THE INDUSTRIAL USES OF"TERYLENE" POLYESTER FIBRE

by D. N. MARVIN.

Presented to a Regional Meeting of the Institution at Huddersfield, 4th October, 1954.

Mr. Marvin

Mr. Marvin was educated at Ilkestone Grammar School and UniversityCollege, Nottingham, where he qualified as an Associate of the Royal Instituteof Chemistry and an Associate of the Textile Institute.

From 1942/1945 he zvas employed in the production of explosives atI.C.I., Limited, Nobel Division, from zvhich he joined the Plastics Division.Since that time he has been intimately concerned with the development of" Terylene" polyester fibre, which is now being manufactured by the" Terylene" Council of I.C.I., Limited.

Mr. Marvin is nozv Assistant Manager of the Technical Service Departmentof this organisation, and is responsible for technical service and developmentof " Terylene " polyester filament yarn.

TERYLENE" polyester fibre Is a product ofBritish research, discovered by Whinfield and

Dickson in the laboratories of the Calico PrintersAssociation between 1939 and 1941. Later, I.G.I.acquired the world rights to the patents, except forthe U.S.A., where a similar fibre is being developedunder the name of " Dacron ". The fibre is derivedfrom the polymer, polyethylene terephthalate, acondensation product of terephthalic acid andethylene glycol, which are obtained by chemicalsynthesis from the products of mineral oil cracking.The fibre, which is melt spun, is manufactured intwo forms, filament yarn and staple fibre.

Staple fibre is in the early stages of development,but evaluation of filament yarn over a wide field ofapplications has been in progress for some considerabletime. It is essentially this product with which we shallmostly concern ourselves this evening, since for themajority of industrial applications so far developed,and in particular in mechanical products, theindications are that it is more appropriate than staple

fibre because of its higher strength and other physicalcharacteristics.

Properties of ** Terylene " Filament YarnCurrently in manufacture are two types of filament

yarn, a medium tenacity, which is more suitable forapparel and household uses, and a high tenacity typeof most use for industrial applications.

Physical PropertiesThe physical properties of the medium and high

tenacity yarns are given in Table I.It will be observed that " Terylene " filament yarns,

and in particular the high tenacity type, possesshigh tensile strength, coupled with a low extensionat break and a high initial modulus of stretch. Alsothe evidence available indicates the abrasion and flexfatigue resistance of " Terylene " to be of high order.The load extension characteristics of " Terylene"are compared with other fibres in Fig. 1, from whichthe higher initial modulus of stretch of " Terylene "will be observed.

231

DeniersTenacity g.p.d. ...Extension at break %Ratio Looptena^ty %

T i tTenacityRatio Knot tenacity 0/

TenacityModulus of elasticity g.p.d.Yield point—Stress g.p.d.

Strain % ...

TABLE I

Medium tenacity

50, 75, 100 & 1504.5 - 5.525- 15

About 90

About 70

About 100About 1.3About 1.5

High tenacity

125 & 2506-7

12.5-7.5About 80

About 70

About 120About 1.4About 0.9

" Terylene" is a hydrophobic fibre and at 65%relative humidity and. 25°G absorbs about 0.4%moisture.

Other fibres which are currently in use in industrialapplications are in the main high tenacity rayon,cotton, wool and to a lesser extent, nylon, and theessential properties of these fibres are compared withthose of "Terylene" in Table II.

Thus, the outstanding characteristics of "Terylene"are very high dry and wet strength, coupled withlow extension at break, high initial modulus ofstretch and low moisture regain.

In industrial applications it is not only the initialphysical properties of the fibre which are ofimportance, but its ability to retain them whenexposed to outside agencies such as heat, sunlight,chemicals, etc. and it is appropriate at this stage toconsider the resistance of " Terylene " to the variousagencies which are of interest in industrialapplications.

Chemical Properties(a) Resistance to acids

" Terylene" possesses an excellent resistance to

mineral and organic acids and especially to hydro-fluoric acid.

(b) Resistance to alkalisAlthough a polyester and, therefore, being subject

to hydrolysis, " Terylene " has nevertheless adequateresistance to alkali for a textile fibre.

