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Handbookof

TEXTILE FIBRES By" J. CORDON COOK BSc. PhO. CCh€m. FRSC

II. MAN.MADD FIBRES

MERROW PUI}LISI"IINGCO. LTD LS.A. Building,HackworthIndustrialPark, Shildon,Co. Durham,DL4 lLH, England

@ Copyrightby J. GordonCook, 1959,1960,1964,1968,1974,1984,1993

Firstpublished/,959 SecondEdition 1960 Third Edition 1964(November) FourthEdition 1968 Reprinted1974 Fifih Editiott 1984 Reprintedl,993

All rights reserved.No port of thispublicationntay be reproctuced,stored in a retrievalsyslem,or!ronsnlilled, in any lorrn oi by any ,,,eatts,electronic, meclratrit:al, plrctocopying,recordingor atltert'ise,withouttlreprior permissionof tlrc publishus

I S B N 0 9 0 4 0 9 54 0 I

Printed in Great Britain by Redwood Books,Trowbridge,Wiltshire

FOREWORD The manufactureof textilesis one of the olcrestancrmost inrportant industriesof all, Its raw materialsare librcs, and the siuJy of textiles therefore begins with an uudcrstanclirrg of thc fibrci fronr which nrodcrn textiles are rnaclc. - In this book, an outline is given of the history, procluctionand fundam.entalproperties of important tcxtilc nUr.s in ,r" ioaol. The. behaviour of each fibre as it anecb the nature of its fabric rs olscussecl. The book is in two volumes.Volume I deals with the natural fibres on which we dependccrfor our rextilcsuntil cor'pai;ii;;it reccnt times. Volume II is conccrned with .nn-nroi. nLi"r, including rayons ancl other natural poiy,".. fibrcs, and thc lruc synthetic fibres wrrich rravcrnaclesuch iapid progrcss in ,,,o,t.i,i tinres. The book has bee' wrir.tenfor all co.ccrncd with thc tcxtirc trade who require a backgrouncrof information on nt..t t"-ir.r' them in their work. Every eflort has beenmacrcr.oensurc thar thi text is accuratc ancr up-to-d^tc. 'r'hc infornration on 'unn-n.,nJ" f i b r e si s b a s c do n f a c t ss u p p r i c db y t h c ' r i r n u l a c t u r c t r or trr"iibi.s thernselves. In writing this book. I. have bcen given much cncouragcnrent a n d h c l p b y m a n y i n d i v i d u a l sa n d o i g a r r i z a t i o n s- t.- h c nri'rrfalt u r e r so I t h e n r a n - n r a d cf i b r c sn r c n t i o n e ci 'rt h c t c x t r r ^ u " g o i r " - i o "otr,r great .trouble on my bchalf i' providing infor'ratio' in checkingthe text before publication.I woulcllike to o.[no*i"Ae; !h9ir h.elp,with grateful thanks,and also that givc' t" "r" fry tfi. following individualsand organizatiorrs : D. A. Derrett-Smjth.,Esq., B.Sc., F.R.I.C., Linen Industry ResearchAssociation. D_rC. H. Fisher, U.S. Dept. of Agriculture. The Cotton Board, Manchcster. Stanley B. Hunt, Textile Economics Bureau. Pr !t. J. W. Reynolds,I.C.I. Dyestulls Division. N,Ir H. Sagar, I.C.I. Dyestufls Dlvision. I{. L. Parsons,Esq., B.Sc., F.R.I.C., Low ancl Bonar Ltcl. L. G. Noon, ESq.,Wigglesworth ancl Co. Ltd.

FOREWORD Silk and Rayon Users Association' i- C. ni.Union, Esq', International Wool Secretariat' *. R. neath, Esq., and his colleagues;CourtauldsLtd' g.'Lo.A, nsq., il.S.., Cotton Silk ancl Man-Made Fibres ResearchAssociation. K. J. Brookfield, Esq., FibreglassLtd' F. H. Clayton, Esq., Wm. Frost Ltd' J'c'c' Ilurlington Industries Inc.

