·
. ~: ;-.. :
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r:-'
f
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\
H,'I'''''''''' It,,,,, Ih.. ./,,,,,,,,,/ ..! Sd,.",i!;,. ,( /"'/flJ/,./"/II".\(·"",,,,. 1'17K Vol. .11 N(I. 10 I'll. ~IJ· ~IK
Aromatic Polyamide Fibres
II. SIVA RJ\1\11 1t!'!>llY. (jAN(jA RAJ)HAKRISHNAN. K.T . .JOSEPH &. 1\'1. SANTA""A
.f.' . .
Polymer Division. Ccntral Lcather Rescnrch Institute. Mndrns 600 02()
~
TilE aromatic polynlllide tihr.:s arc widely uscd today.
The propcrties like good heat resistance. tensile
strength and impact qrength make thel11 suitable ror
application in nelds like aerospace and marinl' industry. The dcvel(lpmcnl or hi[!h temperature and
11:II11c n:sistant tihr('~ has 1'''11(' I1ninl" alnn!! Iwo lil1c"
(i) by modirying th~ ordinary' libres by posttreatment to make them name resistant, and
(ii) by preparing special lyre or fihres which arc
inherently resi.stant to high lcmperature and
name.
The aronlatic p(llyamide tibn:, belong to the second categ"ry. They possess
superior mechanical 1'1 "p('rtics and thercfnre.
can replace metal allnys in aer.)spaee industry.
A wide range of polymer compositions has been 'developed with high strength and flame resistant properties
and· most of these materials rail within thc CI<ISS or
polymers knowll as "ar:llnids".
This revicw deals mainly with those polymers whidl
arc inherently namc resistant and havc a high contcnt
or aromatic groups.
Synthesis
The aromatic rnlyamidcs arc produced by l11ell
polycondensatioll, solution polycondcnsation or inter- .
racial polycondensation. In gencral. react:lI11s (diamincs and diacids/chlorides) arc blended in cquimolar
proportions to achicve high nlOicclilar weight prnduds. When onc or the reactants is used in cx..:ess.
the lower molecular wcight species are al>o obtained.
Me" l'o/ycondel1Salioll ..-Aliphatic pnlyal11idcs.onc
of thc most important classes ·of condcnsation plllymel's. have been prepared by this. proccss. In thc case
or aromatic components, this method has scveral
drawbacks. such as (i) low reactivity or diamine and
(ii) decomposition of the reaction mixture. i'vlany
513
quantitative,yiclds withinhercnt viscosity 0'6-2'5, II'
thesc polar solvents arc wlltcr-ll1i~cible or at least pilrtially water lIIiscible, thckss basic acid acceptors :II'C
I
prcfcrrcd for minimizing the acid chloridc hydrolysi.~.
. I
. ,',
:r-- ~.' 'c."
Evell hicarhonalcs Gill he used for hydrolysis (,1.'(':III't'
,
i
Ihc a""lIlali,: .riamill('s art' Vl'l'" weak il .. ,c< Th ... 1I'.l'
(,I' sol.velils \\'ilh apprct:iahle "::11,:1' IIliscihililY :1(11'(';1/"
b l(, I··, Route for ,ll'Of11jlljc pol)'alnidc prodUl'Iiu"
. the nriL!inul c/clinilil.lll of Ihl' illlnt.., he t'l'ntrary to
'
J •
•
.' .. facial polycondcflsati~1J melhud and to ,11.: pre~ed.illg
of lhese poi Yll1ei's have h(gh mel'ting I)oint~ ;,;ldthere- COnll11e.nts nn the qetl'llllcll(al effects (If posse IllISClblforc, they CHonol hc melted \\'ithout decomposition: lily.' The illlprovcmei1(r~ilIi7l'd by ;~c IISC of \\'akrhellce, this method is generally not suitahle for prc- miscihle solvelll~ i!oes,'!Hl!'arise frdni Ihe potelltial
I'arillg Ihi, class (,r polymers.
miscibililY or Ihe 'phasl~s. Thc advanla,l!c ,'('llleS 1'''''111
I/lff'ljllcial 1'(}/J'II1,'ri;:atiolll-2~ _.. , The aromatic dithe II~?' of polar solvenls which :ll'e bctter sol\'l'nt~
anlinc~ are, gellcr,lIly, 'ill:rclive and hCIlt:C, ill inlcrf:lcial or sW':iling agcnls for many cOlldcltsalioll polyll\n~
polymerization the condcnsation is ell'ccleu by using lhan :1I:e (hc hydrocarbons or chlorinated ,hydrocarllIorc rcactivc diacid chloridcs. This mclitOd involves nons IIs'ed previously, In lhcse solvents, Ihe rcaction
dissolvillg or Ihe dial.ilinc (J) in Watcr with 1111 acid ralc is enhanced because or nlC increased polarity or
acccplr>r (NazCO J " ' NaOH) and thc diacid chloride thc lIIedillI11 2.1- 25, The polymcrizalion is hclieyed to
(2) in an iml1liscible solvcnt. The cxtcnt 10 which
takc place near Ihe inter/lice of a lwo-phasc liquid
Ihe rcacl ion proceeds depcnds on various factors, svstem:
.
Somc of Ihese arc asfollowi;:
- SO/lIliillr/llil)'lill!riwfioI/26-:56 __ In this mClhod, thc
/?('w'ficll/ (·/I/I"il;;II/.\' ._.- For high yield thc temperarasl reacting intermediates arc hrought logdher in an
inl'rl liquid mcdiulll and the acidic byproducts ir any.