(c) Resistance to oxidising and reducing agentsIn its resistance to oxidising and reducing agents

" Terylene " is outstanding.

(d) Resistance to organic solvents" Terylene" shows no loss of strength after

immersion for 24 hours in acetone, chloroform,benzene, trichlorethylene, and carbon tetrachloride.However, at their boiling point, all these solvents,with the exception of carbon tetrachloride, cause" Terylene " yarns and fabrics to shrink unless theyhave previously been heat set. Heat setting will bediscussed in greater detail later in the Paper.

Other PropertiesResistance to Heat

The heat resistance of " Terylene" yarns is out-

TABLE II

Specific gravity

Tensile strength g/den

Extension at break

_ . Wet tensile strengthrsauo

Dry tensile strengthMoisture regain %

Initial modulus of stretchg/den

" Terylene "Filament Yarn

MediumTenacity

1.38

4.5-5.5

25-15

100

0.4

100

Hi3hTenacity

1 38

6-7

12.5-7.5

100

0.4

120

NylonFilament Yarn

MediumTenacity

1.14

4.5-5.5

25-20

85-90

4.2

24

HighTenacity

1.14

6-7

19-15

85 90

4.2

45

TenascoTyre Cord

Rayon

1.52

3.5

10

65

13.0

75

GlassFibre

2.56

6.3-6.9

3-4

81

Nil

307

" Tery-lene 'StapleFibre

1.38

3.5-4.0

40-25

100

0.4

50-55

Cotton

1.52

3.5

7

110 130

8.5

55

Wool

1.32

1.4

38

76-97

16

28

232

7

6

S

i

i

1

§/ft

7If /

— *̂••—«——

iN

x/>«;cos£ __

• — — —

A(• — • — • —

FTATE

Fig. 1. Load extension curves of sometextile fibres.

E X T E N S I O N

standing. Thus, on exposing to air at 150°G for168 hours, they lost only from 15 to 30% of theiroriginal strength while after 1,000 hours at the sametemperature, the loss was only 50%. The behaviourof " Terylene" and other fibres is indicated inFigs. 2 and 3.

It will be seen that " Terylene " is superior in itsheat resistance to all other fibres tested and further-more, its resistance to change in colour is also superiorto that of other fibres.

Tensile Properties at Elevated and DepressedTemperatures

Since " Terylene " is a thermoplastic material itstensile strength varies inversely, and its extensibilityat break directly, with temperature. Fig. 4 indicatesthe tensile strength of yarn tested at temperatures upto 200°G and at 180°C it still retains approximatelyhalf of its original tenacity.

At -40°C, the tenacity of the fibre increases 6%,while its extensibility decreases 30%.

Resistance to Actinic DegradationAs measured by the percentage retention of tensile

strength, " Terylene " is approximately equal to thebest of the natural fibres in its resistance to theaction of full sunlight. Since, weight for weight, ithas a substantially higher initial tensile strength thanthe natural fibres, and, moreover, is much more

resistant to the deleterious action of moisture,chemicals, mildew, etc., it may in practice be foundthat " Terylene" has a longer useful life whenexposed to outdoor weathering.

When " Terylene" is, however, exposed behindglass or " Perspex" as, for example, when used ascurtains, it will be found to have a considerablylonger life than most natural and synthetic fibres.This is due to the fact that the only wavelengthsof sunlight harmfully absorbed by " Terylene " arethose of about 300 - 300 in the ultra-violet region,which are cut off by glass.

Results of exposure tests to full sunlight (weatherexposure) and behind " Perspex" sheet (daylightexposure) on " Terylene" and on other fibres aregiven in Figs. 5 and 6.

Resistance to Rot" Terylene " is extremely resistant to rot, marine

organisms, mildew, bacteria and insects.

Electrical Properties" Terylene" is a good insulant and its main

advantage in electrical applications is that itselectrical and mechanical properties are maintainedat temperatures up to 180°C. The absorption ofmoisture by "Terylene " is, as already stated, small,so that there is little effect on its properties fromthis cause, an important point in electricalapplications.

