Indian Journal of Fibre & Textile ResearchVol. 21, June 1996,pp.143-154

~

Review Article

Modification of acrylic fibres for specific end uses

P Bajaj & D K Paliwa]"Department of Textile Technology, Indian Institute of Techno]ogy, Hauz Khas, New Delhi 110016, India

and

A K GuptaCentre for Polymer Science and Engineering, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India10;

Received 3 November 1995; accepted 8 December 1995

Acrylic fibre is the third largest consumable man-made fibre in the world and is mainly used as asubstitute of wool. It competes with wool because of its properties like high elasticity and voluminos-ity. Modifications of acrylic fibres have been tried to make it suitable for different applications. Thispaper presents a comprehensive review of the acrylic fibres modified in recent past for different enduses.

Keywords:Acrylic fibre, Antimicrobial fibre, Flame-resistant fibre, Hollow fibre, Ion-exchange fibre,Water-absorbant fibre

1 Introduction .S yn thetic fibres have 40% share in total de- Table 1-Consumptiono~syntheticfibres

..lcurrent and projectedj2~ mand of fibres m the world1. Polyester, polYamIde

(nylon), acrylic anti polypropylene are the import- Consumption (in tonnes) Annua] growthth . fib d .. 1 Th rate %ant syn etlc res use m texties. ese to- ]990 1995 2000 '

..(1990-2000)gether account for 98% of the world synthetIc fi-bre production and consumption. The world-wide Polyester filament 3972 5000 6300 5.3consumption of these fibres is given in Table 1 Polyest~r staple 4718 5220 5745 2.2and the break-up of world production of synthetic Nylo~fllament 3013 3280 3730 2.4fib . h . F . 1 A 1. fib . th thi d Acrylic staple 2196 2465 2830 2.9

res lS S own m 19. .cry lC re lS e r1 bl d fib . th ld Total 13,900 15,965 18,605 3.3

argest consuma ~ man-ma e re m e wor

and has. a share 0: 20% of total synthetic fibre Break.up of World ProductionproductIon. The history of research for produc- of Syntheticstion of acrylic fibre began in early 1930s in Ger- ." 19.1,-r many. An experimental acrylic 'fibre for military (In million .tonnes )application was produced by Du Pont in early ~ Other syn.thetlcs 15.91940s in United States, and the production of the ~ Pol~cryllCfi .al 1. fib d b UI Polyester

rst COmmerCl acry lC re was announc.e y .Polyamidethis company in 1949 under the trade name 'Or-Ion 1949'. Since then a number of compani"eshave gone for production of acrylic fibre. In India,the Indian Petrochemicals Corporation Ltd start-ed the commercial production of acrylic fibres in1979. After that J.K. Synthetic Ltd and other

f~ three companies, namely Pasupati Acrylon Ltd,

.Present address: Department of Education, Ministry of Hu-man Resource Development, Shastri Bhawan, New Delhi 1970 1975 1980 1985 1990 199i.110001, India Fig. I-World production of synthetic fibres

--

144 INDIAN J. FffiRE TEXT. RES., JUNE 1996

Indian Acrylics and Consolidated Fibres, have 2 Acrylic Fibres with Enhanced Hydrophilicity

started acrylic fibre production. The scenario of and Dyeability

production of synthetio fibres in Jndia2 is given in Compact structure due to the strong. nitrile d~I?- ~

Table 2. olar interactions and the absence of hydrophilic

Acrylic fibre is traditionally used as a textile f'l- groups in homopolyacrylonitrile (PAN) is respon-bre in the apparel and house furnishing and has sible for its poor dyeability and hydrophilicity. In-

replaced wool in many major applications, parti- corporauon of a variety of comonomers has been

cularly in hand knitted and h6siery garments, tried to improve the dyeability, hydrophilicity,blankets and carpets. Acrylic fibre competes with flame retardancy, heat resistance, etc. of acrylic fi-

wool because of its high elasticity, colour brilli- hres. SmaJI amounts of certain comonomers have

ance, voluminosity, resistance to pilling, and co- be,en used to enhance the mobility of polymer

lour fastness properties. Acrylic fibre for. textile or segments to facilitate the diffusion of the dye

technical use has always been valued for its,resist-

ance to UV radiation, mildew, bacteria; etc. Its Table 3-Effect of coITion orner on the properties of acrylic fibre

low. specific ma,ss and adequate ela,sticity mak~ it Comonomer Prop~rty Ref. *

a~ ideal matenal for. the ~roductlon. of textiles Methylacrylate Improves solubility 11-12