NOTE ON TI-IE FIFTI-I EDITION The man-ntaclefibre industry ltu, .*pund"d greatly since the fourtlr eclition of. Ilanclbook of Textile Fibres was published. Many new fibres havecome into production in countriestluoughout ihe world, but the emphasishas been largelyon development rather tSan upo' tlle fibre classes, and moclificationof establishecl typcs. cltentical ncw of fibres introductiort of Within ahnost every chelnical class there is now a family of fibres displaying a range of properties and applicationslirnited only by tLe fundamental chemicalstructureof the fibre class.To inciude detailed information about every fibre in production would have meatrt producing a book of unmanageableand uneconomic size. ln this volume, therefore, I have provided backgrounclinformation about eachchemicalclassof fibre, based uruoiiy upon a fibre in current production w1ric6exemplifiesits chemical class.More specific information about individual fibres will be found in a supplementaryvolume. Since the fourth edition was published, production of sonte classesof fibre has been suspended.I have, ltowever, rctained inforrnation about these fibre classes;they are of technicaland historicalinterest, and there is alwaysthe possibility that production of these fibres may restart to meet changingeconomic and technicalcircunrstances. As in previous ectitions,I have been given much valued assistance by iibre manufacturersand textile organisationstlrrouglout the woild. Many individuals have gone to great trouble on n1y behalf by providing information and checking the text before p u b l i c a t i o n .I w o u l c ll i k e t o a c k n o w l e d g et h e i r h e l p w i t h g r a t e f u l thar*s. J.G.C. vl

CONTENTS page MAN.MADD FII}RES

FuNrolrr4rNrrs. oF FrBnBSrnucrune

tx

A. Nalural Polynrer Fibres

L Cu,lur-ose Flnnr,s; R,r,yoNs Viscose Rayon Cupro (Cupramrnoniunr) S n p o n i f i c dC c l l u l o s cE s t c r

"t4

2. Ce,i-lur-ose Esl:n Flnnns CelluloseAcetate (Acetatc) CelluloseTriacctate (friacetatc)

79 80 99

3. Pnorarx Frnnns Casein Fibres Groundnut Protein Fibres Zein Fibres Soya Bean Protcin Fibres Collagen Fibres MiscellaneousProtcin Fibrcs

l5 t7 35 l4l 144 t46 t47

4. MrscrlurNEous NrrrunLr- PolyveR FrnRrs Alginate Fibres Natural Rubbcr Fibres Silicate Fibres Silica Fibres

148 148 153 t't 6 178

B. Syn(hcticFibrcs

9 9 65

t92 t94 209 261

l. Pot-y,ruroe lltnncs Nylon 6.6 Nylon 6 vll

CONTENTS

Nylon I I Nylon 6.10 New Types of Polyamide Fibre 2. Polyr,srr,n Flnnes PoiyethyleneTerephthalateFibres (PET Polyester Fibres) Poly-1, 4-cyclohexylene-dimethylene TerephthalateFibres (PCDT polyester Fibres) Other Types of Polyester Fibre

'

page 292 302 308 328 330 316 388

3. Por-yvlNyr" DEnrvrrrvr Flnnns PolyacrylonitrileFibres Polyvinyl chloride Fibres Polyvinylidenechloride Fibres Polyvinyl alcohol Fibres Polytetrafluoroethylene (and related) Fibres Polyvinylidenedinitrile Fibres PolystyreneFibres

392 393 444 484 493 509 523 s33

4. Polyolerrx FlnRrs PolyethyleneFibres PolypropyleneFibres

536 541 564

5. Polyunsnr,q,ne Frnnes

610

6. Mrscnlr"rNe,ousSyvnrr,nc FlnRrs Glass Fibres Aluminium silicate Fibres Nfetallic Fibres Polyurea Fibres PolycarbonateFibres C a r b o nF i b r e s

639 639 666 678 707 7t4 7t6

INoex

7t9

vlI

INTRODUCTION FUNDAMENTALS

OF FIBRE STITUCTURE

D u r i n g t h e l a s t h a l f - c e n t u r y ,a l l t h e f a r n i l i a r n r a t c r i a l st l r a t t h c world.lras bee. using for triousancrs of ycars huvc co'c un\c -' I

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INTRODUCTI ON

INTROD UCTION

STRETCFIING

I t i s n o w c s t a b l i s h c tchl a t t h c s u r f n c co I a n c x t r r r d c cf li l i r n r c n its t u s u a l l yr n o r e h i g h l y o r i c n t a t c d t h a n t l r e n r n t c r i a l i n s i c l c t h c filarnent.This surface alignmcnt is known as the skin elJccr.lt has an irnportant influenceon thc propcrtiesof the fibrc. Stretching