233

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ft1\ «

1 '

\

\i

V

\

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. 1 l\\

^—___,—.—J

X "TERYLENE"

• NYLON

A "ORLON"

• ACETATE RAYON

• COTTON0 SILK• WOOL

X

43 72 168 336 672 840 1.008

E X P O S U R E T I M E - H O U R S

Fig. 2. The effect of heat on tenacity of " Terylene " and other fibres(exposed at 150°C)

X "TERYLENE"• NYLONA "ORLON"• ACETATE RAYON

T E M P E R A T U R E ° CFig. 3. The effect of heat on tenacity of " Terylene " and other fibres

(exposed for 72 hours at various temperatures).

234

8

7

O 4

AC

IT

Y

Z 4

J

x.,

N

in <o - 40 no 100 I 0 140 160 I' 0 200

T E M P E R A T U R E ' C

Fig. 4. Tenacity of " Terylene " yarn at elevatedtemperatures.

From the foregoing it will be recognised that" Terylene" possesses a unique combination ofchemical and physical properties which are not foundtogether in any other textile fibre. In particular,the high tenacity filament yarn possesses the essentialproperties for providing products of greater potentialfunctional performance and technical merit thanthose currently being manufactured from other fibres.It was because of this potential that, early in thedevelopment of " Terylene", a proportion of thelimited output of the fibre was set aside to determinehow it could best be employed in industry to effecteconomic savings and increased efficiencies.

Before considering the industrial end useapplications which have been or are being developed,it is essential to consider an important stage in theprocessing of " Terylene ", which consists of a processof dimensional stabilisation termed heat setting.

Heat Setting" Terylene " filament yarn may be converted into

the fabrics and cords required for industrialapplications by methods similar to those used forother fibres. However, as manufactured, " Terylene "filament yarn, and, therefore, fabrics and cordedstructures made from it, possess the property ofshrinking or retracting when exposed to elevatedtemperatures; thus "Terylene" yarn in an un-restricted state shrinks by about 7% in boiling water.The higher the temperature to which the yarn orfabric is exposed, the higher the resultant shrinkage,and an approximate linear relationship exists betweenshrinkage and temperature (Fig. 7).

It is clearly necessary, therefore, that " Terylene "fabrics, cords, or other structures which are to beexposed to elevated temperatures in their subsequenthistory, either during fabrication of the end productsuch as a pressure hose or conveyor belt, or duringuse as the end product, as in a filtration or electricalinsulating fabric, must be effectively stabilised inorder that (a) shrinkage of the " Terylene " fabric orcord does not occur with consequent loss of thosephysical properties, namely, high initial modulus ofstretch and low extensibility, which makes "Terylene"emminently suitable for mechanical goods applica-tions, and (b) the end product dimensions may beaccurately defined. Preshrinking of the fabric or

H O U R S O F S U N S H I N E

Fig. 5. Weather tendering of ** Terylene " and other fibres. (Exposed atWelwyn Garden City, 19th May/lst December 1949).

235

250 I. $00

H O U R S OF

Fig. 6. Light tendering of " Terylene " and other fibres. (Exposed atWelwyn Garden City, 23rd June, 1949 /24th May, 1951).

cord prior to use would enable end productdimensions to be accurately defined, but such aprocedure would involve loss of the requisite physicalproperties, and for this reason such a procedure is notacceptable.

Experience in, for example, the manufacture ofconveyor belting, pressure hoses and tyres, has shownthat end product dimensions cannot be accuratelydefined using fabrics and, cords are frequently in-correctly located in the finished belting, hose andtyre, because of yarn shrinkage that occurs duringvulcanisation of the rubber and such, in turn, causesmovement and displacement of the fabric and cords.

The manner in which the physical properties of a" Terylene " cord structure are modified by relaxationat elevated temperatures is reflected in load-extensioncurves (Fig. 8), obtained on a tyre cord ofapproximately 2,000 denier as manufactured fromfilament yarn, and samples of the same cord followingtreatment in air at 125, 150, 175 and 200°G, duringwhich time they were free to relax. The effect ofthe relaxation treatment is to reduce markedly theinitial modulus of stretch and increase the cordextensibility at all loads.