With exceHent thermal msulating properties. Vinylacetate Improves solubility 11-12Acrylic fibres also have ~ome industrial,applic- Hydroxyalkyl methacrylate Hygroscopic with 13

ations, as in making filter cloth3.4, replacement of , good dyeabi~i~yasbestos fibre in reinforcement ,of cement5.6 in Sodium salt of p-~ulp~ophenyl Good dyeab.ilrty and 16; 7 -' -methallyl ether With VInyl acetate water retentionlon-exchangers ,.and as a precursor to carbon fi N-Vinylformamide/N-Vinyl Good dyeability and 17bres8-12 .d ' '

.' acetaml e water retentionFor a specific end-use, the acrylic fibres can be 2-Acrylamide-2-methyl propane-Good dyeability and 18

modified at the stage of polymerization or spinn- sulphonate. wat~r re~en~ionin and/or even after spinning 13-16. The effect of Poly~ethylene ~xI.de). Ant~stat~c ~bres 27

.g ..N-Vmyl pyrrohdme glycldyl me- Antistatic fibres 28different comonomers and dope additives on the thacrylate and N-(hydroxyethyl)

properties of acrylic fibres which make them suit- methacrylarnideable for specific end-use is .shown in Tables 3 ~d Qu~ternar,: s~lt of 1, 2-dimethyl- Ion-~xchange pro- -37 --<'

4 respectively. This paper presents an exhaustive 5-vmyl pyndl~e met~yl.~ulphate pertlesreview dealin g.with the modifications of ac ry lic fi- 2-Methyl-5-vmyl pyndme lon-~xchange pro- 37

pertlesbres. Vinylidine chloride Flame retardancy 44

Haloalkylacrylate/methacrylate. Flame retardancy 45Vinylchloride/vinylidine chlo- Flame retardancy 46ride and sodium salt of 2-acryla-"/", '

Table 2-Production (in tonnes) of man-made fibre/filament ffilde-2-methyl propane sulphon-yarD/lyre yarn ate

Vinylidine chloride and sodium Flame retardancy 47Item 199()-91 19~1-92 1992-93 1993-94 1994-95 methallylsulphonate

Staple fibresViscose" 160172 158078 .16243Q 183338 173112 Table 4-Effect of dope additives on the properties of acrylic-~lyester 134207 13615'9 161822 200062 221075 fibres YAcrylic 42822 45872 ;,60'j?7 6~35~ 82743 ..Polypropylene' 993 860 1223 1585.. ,1704" Dope additive Property j{eference

Total' 338194 340969 381562 453344 478634 FibrQ~andcollagen Increase in strength; fibreFilament Yarn with uniform structure and

Viscose 50942 52683 47950 53010 58528 morphologyNylon 39888 30690 32690 38129 39366 Milk casein Exc?ptio~l build up pro- 15~lyester 185241 206499 246285 288664 297922 pertles With good dye-

~1ypropylene 3864 5776 8549 10390 10572". u~take, ,Total- 279941.295648 335474 390193 406388 Polyvmylacetate High water retentlvrty 24

Polystyrene High water retentivity 24Tyre yarR Cellulose/cellulose High water retentivity 25

Rayon 7573 7811 8518 10227 9288 derivative ~Nylon 37244 37278 42033 43330 45149 Hydrolyzed waste of High water retentivity 26

" Including HWM fibre acrylic fibreb Provisional Block copolyether Antistat properties 29

Source: Association of Man-made Fibre Industry! Association Antimonyethoxide Flame retardancy 49of Synthetic Fibre Industry. Tributyl phosphate Flame retardancy 50