IlIle is kCf'1 at SolWe" with high spccd slirring, .
1'111'ill' "f' /'('IIc/,/11I.\· "- The n:actanl~ :Ire carclully
arc removed by mcans of basic_addili\cs (acid-an:l'ppurilled: tllC diamine is plIrilied by fractional uislilla- tors), Thc diamille is taken in a suitablc solycnt and
tioll and vacuum sublimation and thc acid chloride mixed rapidly with (he acid chloride in the same solis di.~tilled undcr high vacuum. Thc optimum mole vent. Tertiaryamine is cmploycd as an acid acceptor.
ratil) of diamil\c to acid chloride has bcen found 10 Kwolek ('f 01,26 suggesled anolher variation in the
be in Ihe range 0'9-0'93, .
,
solution polycondensation method, applicable ((I aro(1'1'6 of .Wh:C'lIt-II'lIfCr i/lIt'lfil('t' - The prcparallOn 'mutie diamincsand othcr wcukly basie inlcrmcdiates.
or aromatic polyalilide was reporlc'IDby Russian wor- in which a weakly basic organic liquid scrvcs both as
kers. Bea l11:1n cf al. D prepared. poIY(III-phenylcne- solvcnt medium ror polymcrization and as an acid
phlhalanlide) IIsin£:! he07,ene-:l('l'tpne-watcr syslcm acceptor. Examplcs or Ihese mcdia arc Iclrarnelhylwith illherelll viscosity 0'7.1 (74 ~;; yield). 1,:II<:r, u rc:. 29, Iclmhydrorur:lnJI, dilllelhyl:lcCI:llllidc 29 ,lu.l,I,.",
Morgan ('( 111,14 prcpal;etl)polyamides usingdid,loroN-llIcthylpyrrolidone2R,30,32-J$ und hcxamcthyJphos.
mclhane-watci' mixlurc. Katz lS rcporled Ihc pre- phor:tmidc32.J4,J5.
Thcsc alllidcs arc all much
paralion or polyorlhophthalilinide or his(4-amino-3- weakcr hascs27 thal,.,primary aromatic diamines, but
1lI('lhylphl'llyl) melhane in chlorolill'lll-w:Jler wilh an hv using all. excess 'or :In 11l1lidc, the polyrncrizlltio/1
inherenl "iscosily 0'.15 (X9";; yield). The It,\\, in- :i~-hrollghl 10 l'ompietionwilhoul any loss or diamillc
hcrcnt viscosity ill. this case is mosl pr(lilably dill' to as an inactivc hydrochloride. An illlpoJ:lant feature
chain lermination through imide rormation and not. ior Ihis type or polycoildensatiQIt is(.high yicldwith
due 10 It"" polymer-solvent interaction or the low modcrately rast .reaction. HO\ye~cr, tl}t;, in1Po~t3nl.
reacl ion ra Ie. Sokolov cf' al.l 6- IR preparcd a number prerequisilcs are: (i) ildequa'le alilOunts of'the~"sol\:CTlt
of wholly aromatic polyamides under dilferent con- and Ihe acid acceplor, (ii) purilY of the solvenl'1Ind..,
<filiolls. II \\'as round Ihat produ,·ts or comparatively the rl'aclants, (iii) propcrdegrcc .. fmixing and slirriilg,
hi!!h IlH,kcIII"r 'H'i!!hts \\'l'I'C obtaillcd ill dilute solll- (i,·) I":,lpl'r sclection lIlld Ct'nlrol or ~ol\'cnr. and
ti,;,,<; ill p('"r sl,l"e~ts and in aqueous acidic phases. (v) dUr:Jlion of reaction.
Fcdotova c{ 111.19-21 attempted thc preparalion of
aromntic polyamides using benzene and CCI 4 as sol- Mechanism of Formation
vents with dilute solutions in 0'005-0'05 M range.
A succcssful polymerization in thc presence oraminc
The rcduced specific viscositics wcrc <0·5 for J 6 acceptor is shown in Fig, 2,
,
nul of 20 polymerizations; t!lese; ..arc comparable 10
Ihosc obtained in high teli1l)ej·1)~ure. reacti(lns~bclwce.n
di:lIlIincs alld acid chlorides:',' 'Pc)ly(scbacyl" benZIdine) was produced with lhl' highc~t solution \~iscosity
in :Ill acid l11'edilll11, whercns the other polymcrs re- '.
quin~d 2-1·) l110les or KOI-I/nwle of dial11ille.
'c
The "",\, consistcnll" successrul t"'(I-phase 1ll1'1h"d
I'llI' I'rl'p;lI:i".!~ \\'h"".,, :in'I1I:1lic polyalllides is 1I1:1I ....(,r
I lill "1 (fl.~'. III which Ihe I'"Iy"n"de"";lli<'1I f'nh'c'dur,'
. ".
was Jl1,'dified by using incrt polar organic lil(ui,b. ,uch
as cYciohexanone, tetramethylenc sulphollcs and Fig . .2 - (jl~nC'rallllc'chal1iSI1l r",,' pt.\lyamidc Itll-l1lati()11 rku+>
tclrahydroruran, Polyamides were produced ill nearly
k I> krCaC'i\Il' mh in sl
.. "
51,)
,-$
,-
.A
'1-'
vent used, III1Y or the following coa1!uluting baths is
solvents could bqlrepared. This has not been possible in lhe cllse or polyamides containing only pheny- cmployed.