By an appropriate heat setting treatment it ispossible to produce fabrics and corded structureswhich (a) do not shrink significantly on subsequentexposure to elevated temperatures of up to150 - 180°C, and, (b) possess physical propertieswhich do not differ materially from those of anuntreated fabric and cord made from " Terylene "

t

16

14

12

to

t

4

2

• "TER

O "TEI• NY

4

I

C

A

N.ENE" - HIC

N . E N E " - ME

O N

A

•i TENACITY

HUM TENACI

J

/ /

/

Y VBOILING

J

WATER SHRI

/fa7

IKAGE

/V/

y

100 120 140 160 160 200

T E M P E R A T U R E * C

Fig. 7. Shrinkage in hot air of " Terylene " and nylonyarn.

23$

• RELAXED AT 125 CI5O°C

•• I75°C200°C

IO 2 0 0/ 3 O

EXTENSION %

4O 5O

Fig. 8. Load extension curves for " Terylene " filament eord relaxed Ht125°, 150°, 175° and 200°C.

• HEAT SET AT 150 C

I75°C

A » •• •• 200°C

22O°C

O CONTROL

EXTENSION °/o

Fig. 9. Load extension curves for " Terylene " filament cord, heat set at 150°, 175C

200°, 220°C, with 1 % stretch and then relaxed at 150°C. for 20 minutes.237

filament yarn as manufactured (Fig. 9).It is inappropriate here to discuss the heat setting

techniques employed and it is sufficient to state thatequipment for effectively stabilising " Terylene"fabrics and cords is available and in commercialoperation in the textile industry.

The versatility of " Terylene " and the contributionwhich it is already making to industry is reflectedin the applications set out below which have beenmade or are in the course of development. These arefor convenience divided into the various industrieswhich consume the fibre.

A number of important industrial uses have nowbeen established for " Terylene " and it is obviousthat many more remain to be developed. Apart fromeffecting an economic saving on a price/life and/orprice/strength basis, there are possibilities forrevolutionising product and equipment design andfacilitating processes which have not been possiblehitherto with the existing range of commerciallyavailable fibres. Much work, therefore, remains tobe done, arising from which one can foresee" Terylene" making an effective contribution toindustry and the nation's economy.

Industry Applications

I Chemical Filter cloths, acid resistant braids, safety-belts, acid resistant clothing, anode bags.

Contributing Fibre Property

Excellent resistance to acids, bleaches, oxidising agentsand concentrated solutions of salts. High strength,flex and abrasion resistance.

2. Steel Drop stamp belting, filter cloths for gases. Excellent heat resistance, high strength, abrasion andHex resistance.

3. Electrical Insulating sheet, tape and twine, wirelapping, braided covers for flexes, corethreads.

High insulation properties coupled with excellent heatresistance, low moisture absorption, high strength, flexand abrasion resistance.

4 Rubber Tyre cords, vee belts, belting, pressure hose,fire hose, brake hose, fabrics for proofingand coating.

High strength, flex and abrasion resistance, high initialmodulus of stretch and low extensibility, excellentresistance to rot.

5. Maritime Towing strings and hawsers, fishing netsand lines, yachting ropes, sail cloths,whaling ropes, ships' hatch and lifeboatcovers.

High dry and wet strength, high abrasion and flexresistance and low moisture absorption, excellentresistance to marine organisms, good sunlight resistance,excellent resistance to acidic discharge from oil burningships.

6. Textile Spindle tapes and bands, jacquard strings,scouring tapes, heald yarns.

High strength, abrasion and flex resistance, stability tochanges in atmospheric conditions.

7. Miscellaneous Laundry bags, press cloths, calander High strength, abrasion and flex resistance, excellent(a) Laundry clothing. resistance to heat and bleaching agents.

(b) Paper Paper makers' felts. High strength, abrasion and Hex resistance, excellentheat and chemical resistance.

(c) Shoe Sewing threads. High strength and initial modulus of strength, lowextensibility, excellent rot resistance.

(d) Industrial sewing threads of all kinds. High strength and initial modulus of strength, lowextensibility, excellent rot resistance.

(e) Industrial overalls and laboratory coats. High strength, abrasion and flex resistance, excellentchemical resistance.

(0 Laminates.

Canvases and coverings.

High strength.

High strength, abrasion and flex resistance, goodresistance to sunlight, immune to mildew and rot.

238