,

BAJAJ et al.: MODIFICAll0N OF ACRYUC FIBRES 145

molecule and thus improving the dyeability. In- lymer and claimed good handle and level dyeingcorporation of neutral co monomers such as me- of fibres.thacrylate and vinyl acetate (V Ac) improve the Improvement in dye levelling has also beensolubility of polyacrylonitrile'3.14 and thus facili- claimed by Mitsubishi Rayon Co. Ltd}K by pass-tates the formation of spinning dope as well as. ing the acrylic fibres around a concave heater'the spinning. of the polymer. These comonomers plate with surface temperature of 150- 300°C withappear to increase the amorphous content in the difference in yam tension' before and after thepolymer and bring down the glass transition tem- heater.perature ( ~). Apart from the modification at polymerization

Attemptsl3-20 have been made to produce hy- and spinning stages, chemical aftertreatment ofdrophilic acrylic fibres by copolymerization of ac- acrylic fibres has also been used to improve fibrerylonitrile (AN) with vinyl comonomers contain- properties. Hydrophilic acrylic fibres having ex-ing hydrophilic functional grollcps, such as hydrox- cellent moisture absorbance (12% at 65% RH)yl, ether, carboxyl, amide, etc. and water retention29 were prepared by soaking

Acrylonitrile c9polymers containing 1-4.8 mole the tip of hollow fibres spun from AN-methacryl-% hydroxyalkyl methacrylate comonomer21 were. ate copolymer in 40% NaOH, depressurizing andfound to give hygroscopic fibres with good dyea- heat treating the fibres at 98°C. Fibres from AN-bility. Poly(acrylonitrile-2-hydroxypropyl methac- methyl acryla:rnide copolymer were immersed inrylate) copolymer fibres with 4.26 mole % of the an aqueous mixture containing 60% H2SO4 atcomonomer had a moisture regain of 2.4% at 60°C for 10 min to produce hygroscopic acrylic65% RH. The dye uptake of Astrazon Yellow of fibres with knot strength of 2 gpd (0.17 GPa) andthe same copolymer fibre was 6-.7-. times higher water vapour absorption of 5.6 wt%.than that of the corresponding PAN homopolym- Toray Industries3o claimed fibres with improveder fibre. hygroscopicity and sewability by treating AN-

Addition of fibroin and collagen to the spinning polyalkylene glycol mono(methacrylate) copolyrn-dope has also been reported22. Addition of 20% er fibres with compositions containing C25-33 hy-of these compounds increases the strength of drocarbon, an ester, an a:rnide, and/or a water-

--PAN fibres, particularly its resistance to repeated soluble silicone and a poly(oxyethylene) surfact-deformations22. These fibres have a uniform ant.structural network and morphology.

Toyobo Co. has also reported2O the use of milk 3 Water:-Absorbent Acrylic Fibrescasein as the amorphous portion and PAN as the Acrylic fibres with high water absorbing powercrystalline portion for developing Chinon, a silk- hav~ been produced by creating micropores andlike fibre. An outstanding characteristic of Chinon increasing their hydrophilicity \?y using suitablefibre is its dyeability. It has shown an affinity for comonomers. Microporous structure may bevarious classes of dyes (acid, pre-met~llized, mor- developed by conjugate spinning, i.e. by spinningdant, direct and basic) and exceptional build-up polyacrylonitrile with another polymer of lowerproperties. molec!llar weight. Bayer Co. succ~ssfully intro-

Yoshinori and Yoshihiro23 have reported the duced high water-absorbent acrylic fibre with-production of acrylic fibres with good dyeability brand name "Dunova" in 1976 and thereafter si-

and water retention by polymerizing acrylonitrile milar product~ have been developed by some Jap-with vinyl ~cetate and sodium salt of. p- anese companies31.32. Researchers33 at Chinasulphophenyl methallyl ether 'Or blending with cel- Textile University have d~veloped water-absor-lulase, fibroin and polya:rnide24. Other comonom- bent acrylic fibre with a total water content of 20-ers such as N-vinylforma:rnide and/or N-vinylacet- 35% of the fibre weight. .

a:rnide, sodium 2-acryla:rnido- 2-methylpropanesul- The enhancement in microvoids an<;i water ret-phonate have also been used19. The use of com- entivity of fibres has been achieved by spinningonomers' having acidic" and basic groups is report- acrylic polymer with a small amount of secondaryed to manufacture basic and acid dyeable acrylic polymer such as polyvinylacetate, polystyrene, ac--fibres25.26. rylonitrile-styrene' and acrylonitrile-vinyl acetate