<I) 'Triethylamine and ucid acceptor (Nn 2 CO J or
lene units. In the c~se or-het~rocyclic Itmide copoly·'1'IaOH)~low.20°C62
.
mers, the helerocyelic illell~ct replaccs "tWO 'amide
. (2) '35-4 parts trietliylamine an~ 1000 paris telmlinkages and II phen~lelle unil of the ord~red copoly. '{lydr9furitl) ITIiF) at 5°(:62 ,
. amld!:s ,Ill! shown in fig. S, The effect of the 6-memmll3
p!,rts ·fi20 ~na 7 plJrts Me~')
.
bc;rec\ heterocyclics in 8ti~n1atic: p'olyan,jdes has been , .• ,(4}:.\,iH ~o.' aqL,<;J I1~W~;l\nd at 2\"~~
.
. !it·de ~~uilicu,.
" .1.
'.', \ •.
(5};~
%
ilq
~icr*Ct~Q~64
.
,~C
.. ..
. . .:~
(6):.TetramethYlut~' and 6·5~~ tlCI at 140·CJ5
(7».43 wl%.~"CI2 ...t 60·C28_ .:.
~
(8) Aq KCf2: (.'. '."
(9.)
(J()
Fig. 5 - Mode or rcplaccment or amide links by
heterocyclic unit
\i
DipftJPylcme glycol bath at 6~"CI2
91 parts hempa (solvents optionally contains
metal halide) and 5 % LiC112.
Rcports arc available on the usc of surfactanl!; in
cOllgullition huths whcre they help In drawing or fibres
at 85" in wlltet65 and bring along partial orientation
of the fibres. The rate of spinning also has an effeci
on orientation and hence on the mec~anical.p~()pertie~-
(<I) In case of polyamides derived rrom I,-isomcrs of
acid chloride and diamine, the para phcnylene contcnt
decides thc solubility as well as rigidity and modulus,
nut processability is improved hy thc incorporation
or the mela components. Cerlain copolymer com- Properties and Uses
'..
.
with requisite solvents have been devc-.
Numerous reports are available 'on lhcrprepiuatioil
loped ll - 56 .
.
. of a variety or polyamides which have been evaluated
. in fibre form under experimental or developmental
Prclllirnlioll or Fihres
progr:unmes'4-56. Commercial exploitation hilS been
Aromatic fibres have bec:n obtained both by wet 57 possible with two types or fibres: 'Nomex', poly(mand d ry 58 spinning procedures. Good quality fibres, phenyleneisophthalamide) and 'Kevlar', poly(p-phenyarc obtaincd rrom anisotropic solutions as obscrved Jeneterephthalamide), Both these fibres have an .exby the appeari,\Jlce of a maximum in the solution cellent balance of physical and chemical properties
I viscosity-polyrfjer) concentration
Up to and have wide utility in industrial and inilitaryapplithe maximuill solution viscosity, llii:systCQl behaves as cations, The production of Kcvlar hilS been growing
a normal isotropic onc, But further inci-eltsc in poly- steadily. There nre three differcnt types or Kevlar,
mer concentration lQ.wers the solution viscosity.. viz, Kevlar, Kevlar 29 and Kevlar 49; the last one is
This is duc to the transrormation rrom isotropic t6 of high modulus type obtained with maximum ·hcat
parti.tlly anisntropic lil1uid crystul state. where the· treatment lind orientation. On weight basis. the tcnp"lymer molecule exists in Ihe fullv ellienlied form'; sile strength of Kcvlnr is almostlwice that of glass und
this helps in obtaining fibres in
oriented state. five times
of a'steel wire. lis lensile modulus is
The 'parameters defining the production or:n~ aniso-",\50~~ grcat~r than ~h~t.~.£.steel wire.
.,
tropIC dope are solvent type, polymcr molecular weight .• Aromattc polyai11lde ·fibres have been churaeteflzed
ami solution Icmpernture('o..
hy X-ray studies. Nomex is shown to, have a tric1inic
cell with a, 5·27: b, 5,25: and! c. Jl'3A (fibrosis),
'1..
111·5: ~, 111-4; and 'Y. flO" with erystnl densily
Soh'rnls IIsrc1 ror Ihe Preparation of Silinning Dope
1.47 g!1ll1. The amidc I'roll)l and nronmlic ring are
II ighly polar solvents likc dimclhylacelamidc 1101 t;llpl:lIlar, hcc:luse thc rill!! hydrogell interferes'
(1)1\1 AC). hl'xalllcthylphosphc'nllI1ick. N-IlIC:thyl \lyrrn - with h\'I1""",'n hond formalin". Thi, ~tl'ril' hilldram't'
lidonl' and dimclhvl fonnamidt' ,,·ith I ;('1 nr t. ';t( '1,
is "n', ('11111;' h~' h~'dro!,en hctl"lill!, .. f Ihe :lIlIi(t.: !!r(lul"
:lh' u, ... d. In the l'a:,c of poly (II/_I'hcny'lclll'i'(lphihal a·.
pel pelldi~td:1I 10 the aroliwlic rill/!. III the ea~e ,.. I
mille), direct spinning is possihle by carrying (lui meta orientcd polyamides, the molecules in thc crystal
polymerization in suitable solvenls\(·-J3. These arc lIrc contracled byl 0 per monomeric unit fr,om lhc
weI spun at rO\)111 temperature into walel 2J •4 9,50 or fully extcnded conformation and hence possess lower
dilul.: II~SO.I coagulants. The fihrcs arc then wa~hcd
tensile o;trenglh and grelltcr c\c'ngatinn compared to
,thmnughly and dried, The major breakthriilll.!I,I~:ame thc .1'(/1'(/ isomers (Table I). From the moisture regain
with the applit:alion of Ihe dry'jet wet spinniil1! :pro- datfl, the crystallinity of Nome:\; is found 10 be 47";,.