(e) 'fhc c-xtrusionof fibre-fornring (drawing) Aligntnurl. ant! strctching matcrial'brings ab6ut sorne sliglrt dcgree of orientation o[ the lincar This is nlost pronounccd n'roleculesin the direction o[ the fibre axis. 'skin eflect') (A)' oI thc filanrcrrt(the the outer surface near 'fhe subsequcntstretchirrgor drnwing of the filanretttcontinues thc a l i g r r r n c n to f t h e n r o l c c t r l e st h r o t r g h o u t t l r e . b u l k o f t h c f i l a r n e n t nra'icrial.The crystallinc regions are oricntatcd in thc dircction of the fibre lonc axis. ahd thc nrolcculcsin tlre amorphous region are brouglrt irrto grea-terilignnrent, incrcasing the degree of.crystallinity- of the properties of the llbrc are greatly influenced by tlte nrateiial (B).'fhe 'stretchto-rvhich the lilanrcnts are subjected. amount of

through spinnerets,and the jets haiden as they cool on etnerging 'Terylene',for example,are melt from the spinneret.Nylon and spun. Skin ElTect The extrusion processbrings about sonte orientationof the long moleculesinside the filatnent. This is especiallypronounced on thc outer sttrfaceof thc filanlctrt,whcre the molcctrleshave bccn influencedby the edgesof the spinnerethole.

o r i e n t a t i o n o f t h e l o n g n r o l e c u l e iss c o r n p l e t c cbl y s t r e t c h i n gt h c f i l a m e n t .T h i s h a s t h c c f r e c t o f p u l l i n g t h e I o r r g ' r o r e c t r l c si n t o a l i g n n r e . ta l o n g t h e l o n g i t u d i n a a l . x i so f t h e f i b r c ,s o t h a t t l r c y a r c able to iie alongsideone anotherancldeveloptlrcir cohcsivcforccs. T h e d e g r e eo f o r i e n t a t i o nd e p e n d su p o n t h c a ' l o u ' t o [ s t r e t c h to which the filanrentis subjcctecl,and by controlling thc strctching (or 'drawing') it is possibleto control the tcnsilc propcrtics o f t h c f i l a m e n tt o a h i g h d e g r e e . I * t h e p r o d u c t i o . o f a s y n t h e t i cf i b r c ,w e h a v c c o n t r o lo v e r t l r c c h e r n i c a ln a t u r e o f t h e f i b r e - f o r m i n gs u b s t a n c ca, ' c l h c n c c c a ' p r o d u c e a f i b r c w i t h w c l l - t l c f i r r c dc h c n r i c a l p r o p c r t i c s n n t l b c h a v i o u r .T h i s c o r r t r o lo v c r t h c c h c n r i c a ls t r u c t i r c o f t l r c t i b r c a l s oe n a b l e su s t o c o n t r o l t h e s h a p ea n c lt h e p h y s i c a lb c h a v i o u ro f t h e l o n g t h r e a d - l i k em o l e c u l e st h a t w e r n a k e _ It is reasonableto expcct, for exanrplc,that slcrrrlcr,unifornr r n o l c c u l c sw i l l b e a b l c t o p a c k a l o n g s i c loc n e a n o t h c rn r u c h r n o r c c l l i c i c n t l y t l r a n i r r c g u l a r m o l c c u l c sw i t h n w k w a r d k ' o b s n n d . n g l e s d c s t r o y i n gt h c i r u n i f o l ' r i t y . A b u ' c l l c o f b n n r b o ' c a n c s , f o r e x a n t p l e ,r v i l l p a c k t o g c t h c r n t o r c t i g h t l y t h a . a b u ' d l c o i twigs. . ln 'raking a synthctic Iibrc, thcrefore, wc terrcrto dcsig. our long-chainnrolcculesin such a way that they havc an oppoitunity -group, of packing together with rcasonablecflicicncy. I_arge oi atorns attached to the .sidesof the long moleculcsare generally undcsirable,for exarnple,as they prevent the closc-packingwhicir c o n t r i b u t e ss o g r e a t l y t o f i b r e s t r c n g t h . Crystalline and Antorplrcus Rcgiotrs wherever the threacl-likemolcculesare ablc to pack closcly togcther in a fibrc, thcrc is a tendcncytowarclsan orclercclnrr"ng.rncnt of the atoms with rcspcct to one anotlrcr. 'flrcse tigltpackecl bundles of thread-moleculcsarc, in cflcct, rcgions-oI crystallinity; thcy possessthe rcgular ancl prccisearrangcrncntof a t o n r st h a t i s c l r a r a c t e r i s t iocf a n y c r y s t a l s u c h ^ s s a l t o r c o p p c r sulphate. xxi