Kanebo Ltd27 has patented a process to manu- copolymers 19. Bajaj34, in association with Pasupatifacture hygroscopic acrylic conjugate fibre by Acrylon Ltd, has developed a new hydrophilic ac-spinning equal mixture of acrylonjtrile-acrylic acid rylic fibre with 25-35% water absorption andand acrylonitrile-methacrylate-sodium found it most appropriate for the climatic condi-2-acryla:rnido-2-methylpropanesulphonate copo- tions prevailing in tropical countries. S~eci.fic sur-

146 INDIAN J. FIBRE TEXT. RES., JUNE 1996 i :,..

face area and pore volume of. th~ acrylic fibres Table 5-Charge dissipation in acrylic fabric treated with 2%

could also be mcreased by spInnIng a blend of NaOH in steam at 100.C

polyacrylonitrile and hydrolyzed waste from ac- Treatment time Dissipation rate ~

rylic fibre manufactilre35. min Volts/min

Untreated 9.64 Antistatic, Soil-Release and Conductive Acrylic 15 15.2

Fibres 30 17.0

An '. . be . d li 45 18.6

tlstatlc properties may lffiparte to acry c 60 20.6

fibres by increasing their hydrophilicity and electrical

conductivity. This may be accomplished by copolym-

erizing AN with comonomers such as poly(ethylene

oxide), N-vinylpyrrolidone, glycidyl-methacrylate izable vinyl monomer containing an ammonium,

and N-(a-hydroxyethyl)methacrylamide36. Copo- sulpho or carboxyl group, and then irradiating the

lymerization of AN with poly(ethylene oxide) is re- fibres. Semiconducting acrylic fibres of good me-

ported to confer antistatic characteristics to acrylic fi- chanical strength, hydrolytic stability and electri-

bres. Copolymerization of N-3-oxohydrocarbon cal resistance of 103-1012 ohm cm -1 were ob- +

substituted acrylamide and poly(ethylene glycol) ac- tained43-45 by treating the fibres with SnCl4 and

rylates or methacrylates was also reported to provide copper sulphate46.

another route to antistatic fibre production37.38.

5 Ion-Exchange Acrylic Fibres

Antistatic acrylic fibres were obtained by the Acrylic fibres with ion-exchange properties

addition of block copolyether-ester to PAN spinn- have found their application in recovery of rare

ing solutions. The permanency of the antistatic ef- metals 15 such as ruthenium, osmium, uranium, etc.

fect was influenced by the conditions of coagula- Ion-exchange acrylic fibre has been used as a sec-

tion. It was found that poly(ethylene oxide) exert- ond downstream ion-exchange unit for removal of

ed the greatest influence ~ lowering the electrical zinc ions from industrial effluent. Ion-exchange fi-

resistance. Polymeric additives in the fibre spinn- bres are produced from a copolymer comprising

ing dope include polyester/polyether block copo- acrylonitrile and the quaternary salt of 1, 2-dime-

lymers, diacrylic ester of poly(ethylene glycol) and thyl-5-vinyl pyridine methyl sulphate or 2-methyl- -..('

sulphur containing polyethers. 5-vinyl pyridine and also from poly(acrylonitrile-

Brown and Pailthorpe36 have listed a number of methyl vinyl pyridine) copolymers26. Attempts

formulations for the production of antistatic acryl- have also been made to produce ion-exchange fi-

ic fibres. Acrylic fibres can be made conductive bres from mixtures of PAN and poly(ethylene-

by spinning from a mixture containing electrocon- imine). Inorganic groups47 into PAN have also

ductive fillers such as carbon black, antimony ox- been introduced by alkaline (sodium metasilicate

ide, tin oxide, titanium dioxide, ammonium or and NaOH) or acid hydrolysis.

n:tetal salts or copper ions.