IT''~ whcre Ihe spinneret is kcpt at ahoul I em' :lb.'H'
The melt ill!! poinls <'f ar<,malic 1'01yalllidcs arc
thc c.':Il!ula!iclil h:lIh. The a<i\"anta1!e< cd' drY jet \\l't
dill:dh rel:lI.:d 10 the ('ri,'l1tali,'n lo/"Ift". ",,'1(/ Ill"
Sl'illllill;; arc: (11 the' ,pinning d"l'~ C'III bl' \"1'1;'1;11 high 1.111/".1).' 011 comparing the fllily
nnl'lIlnl Ill'ly·
tctllperatun:s and hence. higher polymcr t;lll\U:II- mer, it is observed. that the melting point js higher by.
tratlOns can be obtained; (2) the shear stretch applied
IOO.C in the latter, whereas '0/,,110 substitution lower:;
to the dope durin!!: extension increases orientation and trle melling point .. Similarly. incorporation of naphh.cIlcc el!minales -the expensive post-heat treatmcnt. thalenC' or hiphenylcne rings incrcases Ihe Illelting
1 he Icn~IIc, slrcn!!th or the as-spun librcs depends Oil
point. In :!lllhcSI) cases, Ihe I;lns~ Ir:tn:;ili('ll IClllperaIhe type nf the: Sl,IWIII and decreases in, 11ll' of"(\crr.l:
lure is :!I,(\ve 2~O' C. Thi~ ha" a praclical signilic;lIll"c
1)1\.11\(':-- \)1\~SO :.:' 1)1\'117. ncp~nding nil the ~"I-
po~itions
:i
I
'I
I
~Jation59.
p"rti;~lIy
(7"'1..
~f
~hat
1'''''''
516
:, :
.
i
:1; !~~0]~:~:\i;~;;~i;·fJ~:.~~~i~~~"1~
.. ; .
'I
SIVA RAMI REDDY ('/,,/,: AROMATIC l'OlYAI\'lHlE Flnl~r:S
i
For giving a suit.able explanalion for Ihe polycondcnsalion system. it is necessary that. Ihe amide-forming
rcactions meet the following rcquircments:
(I) The acylation rate antiproton amnity of Ihe
amine groups !ire presumed to be proportil'"al
to their base strcncths.
(2) Amine hytirochlOl;des or prtltonatcd :tlllines
arc not ucylatcd by add chlorides.
(3) The ratc of reaction hctwecn add chloridc and
amine is high, but the rate of removal of the
portion or hydrogen chloride from the protonat.ed al11ine in the presence or base is still
higher. During polymerization, frce dialllinc
is the acid acceptor as long as it is availahle and
it becomes weakly basic soluble monohydrochloride. Alternatively, an effective acid accep, tor, such as tertiary amine is added, so that Ihe
, p6ly~erization proceeds to give high conversion.:','"", '
.,; ';,:.
.. ~ . .
Errect odl'~~~t~nts,
The polymerization 'is highly sensitive to the reactant
concentrations and, the volume ,ratio of the, solutions,
Thepreferr~d :coilcentration railgeis 1-8 g reactants!
,100 ml solvent.o:1LO\ver concentrations are unecono(micill:,anfj~t~()ducelargeal11ounts or, solvent impllriUe~,> H1Shfl.r;.c::oncentl'ntiol1$ inny YIeld lI'\stirl'llble
tllassesancl:the:hcat' of the reaction is difficult (0 controIWhcnJ,l1e, reactants 'arc mixed rapidly.,
Elfec~'or~~fv~iPi::;;;;:' :::"; ~I::" ,'",~;"
",'TI.ui:soly~~,(,pe~r~r~ss~~eral functi~n~: (i)dissolv~s
Sevcral useful polyamidt's have oeenl'rcparcd based
on Ihe ahove p()s~ibililies and Iheir propcrtie, hal'c
been evaluated in lin a tll-Ill pt to establish a' rciatillllship betwccn the structures and properties,
(I) When the skeleton is connectcd ()Illv wilh th('
hen7.ene nucleus, partl position gives ptll);mers lI'ilh
higher decomposition lempcraIII rl'S ;lIld Ihl"l'll1;lI
stabililies thall those oblaillcd through 1111'1/1_ ,lIld
orll/O-suhslitutions. The melting points of ar(llll:!tic
polyamides arc related directly to the oricnlalioll (i.e.
orIlla, melll or para) of the arylcne units in thc polyIllcr repeating ullit. For e)(amplc, thc replacement of
allllll'la groups by pom groups raises the Illelling point
by 100°C. In g~neral, incorporation of sYlllll1etrical
naphthalene units and 4.4'-biphenylenc unit in place or
p-phenylene unit produces no significant change in thc
melting point of the polymer.J.
(2) The introduction of simple chains like -CH2
groups bctween benzene rings in the diamine or substitution in the anlide link increases the solubility. In
the case of aliphi\tic-aromatic polyamidcs, N-l1Iethyl
substitution results in marked lowcring cir the melting
points." For example, when half of the amide linkages
of the," poly-isophthalamidcof p-phenylene-N,N'bisamino benzamide are replaced by N-mcthyl substituted' groups, the melting point is lowered by 195°C.