INTRODUCTION I NTRODUCTI ON

i n b c t w c c r rt h c s c r c g i o n so f c r y s t a l l i n i t ya r c r c g i o n si n w l r i c l l up with suclr the moleculeshave trot been able to line tltenrselves fibre. of the regions precision.These arc the anrorphous the long we regard fibre-structure o[ conceptiotl this tnodertr In through regionsof orderedcrYs.threacl-liketnolcculesas passing -embedclea in amorphousmaterial talline arrangementwhic'h are The molecuies in the amorphous regions are aligned to sotfle clegree,but have not been lined up with the precisiontltat enables them to pack togetherin a wcll-defiucdcrystallineforrr-r. ^t* ..-*-d

_X-X_X-X_X-X_X-

-x-x-'x-x-x(.1 ^-x-.. 1 ^-x I -ya

(A)

u/n -x-x-x-x(i_" ' ^-x-

(B)

-n-*'1'r-r-*al]*I ')x-""\x I u'xt^ -i-x-x-x(i ^\v "-x/al \ v ,

Cross Litrkitrpatrc!Clmitt Brcncltitrg.T1e productio. o[ loitg molecUle-s during polyrierization of a monorncr X may lake place in such a $u{ as to'fbrrn a linear molecule (A). It may, however, lortn brancnc; nrolecules(B), and tlteseutay evcnttrallylink logetlter to lorm networN structures (C). -'i'fr" fo.ri-iion of brancltestcnclsto reducc the ability of the linea! nrolecules to pnck togcther irr such a way as to form {gsjons^:j crystallinity, and branche::%

'a)

PI{ODUCTJON Rcxclant Synthcsis Thc caprolactanrtrscclirr lrroducittg nylon 6 polytncr is made by one of severalrorttcs,of which thc following are important: (l) CyclolrcxattoneRoutc This is thc route by which caprolactanlis comnrotlly producccl for nylon 6 manufacture(sec pagc263). Cyclohexanonemay be made from bcnzenevia one of several routcs, including the following: (a) Benzeneis chlorinatedto chlorobenzene(l), which is then convertedto phenol (2). Phenol is reducedto cyclohexanol(3), which is oxidized to cyclohexanone(4). (b) Benzene is nitrated to nitrobenzene(5), which is then reclucedto aniline (6). The aniline is then converted to cyclohexanol (7), which is oxidized to cyclohexanone. (c) Benzeneis hydrogenatedto cyclohexane(8), which is then oxidizedto cyclohexanone(9).

bY any of thescloutcs is rcactctl 1'hecyclohcxanonc Produccd n t h c f o r m o [ its sulphltc Nl'l"OI{.1{".SO,), w i t h h y d r o x y l a n r i (ni e oxirne( l0). fornringcyclohcxanonc Cyclohexanotteoxitne is trcatccl with s u l p h u r i c i t c i d , a t t t l run - - - oc-x-{oo-Y-oco-x-coo-y-oco

Today, polyethyleneterephthalatefibres are being made in many countries, and nrodified forms of this fibre are also produced. Other polyestershave been produced and spun into fibres, some of which have beconre oI commercirl inrportance (cf- 'Kodel'). TYPES OT. POLYESTIIRFIBRE In the years since World War lI, polyethylene terephthalatefibres 'Dacron' of tho 'Terylene' and type havc establisheda dominating position in the polyesler fibre lield. Other types of polyester have, however, been spun into fibres with varying degreesof practical succcss. and a few of these have bcconre of conrrnercirl inrportance.

328

rl

-l

.l

.l

(l) PolycthylencTcrcphthalirtcFibrcs (pE.f polycster I;ibrcs). (2) Poly:l^4-Cyclohexylcne-Dirncthylenc fcrcphthalatc Fibrcs (PCDT polyesrer Fibrcs). (3) Othcr Types of polyester Fibre.