Treatment of acrylic fibres with solutions con- 6 Antimicrobial Acrylic Fibres

taining copper sulphate, sodium thiosulphate, so- The introduction of certain inorganic salts, viz.

dium citrate and basic dyes imparted antistatic, AgN°3; Hg(NO3h, Cr{OCOCH3)3' K2Cr207, r-

antiseptic and deodorant properties in them39.40. Pb(OCOCH3h, etc. into acrylic fibres imparts

Antistatic and soil-release acrylic fabric has been bactericidal or antimicrobial activity48. Courtaulds

prepared41.42 by modifying the fabric surface by have claimed the development of a high perform-

partial saponification with 2% NaOH. Such sur- ance acrylic fibre, Courtek M, which can prevent

face modifications increase the charge dissipation the build-up of hazardQus bacteria in cloth fur-

rate (Table 5). nishings and medical equipmentsl6. This fibre is "",

Another approach to antistatic acrylic fibres reported to have combinations of antimicrobial "

was disclosed in a patent40 in which a copolymer compounds based on metallic salts. The com-o containing 86% AN, 11% VAc, 3% dimethyl pounds are bound into the fibre matrix, which

aminoethyl methacrylate is spun into fibres and means their effectiveness is not minimized by , then treated in a solution containing copper wear or washing. Courtaulds predicts that this fi-

sulphate and hydroxyl amine sulphate bre will find many applications in industry and

[(NH2OH)2H2SO4]. clothings required in hospitals, food processing or

Antistatic and hydrophilic properties of acrylic intimate apparel, where the build-up of dangerous

fibres were improved by treatment with polymer- bacteria can be unpleasant or a hazard to health.-

BAJAJ et al.: MODIFICATION OF ACRYUC FffiRES 147

In many patents49-S2, the production' of antirnic- A blend of two fibres-".A;.' (spun from acryloni--robial fibres by incorporating quaternized N-con- trile-sodium 2-acrylamido-2-methyl propanesul-

taining antibacterial groups or antibacterial ele- phonate copolymer) and "B" (spun from vinyli-~ents comprising Ag, Cu, Zn, Hg, Sn and/or dine copolymer containing antimony pentoxide,their oxides has been claimed. Sb2Os)-prepared by Kanebo Ltd62 exhibited LOI

Toyo Bosekiso has claimed the production of 34, low heat. shrinkage and good mechanical spin-antibacterial acrylic fibres by treating acrylonitrile nability. Mitsubishi Rayon Co. Ltd63' has claimedcopolymer fibres containing the manufacture of fire-resistant acrylic fibresCH2=CR1CO2R.4NR2R31Rl=H, Me; R2, R3 = with improved transparency from spinning solu-Me, Et; R4 = CH2CH2, (CH2)3' tion containing acrylonitrile-sodium methallylsul-CH2CH(OH)CH2] with alkyl halide to form qua- phonate-vinylidine chloride (58.5 : 1.5 : 40) terpo-ternized N-containing antibacterial groups. A so- Iymer and 3.0 parts of antimony ethoxide. Tsai64lution of acrylo~trile- Me acrylate-sodium, 2-acry- has studied the effect of tributyl phosphate, tri( di-lamido-2-methylpropanesulphonate polymer, 5% bromopropyl)phosphate, aluminium hydroxide,

" novaron with 3.0% Ag content and 10% acetyl calcium phosphate, antimony oxide on flame re-cellulose were spun to give hygroscopic light-re- tardant properties of acrylic and modacrylic fi-sistant fibres with good antibacterial propertiesSl, bres. Tin oxide. has also been used6s for produc-A Japanese patentS2 has claimed the production ing fire-resistant acrylic fibres.of acrylic fibres with excellent heat insulation, Inexpensive fire blocking fibres are oxidized ac-odour-absorbing and antibacterial properties by rylic fibres like Panox. Kermel [poly(amide-imide)Jspinning acrylic polymer solution containing a and wool represent a very useful combination formixture of silicic acid, aluminium oxide, silver and producing comfortable fabric to wear when theammonium hydroxide. Kanebo LtdS3 have also going gets hot66. R.K. Textiles is one of the manu-prepared a fabric exhibiting 94% and. 99.2% bac- facmrers of oxidized PAN fibFes which are used interia reduction power for Escherichia coli and advanced carbon/carbon brake disc for aircraftKlebsiella pneumoniae respectively by dispersing filld fire-r~slstant barrier fabrics. K067 has pro-0.5% Novalan (a bactericide) in polymer solution duced non-flammable fibres from polyacrylonitrile

