with

science

technology

Kevlar® will

new d e g r e e s

new l i m i t s

beginning

combinations

will

spread

to capitalize

up b y f i b e r

reinforcement.

and g r a p h i t e f i b e r s . new f i b e r s

evolve

With

a new m a t e r i a l

a l l o w i n g d e s i g n e r s and

o f freedom

leading to entirely

of technological feasibility.

Fibers new e n d - u s e s

a l r e a d y have been developed such

as o p t i c a l

s e m i p e r m e a b l e membranes, fibers

of

impact

s t r e n g t h and s t i f f n e s s has

a v a i l a b i l i t y o f these

engineers

their

We a r e j u s t

t h e p o s s i b i l i t i e s opened

A breakthrough the

with

p r o p e r t i e s a r e developed,

beyond on

under

o f the type

used

fibers,

for entirely

hollow

and low d e n s i t y i n "Pneumacel"

fibers

as

pneumatic

cushioning

materials. The great

producers pected of

f u t u r e o f man-made f i b e r s

will

depend

degree on r e s e a r c h accomplishments by and t h e t e x t i l e

breakthroughs,

industry.

prospects

e v o l u t i o n a r y growth t o reach

polyesters,

polyamides,

Short

ina

fiber o f unex-

are f o ra long period the f u l l

polyacrylics,

potential

and

of

polyolefins.


Evolution of Man-Made Fibers

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