--

The lormation of polyesters was studied by Wallace H. Carothersof du Pont during the invesl.igation of polynrerswhich lctl cvcntually to thc discovcry oI nylon. DcvclolrrncntoI tlrc polycsters was overshuclowed,horvever, by the polyarnide research,and it rvasnot until l94l that a valuablepolyesterfibre rvas discovered.ln that year, J. T. Dickson and J. R. Whinfield of the Calico Printcrs' Associationin England made a synthetic fibre frotn polyethylene terephthalateby condensing ethylene glycol rvith terephthalicacicl (see pagc 332). Aftcr thc wnr, developmentof the fibrc was carried out under liccnceby LC.L Lt(|. in the U.K. and by du Pont in the U.S.A., rcsulting in thc fibrcs knorvn rcspcctively as 'Terylene' and 'Dacron'.

r-l rl

The position lrrs now bcen reachcclwhere it is prcfcrablc to consider polyester fibrcs as. specific typcs, i,rscct' rrpon ttrcir chcnrical structurcs. 'I'hc_ ,ifl'crcnc.. il;;";--il*r' irrc Ioo signiticantto permit of rheir beingconsidcreJ;i;pi;;, .polyesrcr, fibres. For the purposcs of the I{andbook, polyester .. fibrcs trc subdividcd into thc followirrg typcs, bascd ,,pon ii,"i, chcnricll structures,and thc abbrcviationsshown nrc irs.,f in rcfcrring to the fibrcs :

NOMI'NCLA.TURI] The first polyesterIibres to be introducedon a conlnlcrciulscalc (i.e. *"." .yrr,.' fr.orii"poty"thyl",,c .'Dacron'_and,Tcrylcnc') terephthalate.This chenrical term was,'of "or.,ir., too cornplcx for everyday use, and rhe fibrcs b;"n,;"-i;;r;n sinrply as 'polyester' fibres. They are still kno*n g.n.r.ily Ly ttris tcrrn todav. 'polycster' is.,howevcr, a specificchcnricalnanre which __llie lcrm rclers to any polynrcr i' which thc rinkagc of snralr 'rolccurcs takes,place. through thc fornra(ion "f ;;;;;r""ps. It rcfcrs

jg1 exalntc,ro.polyerhyten" .,tii"inir. nndcby :::ill",::l!,ethylene glycolwith.

adipicacid,or to polypropylcrrc :onq:n.sr13 terephthalatemadc bv condcnsingp.oiyi.,,. ' glycol"wirh terephthalicaci c r c r r r o v c r cl f l - c c t i v c l y . I r : r b t ' i c st t r a y b c l r : l v c l-) c r i c c t l y s : r t i s f i r c t o r i l y r l t r r i n gl l r r r r r l c r i r r l S , . b t r t t l r c y r c r f o r " r r c c o I l r r ^ r r c - r r fg r l r f r c . r t sr v i i l r r c r r c r r tcr l r rc o r r . c c t t I i r t t r l t i t r g sa t t c l o l l l h c t l s c o f i t r i t a b l c r r r l k ir)g-up tcclrrrirlrrcs. 'l'lttts, l l ' l l l l ' l yg i l r l l r c n t s r r r r c l cf r o n r I r c a v i c r - w , c i g l rl i, l : l ' p g l y c i t c r l ( ) n