-containing acetyl cellulose. Use o~ 3, 4, 4'-trich- fibres: by a continuous stabilization process.. Helorocarbanilide as bactericide and hydroxy ben- has also studied the t:ffect of sht:inkage behaviourzoic acid esters as fungicides has ,also been made and stretching during stabilization on physicalfor producing antibacterial acrylic fibress4. properties, morphology and flammability of the

resultant non-burning fibres. Kanebo Ltd68 has7 Flame-Resistant Acrylic Fibres dis'closed a process for making fire-resistant acryl-

The flame retardancy of the acrylic fibres ic fibres with good weaving quality and LOI 42(LOI-18, the lowest among textile fibres) can be by oxidising acrylonitrile-sodium-2-acrylamido-2-improved through modifying it by incorporating methylpropanesulphonate copolymer fibres athalogen or phosphorous containing vinyl comon- 250°C under tension for 15 min and then coatingomers such as vinylidine chloride and vinyl bro- them with 2.5% guanidine phosphate. Zhang and

r mide!3 which increase the energy required for coworkers69 have also studied the role of ammo-burnIng. nium polyphosphate in flame retardation of acryl-

Self-extinguishing modacrylic fibresss-s8 have ic fibres.been produced from a terpolymer containing AN(35-85%) and vinylidene chloride or vinyl chlo-ride (5-30%). In another studyS9, AN copolymer 8 Hollow Acrylic Fibrescontaining 2-9 mole % haloaikyl acrylat~ and/or Hollow acrylic fibres find their use in making Imethacrylate has been used for producing hygros- insulative garments 70 and in preparation of mem-copic and flame-retardant acrylic fibres. A polym- branes for water treatment in food, pharmaceuti-er of acrylonitrile, vinyl chloride or vinylidine cal and electronic industries and in nuclear power

, chloride, and sodium salt of 2-acrylamido- plants71. These fibres are also found useful as pre";2-methylpropanesulphonate was reportedly6° spun cursor to carbon fibres 72, because they may dis-:into fibres with LOI of 29.4 and good transparen- sipate heat more effectively than the conventionalcy. acrylic precursors.

Mitsubishi Rayon Co. Ltd61 has used AN ter- Toray Industries7o.72 have disctosed a process to]polymer with vinylidine chloride and sodium me- manllfacture hollow acrylic fibres by spinning a Ii-

thallyl sulphonate to produce fire-resistant fibres. quid containinE, acrylonitrile-methacrylic acio cop- ~

.,

148 INDIANJ.FIBRETEXT.RES.,JUNE 1996

olymer as a sheath and polyvinyl alcohol as a 100core. The resultant hollow acrylic fibre was used 100 10 -..,{to produce hollow carbon fibres jor use in com- I 0.T Ind . ha al N DOLANITposites. J. oray ustnes s so patented a pro- E )(cess 71 for the manufacture of hollow acrylic fibre ~ 800 ~membranes containing pore dia ~ 0.1 ~m for z 0 -;;:treatment of water at large scale for food indus- ~' 600 ~tries. Mitsubishi Rayon Co. Ltd73 has produced ~ t:hollow acrylic fibres with good crimping property ~ 400 40 ~

from acrylic polymer containing acrylonitrile ~ ~(92.8%), vinyl acetate (6.95%) and sodium me- ~ 200 0thallyl sulphonate (0.25%). t-

Mitsubishi Rayon Co. Ltd74 has also claimed~e production of sheath-core bicomponent fibres 00 5 10 15 20 25 0

through a spinnerette having holes comprising a E LONGA TICN 0'0 ~channel for the core component and ~ 3 chan- 'nels for sheath component. The fibres had acry- Fig. :!-Slress-slrain curves .for. Do!ani! fibres and a Dolanlonitrile-heptadecaflurodecyl methacrylate copo- textile fibre"

lymer as the sheath and acrylamide-acrylonitrilecopolymer as the core. The process to producehighly asymmetric hollow acrylonitrile fibre' ...,-..Table 6-Effect of acid and alkali on mechanIcal propertIes ofme~bran~s With lar~e pores and mt~rnal su~aces RICEM (1.5 dtex) [ref. 39]efficient m separation has been disclosed m a Treatment Tenacity Elongation Modulus ResidualGerman Patent75. cN/tex % cN/tex tenacity, %