Such n decl'casc in the I11l:lting point in the wholly
aromatic polyamides seems to be aUriOl/II/hie as(I11uch
(0 the,disruption of orderly packing a~' to rcduction
',~~~d~r~e~e~~~~i~~~es~rH;e:~s~~~!~~ r~I~1~~~t7~~
polyamide becau@or the fllct that~poly(2,5-diincthyl'
the, IId~r~epH~.tes,ari.dhelps,intheir mixing and con- piperazine t~erephthalaminc), .in 'which 'there' is no
,~tact" (II) ,:d~~sol,ves;or,:, swells the grOWing polymer. hydrogen o6nding, has' Illclting point 3~O°C. The
1~hereby"t9~;:reaction)s, maintained, (iii) Carries the" t~~ducti0'1) of he!ero~ycli~~:Aljke p,ipcrazine. rin~s"
acida~ceptor andlllayaffect.the renloval of byproduct O';JI~ and p-phenyle!ledloxyrJrnkages mto the dral1l.ne
salt':(lv)·m,ay..alfe~t,the' reaction rate by polarity, and' pro,qllces polyaniidcs with' fairly high molecular
(v) absorbs; the heat of reactio~The selection of the weights, This substitution improves thc solubility
organic 'solvent --for - interfacial polycondensation of the amide polymers in' various solvcnts. The
reactions is recogniied as be,iog'related (0 the degrctCvaribiJ§ groupslowers.th~ melting 'point of polyal1lidcs
of polymerizatibri 41 ,42.:, ,',
"
,
' as shown in Fig. 4, ' ,
"
"
"
' "~,' , eJ), ' " fr;-:~;::":
(3)Sl,nce tractahility is II' probieiil in thefic:Jd or
Err~ft",!r S~.I!~t?,r,~ o~cP:!)lymerProperlies
,ther,rn~st~,'* ,who"Yll"~lllatic: ~oly~midc,., both 5MallY r~9(Jlfi~{i~i1s,;:havc bceoproposed in the and ,6:-melllbel:ed aronia(.? 'Ic(crocy~hc \lnlt, such as .1.; .
«Skelet,9n st~':J,'ctute~; q(.J?olylullidcs: with the' object of oXildt.a~.ole,. thrazo'e.'pyrrdll1~ arc; mc(~rpora.ted. I,Jl.
StLtdY'llg the, relatlOnslup between the structurc and ract,.t was found that by the IIlcorporatron 01 certaIn
. ":"". tli~ -j'iroperties' o'r.~;the Ipolynier and'succeedcd in the5~membered aromatic, heterot;yclics; polyamidcs hav,j
,~)!eparpti?,n'or highmol~cula,r weight arol.nutic poly- ing m~l(ing p()ints above ~.o0·C,and sgluble in organic
<1~lI~~S wlthexc<;lIe'.l~ properties, such ~s 11Igh thcrlll~\1 .
r ' .... ,'"
"
s~\b'}lt~ a~~.'soIU. bl.llty, The prope. rtles of aromatIc
_L_ OCHN~~'N"'CO~'"
polya~ldes,se~l11".to ~epend primarily on the rigidity
L
0(. the pelymerf,chamjbackbone, 'The 'fundalllenial .
',
."
:s~eleto\n struS:tut~, ar9matic. polymcrs is shown in
Fig. 3 - Skclclol1 structure or aromatic pqlyamidc
,. F!~: 3.1 ConSI~.~rlpg the ?ifferent typ.es of groups subStltu(fd for l\,t'lt'IS p.osslqle (o,dass.fy types of polymers'as foIl0\\'5':'
"'.,,,"
, ... '\
.,
C)
, J.
9'c
,',)
. (a).
~[~6CfIN~Ar~NH.Cb-]n
Th~.d1.~$lri:~ coirij)6mint can b~dlamin()benzene,
<Iral11rnod.ph~nylme,tha~e~ diphenylene sti!b~ne or
d.en an ether,;,or:sulphlde group or sulphoxldegroup
cont~ining. d~lllinol?,enzerte7; and (b) the acid/acid
-chlorrde COinponel~t can be varied over a wide rangemomatic, aliphatic or heterocyeli<;.
-C)-(HrG->-<2(H~CH{)
)
{}.> C")->.(c}··>·
Fig. 4 - Variou~ groups arranged in dc~rcasing order or .heir
ability 10 reduce Ihe mclling poinl or (l~lyun'ilk
515
'j "
,......:'ii!'(?Jtr:;:}~·0i''.;f;~;~;(ii~,~~~~c'f~(nlF5:~:Ji'':?::;~'~J;¥~;~1~~f~p:~"~f;0~;':'!ti'!0~f!)~~fff':\::~~~:;·.· "
'l.l,
SIVA RAMI REDDY
~
TMILE I -
..
'fJ
"'~!
Ii
I,
!~-,
J
Modulus
N/lex"
35J
1850
19411
25411' '
Nomex
Kevlar
Kevlar 29
Kcvl~r 49
(1/. : AROMATIC
or Nmux ANI) KF.VI.AII
Tenaci.y
mN/lex
Fihrc
~.;
PRf)PF.RTIE~
cf
Ex(cnsit'l1 at
break,
6·2
4t ·9
35
4~'4
J·4
X9·5
2·t!
j'/
In
4
----------':.:..:."---_ ..
TADLE 2- PRQPERTI['~ or PPT FmRE s4
Initial
Hea. Ircalmen'
Tcrnp .... C
"
Modlllu~
TcnacilY
mN/lcx
Extension
618
9·1
-12117
1·(;
III
/n
N/tcx
,.j
~f
.II
f
~i
As spun
15·3
5rnrC
7X·4
.fl
.
I.