369

I t l l l t l l t l l r r t L h h h h h h

I I A N I )A ( J O K O I : I I ] \ I I I , I : I : ] I I I t I ] S

* o o L r r n i f o l t t t f l L h r i c s ,s L t i t i n g si t t t d t r ' c l L t s c r i t r gl lsr c s t l i t l L b l co l l l ) f o r r l r r ' - c l c r n i n g ,r s l l r c ! h a v c i ) o t L r c c nd c s i t l l l c d t o b c r v a s h a b l c ' l r l o s l c l L r r e h l l - p l c n i c dS r r r l l l c l l l sc o t r l r r i r r i r t gI ' l l l ' I o l l c s t c f i i b r c n r L v l , ' c * l s h c d s i l t i s t a c t o r i l y i r t a r r r a c l t i r r co f b y l l a l l ( 1 ,b u t t l r c r r s c o I c x c c s s i v cr v a s l t i n gt c n l p c r l i l l . r r e sI t t a y I c s L t l ti t t < l i s t L t r L t a n c c o f t l i c p l e i l l s ; h a n c l o r t r l i l t l I t t l t c l l i t l c* a s l t i t l g i s g c n c t i r l l y t o b c r c c o n rr r t ct t dc d f o f f l c l l t c d g l t r n l c n t s A l l l r r o p c r l l ' c o n s t i t r c t c d l t l d l j n i s l r c d I ' l r iI ' p o l l ' c s t c r f a b r i c s w i l l p o s s c s s s . r t i s f a c l o r y c l i t l l c n s i o t t l t ls L l b i l i t y t o t h c \ \ ' e s l i i r l g , c l r1 , - c i c a n i n g a n d i r o n i n g c o n r l i t i o t l s t h c , v a l c c x l ) c c l c ( l 1 o c n c o r rDt c r i r l t l s c . ll/ us lti)ig /l !si.\lult I s N o r n r n l I i c l r r i c ld c t e r g c n l s a r c g o o d g r c a s c' l -l lrtnctll o i l c n l u l s i f i e r s , ale illii(leqLralc pfol)crtits. bLrt I)arc l)oor soil-sLtspcnding n l l t y [rc rc-(]cpositcd s o i l a s t l t c r r t i c l c s , s o i l c d hcevily for r.,rrslting on thc fil)rc. Sv llrcLic fiblcs in llrlictlllrr ^lc pronc to thc c l c p o s i r i o no l s o i l f l o t t t s u c l l l v a s l l l i c l L t o r s a, l l d i r b c t l c r r c s t l l t i s o b i l i n c c l L r s i n ge i t h c r s o l p o r a ' b L r i l t ' ( l c t c r g c l l t l, t o t h o f l v l i i c h I t a v c s L r p c r i o rs L l s p c n dnlg p o l v e r s . S o a p i s s r r i t a b l ef o r s o i t $ ' l t c r a l c l s , b t t t i t c l t t t r l o tb c t l s c c la l o l t c i n h a f d w r t c r . l r l h i l r d w x t c r d i s t l i c l s , l l l c a c l c l i t i o rot f 1 rs c' lq t l c s t c r ing ilgcnt \\'ill prcvent lllc depositiotroI a litttc scLltll llc rtsc u i ' t r u i l L ' , l " t " . g " n t - b e s e t l r v a s l r i n gp o r v d c l s o f t l r e t y p c t l s c d f o r \\'liitc collon articlesis llso rccoltlnlcndccl l l : asI t i t r g ' l c t t t l c r a t u r c 'I l c k c l l t ; r s l o w a s p o s s i b l c .a n t l h c $ r s h i n g I c I l ] f c l i r l L l l cs l t o L r l r b jn .tinguishing and thereforeof low llammability (B.S.3l2l). Construction,additives,finishesand the presenceof other fibres have a considerableinfluence on the burnirg characteristicsof any particular fabric or structure. For the purposesof fire insurance,polypropylene fibre is included in tl)e sarrc class as n,ool. 'f herntal Cottductivity Thc following table lists tbe tbermal conductiviticsof polypropylene and other important textile Rbres:

rtore Polypropylene PVC fibre Wool Celluloseacetate Viscose Cottoo

T lrcnnal Cottductivity (relativeto air 1.0) 6.0 6.4 7.3 8.6 I1.0 17.5 590

D: SYNTUETICFIBRES

Polypropylenc has thc lowcstthcrmalconductivityof all conrmercialfibres,and ir this rcspeclis the'warmcst'librcof all. Etfcct of SuDlight

Like polyethylcne, polypropylcnc is attackcd by atmosphcric oxygen,and the reaction is stimulatedby sunlight. Polypropylcne fibre will deteriorateon exposureto light, but it may bc protcctcd c{Ieclivcly by mcans of stabilizcrs. Chemicrl I'ropcrties Acitls. Excellenl resistance, similar to polycthylcuc. Alkalis. Excellent resistance,sinrilar to polycthylenc. General Polypropylcneis inert to a widc rangc of chcnricals.lts rcsistrncc and susccptibiliticsarc similar to thosc of polycthylcnc (scc pngc 554), but its high crystallinity tcnds to nrakc it morc rcsistant thar polyethylcncto those chcnricalsrvhictrdcgradc olclin fibrcs. Eflcct of Org{nic Solvcnh

Excellent resistance,gcucrally similar to polycthylcnc. Thcrc is no known solvent for polypropylenc at room tcmf,craturc. Insccts Polypropylenecannot bc digcstcdby iDscctand rclatcd pcsts,such as white ants, dernrcstidbcetles,silverfishand moth lurvac. polvpropylcne fibre is not liablc to attack unlcssit bccorncsa barricr beyond which the insect olust pass to rcach an objcctivc.ln this case,the insect may cut through the fibre without digcstingit.

Micro-orgnnisms Polypropylene fibre will not support the growth of mildew or fungi. Some micro-organisms, lrowcvcr,rnny grow cvcn on thc very smallamountsof contalninaDts which lnay bc prcscnton thc surfaceof libresor yarnsin usc.Suchgrowth has no cflcct on the strengthof any nraterials nradcfrom polypropylcnc fibrc. Elccltical Propcrlics Polypropylene is an exccllcnt insulaling matcrial, and sincc thc 591

'I NDBOOKOF TEXTILE FIDRES

B:

SYNTHETIC

FIBRES

absorption of nroisturc is so cxtrenrelysmall there is little or no changc in thc elcctrical propcrties at high hunridities - an important point in eleclrical applicalions. Cocllicicntof liriclion Polypropylene has a rclativcly high coeflicient of friction agninstsnrooth surfaces,particularly rnetal or porcelain.Thc cocfiiciclt of friction of yaln againsl, for cxarnple, a yarn guidc dccreaseswith jncreasillg tcnsion. -l'hc coeflicientof friction ngainsta matt guidc, i.e. a guide with a discontinuous surface, is much less tlran against a polished guide, owing to the smaller actual area of contact between tbe yaflr and nratt surface. Coeffcicnt ol Filamenl to Filanent Frictiotl Static friction (avcmge speed 2.5 crn./rrrin.) Dynamic friction (averagespccd 95 cnr./rnin.)

o.32-0.42 0.?9-0.40

Olltcr lropertics I Iandle Polypropylenehas a much less waxy feel than polyethylene,and its fabrics havc a pleasanterhandle.

I'olyptopIlc,rc

Etrvirorurrct al Stress Cracking Polypropylene d o e s n o t s h o w a n y t e n d e n c yt o ' c r a z e ' o r d e v e l o p surfacecracks when sublectedto strcsscsin the presenceof detergents or other substanccs.

continuedcontactwith the sourceof hcat wilt burn with a blucand-yellowflame similar to that of a candlc.A charnctcrislic odour.isgivcnoll wlrenthe burningmalcrialis cxtinguishctl.

Idcntilicatio[ of PolypropJlcrc liil.rrc

When a flamc is brought up to a polypropylcneyarn, lhe fibrcs melt and retracl. A bearl of nrolten polymer is formed, wlrich on

(c) Density Polypropylcne and polyclhylcnc arc thc only tcxlilcfibrcsrvhich arc lighter than watcr, and this is tho basisof onc of thc nlost useful methodsof identification. A tcst sanrpleis cut into lcugthsof { inclr (6 nrur.)or lcss, tclscd irto individunlfibrcsand stirrcd into watcr containinc!r l i t t l c w c t t i o ga g c n t( l g . / l i t r eL i s s p o l N ) . I f t h c s m r l l p i c c c io t fibre float, thcy are almostcerlainlypolycthylcncor polypropylenc.Thesenray be distinguishcd by thcir mclting pointii polypropylcnelics in the region160-170"C., and polyctlrylcnc in tlic regionll0-140"C.,dcpendingon thc typc of polyrncr.

592

593

The following testswill help in the identilicationof polypropylene fibres: (a) Apperu'ance Polypropylene seen through the microscoDeis smooth and featurelcss in appearance. Circular, trilobal and tlclta crossscction filanrentsarc comnronly encountercd. (b) Burning Test

.