.fl"
t~
~!
r
~l
'\,I
.1.;
FIBRES
formers. In view of its high fle.mral strength. Ke\ 1:1'1'
is lIsed in the manufacturc of holting ror high pressure
hydraulic systems and material handling . equipment.
In comparison to sled and viscose rayon. Kevlar reinror.ced radial tyres give longer lhread lire for thc lens!.
we.ght. Keviar 29 is uscd in slings and strappings.
It can be wovcn alone or iogether with other librcs'
10 produce induslrial fibres. balloon fabrics, cllakd
Iilt-fics, parachule fabrics. ctc. A Kcdar plllvcsl('r
fibrc sail cloth is IIsed in racing yachls. Thl'se f;",rics
are used for Ihe production or laminales and com·
posites, which are used in interior and extcrior paris
in aircrafts 67 . Thesc polyamide rahrie laminates wilh
epoxy polyeSll'r resin comp()siti()II~; illl:rcasc the still'ness or boat hu·lIs, paddles .lInd spars alid are' 50~;,
stiffer . than typical glass reinrorced plastil:sr.s-.7o.
Considering the cost and performance, the)' stand ill
between glass and carhon fibres. The spel'ifil: ll1(ldlllll~
is very high ror Kevlar and the lise or these fihres ill
place or a alulllinium parts in airl:raft rl'duces t hL'
weight by 40 ':;; .
if'l the 'sense that heat treatnll"l1t .',. th,-s," mwrs Illllst I", SUIlII1Ulr,·
({ecen't developmcnts in various aromatic polydonc at or above 250'C. It has becn observed that thc
wholly aromatic fibres arc amorphous in nature. amides are reviewed with em[)hasis on their prepara- "
However, many ot these are crystallizable, especially lion, structure-property relationship and proccssability '.'.
while being oriented at high temperatures. Stretching lit to convert them to suitable fibres. Latest tFends in~~\
highlelllpe.r/lhii'es, despite practical problems, is a research on these fihres and their applieatibns :Ire·
(-,
desirable reaturc since maximulll orientation is needed .: also indicated,
ror ensuring .opti.ilum properties. The·Jess effective
methods; such as treatment of fibres under high Ucferences
~
I. MARK,.Jj., AttAS, S.M. & OGATA, N., J. Pol),III:·Sci.. 61
pressure steam, wilh solvents or solvent mixtures at
(l9(,2);'·S49.
100'. etc. are also employed to improve the properties .. '
The Illethild generally used is stretching at higher .;·2.: '. Ff.I)(JTqVA. O. YA .. ~~r.\()kofl",/<,k Soedi/l.. 6(~) (19M), .
temperatures under. inert atmospherc as shown in
452. '
Tablc 2.
-.3. 'CIfIMUilA, K" TERADA, B., MAEDA, Y., KAWAKUIIO, 1-1.,
The Nomex fibre retains its original tensile strength
,..... SASAKI, T.& SBINOO. ~L ehe/l~. Alls/,... 83 (1975),
lip to 2S0nc and is userul IIp·to 30()"C. Thc hetero113.53.
' .,
4. KOSAI, K., TAIlI'. Y.. MA~UNA<JA, E.. & MATsunA. K.,
cyclic polyamidc fihre~ arc therl1lallym()f'c ~tahle IIp,to
Chelll. Aim,. .. H3 (197~). 44595.
4(JO 'C.
If lhe lihres arc to he IIsed in air. heat agelng
MORGAN. P.W, &. KWOLU':. S,L. IIfakmrl/(/ln'lllc.'. Htll
i~ done in air, the-properlies arc retained lip to 1-2
(1975). 104
week <, In !!eneral. they h;1\'e high volume resistivity
(,
VOSfflZAW ...... Y .. I L\/IT\tl. S. II\;, N"~"'lA. ~ .• r"ly",. 11"11 ..
and hi)!h dkkl'lric stren!!.h III' to a fairly h.i)!h tCIII'
HIll (1'172). ).15,
1',."ra'III" which makes them ~lIjtahk 1'111 sOllie spcl'i:i1
7. IJINE-HART, It.A .• J. 1'11/.1'111. Sri.. 211 (1964),369, .
NOI1l~x nylon papers"". In view of their cXl:cllcnl oxi8.' PRF$TON;·J. &;DORINSON, F., J. ·Po/j·;". S(i.. 211 (1964).
dation and chemical resistance, Nomcx fibres.are used
Ji71.
(1n fabrics ror I;igh temperature :protection. At 28S"C,
MAOhT, E.!:.. US l'iII. 2. IlJ I, RJ4 (to E." du I'ont de
'J.
thc fihrc is ::::: SO '~{, a~ strong :IS it is ;11 room tcmpc... lNemours & Co.). n April 1958; ellelll. Ab,'fr., 58 (1959).
tllre and shows similar relention of I11Cdllh.s. II~
1768.
oxidation resistance makes it retain the origin<ll
slrcngth. evcn after exposurc ror 1000 hI' at 2ClO" and '0. ~rl'\TN~ON. U .. GAll"IA!'''. (t,A. & VOGL. 0., 1',,1)'111.
I'repr .. 15 (1'174). 42(i.
ror 20(l hI' at 300"('. The fihre docs nol melt and
11. I\'fcHU.iA!'>, 1'. \V' Com/clIsoli"" l'o/.rlll(·I',\': /,,(rrrflC;U/ tllld
ignites IInly wilh dink-Illty: as sllch it is ~elr-exljnglljsh­
.\'O/l/fi'JII /IIefhocls (Inlcrsciencc John-Wiley & Sons Inc;,
jng and hel1\;~ is IIserul as a prolc~tive clothing. A
New York), t 965.