l I

' l

r

'

r

r

r-l

'--1

TI NDAOOK OF TEXTTLE FIBRDS

I ' O L Y P I { O P Y L E N EF I B I T E SI N U S I : Gencral Characleris(i(so[ Polypropylcnc Fibrc Goods Initially, polypropylenemonofilamcntsmade their way into applications which had already been pioneeredby polyethylene.They oflered highcr streugth,increasedtoughness,resilience,abrasion resistanccand crecp resistance,and a higher mclting point; thesc properties werc allied to the water-resistance, chemical inertness and other propertiestbat had enabledpolyethyleneto competein a range of applications. Polypropylcne monofilaments on this basis, were soon entrenched in a number of fields where they competed very eflectively with other ljbres; thcse fields included ropes and cordage, fishing nets and twlnes, filter fabrics, protectiveclothing and the like. With the introduction of line-denier multifilament yarns and staple fibre, thc range of poteutial applicationsfor polypropylene libre was extendedinto the generaltextile and apparelfields.This brought them into ccmpctilion with establishednatural and sy[thetic fibres in applicationswhere the shortcomingsof polypropylene fibres often place them at a disadvantage.Despite the many attractivecharacteristicsof polypropylenefibres,less dcsirable properties - such as dyeing difficulties and relatively low melting point - have lended to limit progress. Processitrg Belnviour Polypropylene libres have a filamenl-to-filamentcoeflicient of friction higher than that of any other textile libre. This, in combination with crimp stability and low static charge accumulation, makes for excellent processing characteristics. Polypropylene libres blend easily and ellectivclywith otlrer texlile nbres. Covering Power The lorv specilicgravity of polypropylenefibre gives it a covering power which is, weight for weight, greater than that of any other textile fibre. This has been particularly helpful in the development of polypropylene blankets,upholstery,carpet and apparelfabrics. 'llrcrnnl Insulatiott -fhe thernral insulation characteristicsof a fabric are determincd

s94

B : S Y N , r l lE . I .C l FlnRr,s l a r g c l yb y t l r c a n r o u n Io ( t i r c n t r p p c d i n t h c f : r b r i c . . l . h c llrcrnral conductivity o[ polypropylcnc libic is, lrowctcr, I"*;; it;,;;';i ;i ot othcr tltjrcs,and irr lhis rcspccl polypropylcnc is lhc ,wanlcst, Oreln commcrcial usgCrease Rcsistance The ability of a tcxtilc labric to rcsist crcirsc Iormatiorr durirrt use is inlluenced by the physical naturc of lhc nbrc itsclf. Irl th; casc of polypropylcnc fibrc, this charactcrislic varics with thc molccular weight of thc polyncr, and with thc conditions o[ sp-inning and dra.,ving. Polypropylcnc yarns arc protlucccl iu which the crease resisl.ingpropcrtics are at optinrunl valuc for applications where this is imDortant. In gcneral, the crease-resistinccof polypropylcnc Jibrcs is of the same order as that of wool. Uniike wobi, howcv"r, poly_ propylene fibre docs not losc its high crcase-rcsistancc whcn wct. Shrinkage By.controlling the condilions of proccssing,lhc shrinkngcchirrac_ tcristicsof polypropyleneyarns may be varicd ovcr a considcrablc range, Shrinkage of polypropylene yarns is quitc low under thc tusualconditions of Iabric scouringand dyeing. Speciolcarc must be .taken, however, whcn high-lenrpcraturchnislting treatmcnts sucn as rcsln curing ilrc uscd. Shrinkagcmay bc lrigh ilt clcvatcd lemperatures. This shrinkagc causedby high tcmpcraturcsis not progrcssivc, and polypropylcnc fabrics nray be hcat-sct. In cornnron witlr other -syntbetic fibres, hcat-treatedpolypropylcnc yarns which have been allowed to shrink and Ueconicsrribitizc _ NHCONH- POT_ NHCONH- RI - NHCONH- POt- NHCONH_ Chain extension with glycol or diamine.

This final chain extension stage may be carried out also by addition of water to the isocyanate-terminatedprepolymer, instead of a glycol or a diamine. Water may be added, for example, in quantity sumcient to react with a proportion of the terminal isocyanate groups, forming pre-polymer molecules with an isocyanate group on one end and an amine group on the other end (l). When this polymer is heated,the amine and the isocyanate groups react to bring about firrther polymerization and crosslinking of the molecules (2). ocN - Pot- Nco + Hro $ocN

- Pot - NHrn co,

g! ocN - Pol- NHcoNH- Po1-NHz oct.r-Pol-NH, t oCN- Por- NH, Chain extension with \rater

Spinniug The techniqueusedin spinningspandcxfibresdependsupon thc type of polymerthat is spun.Somesegmented polyurethancs, for example, are essentiallylinear molecules,and are solublc in solvents.Other segnrented polyurethancs may be branchc