..
.' ~
similar lISe has been in the preparation or special type
or NOllle.x nylon papers. The polyamide papers, like 12. WrrrRlOCKER. E.!.. & MOIlGAN. I'.W.. J. 1',,/',"';11. Sci., 410
Ihe fihres. neithcr melt nor burn independently. The
(1959), 289.
ten,ile strength or the paper decreases grildllally wilh
lkAM,\N, R.G., MOIWAN, I'.W., KOLLER, C.R., WITTlln;temperature and at 22SoC becomcs 68%·of theorigi- 13.
KElt, E.L. & MAGAT. E.·E., J. PO/.~·III. Sci.. 40 (1959),
nal \'alue. In general. they have high volllme resisti329.
vity (1·3 x 106 ohm cm)and high dieleclricstrength
MORGAN, P.W, &. KWOL/'K. S.L. J. 1'''/.1'111; Sci .. 62 (1962),
even at high temperatures.: A major advantage or 14.
JJ.
these pap;:rs is in heat sealable application and high
tcrnp:ratur.: dielectrics ror usc in motors and trans- 15. KATZ, R.M,. J. 1'''/.1'111. Sci" 40 (1959), 337.
C). (,. :-"
1\~
j'
_.- .--- ---- -----_._--_.----
P~LYAMIDE
j
~
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J
. 51'!
.,
." "J\f,~"
.. ";'·'/'l~{;~~~~~!~" .
..
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.I. SCIENT. IND. RES., VOL 37, OCrollER 1978
16.
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2 (I %0). i 10.
44
17.
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J (1%1). 144Y.
SCIJ.;,"'II\'. I.B, (t:. 1("111\1, T,V., Vno/.tI",okl. S"rdill .. 2
(1""0). (,<)1(,
45.
IX.
I.f l,
TlJIIHSI;fI. L.V.
I"HIIOVA, YA.,
20.
K"nftflt. M,L., I.osrv, 1.1'. It: (;f'';f..'J~:'.
,<!'.\utilll/O/,·/'" ,\iw'/ill., 2 ()fHn)). 1020.
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··1(,.
1'7,
,I;:'
"1'1)0',,,,,;\, fJ,YA., KI:UItl:H, ~1,L .• l.oS,·\,. I.P., G, ~KI"'\'
<i.K. &
DYN'NA,
L;ll, Vysokolll(Jlek S(I('''i"., 3 (1961).
22.
1.1.
24.
25.
26.
~7.
28.
O. Y A., KEnnER, M.L. & 1..0SFV. 1.1'., "),mk".
lIIol<'k Socdill., 3 (1961), 1528.
H'LL. H.W., KWOI.n:. S.l. &. MORGAN, 1'.\\'. (I" FI. tI"
I'onl .I" Nellllllll" & ClI.): F,.. 1',,/. I. 199. 4(~'. ,., 'kcclll'
kr. I')~'.I: I..'S 1',,/. J.(lIlI•• I1!)!}•.11 Ckl""..... (1)(,1.
PIChi f '-'. N.J.T. & HI:-~sfln \\'OI)!). C.N .. .f. f 111'111. S'U',
FFIl'HOVA.
49.
~O.
51.
52.
(1936), 1353.
53.
A.N. & H'NSIIEI.\\·OOD, e.N., J. C"CII/. Soc .• (1958),
4085.
.
VrNK,\TARM'AN. I-I.S. & "'NSII(LWOOf), CN .• J. "/'('111.
54.
Soc .. (1960), · 1 9 8 6 . 5 5 .
KWOI.I'K, S.I.., .MOII~;AN, I'.W., & SUIIENSEN, \V.R., US
I'a/. J,OliJ. 966 (10 E.I. du Pont de Nemours &. ('(l.'). ~(,.
1.1 November 1962; Cltell/. Ah.,/,... !'II (196.1). 6964.
!\I{"F!'T. E.~1 .. l'I'ogn',fi.f ill IJ")'~fic(l1 (lrJ/f1I1h' di~·l1Iis(l:I·.
57.
V(,I. I (inlcr,cicncc Publishers Inc .• !'I,.\\, y,,'r~). 'I')(.J.
BOSE,
223.
SE;;;;:\"\' Y., AOK'. A. & MA';'SUO,\, K., C"('III. AIIII,.., 82
(1975), 172482...
BlINS'" I., A.lr:·,.1. ,~/"/(,/,. Sri., JO(8) (19'15). !JIm.
FW'II'AII.\. ''1'..
N . If,oswA. K .• TSUMA'~'. T .• UOl'fl. S. &
S .. ('/",1/1 . .'1"-,,,... RJ (1975), 120n.
('lIf~""tA. K., S'fI:-":""'~""T\'I., N,\t..:AMURA. \l .. KI\\\',\KUOO,
II. '" ~h"".I. Y., 0",1/1 .. • ·I!>.,,/,... HJ (1'I7~). f)')fl:lc.
NM;·"·\"·A. K., MIT"!;'"'. M., SlI7.IJI:', II. &. N'I'''II~II''''.',
'1'.. UIt'", . .-I!>.,/,... 11-1 (I<)7Ii). I2U9R.
S,\SAK'. A . .'I<. ~II\','MA, K .• 0'(,111. Ah.I/,..• 11.1 (197.~). 157(,89.
:''''''''~'' '1'., M'·I·"". H. &. 07.AII'A •. S .• (-'II,''''' Ah.I/,. .. !lZ
58.
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(1.1.
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&. IJ()II'NSON, F., J. 1',,/,1'111. S,·i .• 211 (1964),
& ll'-Ai::K, B., J. PiJl)'Iu.Sci., 4B (1966).267.
A.H .• .f. l'alYNI. Sci.; it (1913), i703 . .
HANI'ORI>, E.\\'. & SAUER, J.e., O''lfa"ic /'cnc/iolls, Vol.
III (.tohn Wiley & Sons fne.; New York), 1946, 108.
SONNTAO, N.n.V .• Cltelll. RCI·., 52 (1953),237.
Ff'llfI'ffJVA, O. YA .. Kmnr:'I, M .. !,. & LO~EV, 1.1'., V.I'.wlio
male" SOl'dil1., 2 (1960), 102.0'. ;..
PRESTON,-J;
GEllnER.
o
P,\·\,-'
M'.II'lj,\',
,\: I\.'.I;IIII"~. '·,.1 . ,\}O/.'''I11''/'·(/'/n
R.(i., MOnGAN, I'.W., K(JlI.I'ItA~r, c.n 8.:
WnTIII'·KEII,E.L" J, }'"(\',,,. Sd, 4011(1959), 329.
CON'X, /\ ..t., 111.1. E/IK,iK
51 (1959). 147.
MAliK. II .• AHA~, S.M. & OGATA. N .. J. /'0(1'11/. Sd,
(;1 (19(,2). ~49.
" " I. IL\\,. (.lit),
S.I .. '" S\\ITN'·. \I' .. US f'a,.
~,1I'.1:J.51 i Un I :,1. ,III POIlI tit' Nl'1l1tlllP, t~;. ( 'n,). IS Junt'
I '}("': Oil'''' . .. ,h.I·/" .. 59 ( I 'I(,J). III!(.',.
MEDVED. T. YA., FllUl'ZL T.M., HI:, ('.".1.. KI:I<AHlt",
,~'.V., KORSIIAK. V.V. & KORACHUIK, M.I., Vysokowal"k
S"ct/ill.. !' (196)), 1309.
I"IISION . .I .. .I. l·al, ..III. Sci.. 4A (1%6), 529.
I'II"S·I(''' . .I. &. S"I'I11, R.W .. .I. 1'"/,,,111. Sci .. 0111 <1%6),
II[,IMA:-:,
e/J""'''
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10.1.\.
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20!1.1.
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&. l'lH'STOS • .I., .I. 1'"l,r",. Sci .. -IA 119M,).
M!\'I~\'I.'.\.
K .. A(I:'. A .. NI~III11,\I<A. T. &. W~·I.\I(r. 1-1 ..
(,9 (197.1), 4.1584.
Go,.,. ;o..{, 110, S. & TANAKA. A .. Ch ..",. Ab.",. . HI (197,1).
65096.
KAI. .. "H"·A. V. D., Vys"k"III"lrk So('di".. IJ (1971).
707.
VOI.O"''':-:A. /\.V .. K.UMYKOVA. v.n. '" SO~Ol.o\·A, T.S.,
li'hilll. "')Iok., 17 (1975). I, 23.
NA("III:-:U", 0.1., YAI(O"OVA. I) .. SI'I"·I<AMKAYA. L.II ...
1'1 ~·I"N"VA. K.A., 10I'u\'A, M.M. & I'A"""", ·S.I' ..
('/',.'1/1,
79 (197.1), -1.15'9.
CiIl.\lII",I. K .. IW.ITA. II.. SII'NIU '. M. &. r-,'" ,iM. K., Ch"III.
Ab.I/I. 7'/ (I '.17.1). 1.\7105.
(,h,·!II . . ·I'·s/""
"'' .\'1' ..
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SM).H:', /\,. S,JV,\\th, 1<. & ~"':,\f(.\ ....\,\,.\, T .• ('hI'III. ,.i/',\/I',.
65.
8<1 (1976), 75553a, 91499...
. .... ,
K07.III, K., TAUE, Y., MASUNAGA, E. & MA1'SUIlA, K.,
Chelll. AllSIr., III (1974), 79308.
'.
.~
hr..
AII"STIIfINI1.
67n.
67b.
68.
K.IJ ... C"III/w.,'i/e.I·. 5 (19701),165.
1'01.1'11/('" "!;", 3 (to) (1972), 374.
PllIs/ies "lid Rubbe,. Weekly, 13 April, 1973.
J.T.. & ),oNNoLKLI, A.D.,' Che",., (lb.r/,:." 83,.
.'
,
(1975), 1'79679. . .'
HOGGART,
69.
RAS1'od"
70.
EAGLES.
A~, clll,,,,>rc,ii,;/OI., 5 «(i) (1975), 349.
DANA, II., ELUMtNTIII1"r, IJllucE, F. & COOPER
STAllln, l., J.
Poly",. Sl'i., 2() (1976), 4J5.'~},~.',i!~
(/",,1.
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Cliem. Ah.,/,.., 83 <.1975), 614,\7. ', ..' ..
MARK, H.i=., ATLAS. S.M. & OOATA, N:;~ J. I'o("m. Sci.,
61 (1962), 549.
I'III'SH'N, .I .. 1'01.1'11/. p,.el"' .. 6(1) (1966), 42.
(1%5J. '!'!').
F"\;IIP--:.i\"t.I,,(:, Ilfl\I·:·.:IIIA'.I\ .I., "/",',\1. Un .I.,~('fl(;(,.':;1.
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1.1,,111' \\,iil'y &. 50ns Inc .. New y",.~). 1'15.\ 122; U,O.
S,,,,,,va. II.S. <" S'Ma:no". H.W .. 1".1/. II".,· . .I.. 3S
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