Untreated 77.0 9.4 2154 -9 High Performance Acrylic Fibres In 50% H2SO4 at

Attempts were made to develop synthetic fibres 20.Cto replace carcinogenic asbestos in fibre-rein- after 7 days 76.3. 9.4 2088 99 --(forced cement products e.g. in flat roof shee~ ~er 30 days 76.0 9.4 2070 99

.' .after 60 days 75.2 9.4 2069 98and facmg slabs, corrugated sheets and discharge In 30% HNO atand vent pipes. Polyacrylonitrile (PAN) appears to 20.C 3

be a good choice because of its good cheInical re- after 7 days 77.3 9.8 2133sistance in alkaline media4.16.76. Hoechst AG have after 30 days 77.6 9.2 2231 100developed acrylic fibres (Dolanit) of different after 60 days 76.9 9.6 2123

4' :_4" 5 Th .After soaking intypes .lor rellllorcmg p~rpose: e st~ess-stram NaOH (pH 13) at 69.3 9.8 1721 90behaviour of these mdustnal acrylic fibres 80.C for 24 h(Dolanit: 10, 11, 12 and 15) has been comparedwith that of textile-grade acrylic fibres (Dolan .37)in Fig. 2. Fibre-reinforced cement sheets contain- -ing 2% (by wt) Dolanit 10 and 4% (by wt) cellu- ment of cement structures. Mitsubishi Rayon 'T-'

lose were foUnd suitable for building material. CO}9 has also disclosed the manufacture of acryl-Monte fi6res have prod~ced a high-modulus ic based bicomponent fibres for reinforcing ce-

PAN fibre77 (RICEM) to be used as a reinforcing ment. An aqueous slurry containing 200 parts ce-medium for cement matrices 'as an alternative to ment, 4 parts 5 mm long acrylic fibres and 4~bestos as well as for eliminating cracks in mor- parts pulp was formed into a board and cured attar or concrete in the curing stage. Flat sheets 25°C for 15 days showing flexural strength.of 130

made with 2% RICEM and 3.5% pulp fibres kgicm2.showed the same bending strength a~ sheets pro- It is apparent that acrylic fibres with highduced with 15% asbestos. In addition, the boards strength and modulus are spun from PAN ofproduced with RICEM are found to be less brit- higher molecular weight which needs some modif- ---y-

tie and absorb a great breaking force. The effect ications in the conventional wet spinning by pro-of acid and alkali on the mechanical properties of viding multistage drawingI6.8o-84. It enables a wideRICEM is shown in Table 6. range of properties by varying the spinning par-

Toray Industries InC}8 has produced water ab- ameters, as listed in Table 7. The denier of the fi-sorbing high strength acrylic fibr~s for reinforce- bre depends upon the spinnerette orifice diame-

, ". "', .

BAJAJ et al.: MODIFICATION OF ACRYUC FIBRES 149

Table7-Influence of spinning conditions on the properties of high strength acrylic fibrePolymer Solid content Spinning conditions Properties of Ref.composition in dope fibrewt°/c °;'° ° Wet Spinning

AN (98.65) 10 AI = 3 in coagulation bath Tenacity, 1.035 GPa vs 0.66 GPa for fibres 74MAA (1.35) Az = 4 in boiling water not stretched during cooling

AJ = 1.8 at 150.C Modulus, 16.56 GPaA4 = 1.5 during cooling

AN 20 in DMF Coagulation bath composition, DMF: H2O Strength x elongation = 240 vs 109 for fi- 67MA ' (75:25) bres spun in bath containing 55% DMF and

Sod. MAS Coagulation bath temperature, 25.C 80s residence timeResidence time in coagulation bath, 9s

AN (98) 12, inDMF illR=6 Tenacity, 0.807 GPavs 0.376 GPaforfibres 75MA (2) containing 2% spun from dope having 8% solid contents

whter Elongation, 5.3%AN (96) 5, in DMF + ~pinning temperature, 1l0.C. Fibres were Tenacity, 1.5G-P~; Modulus, 17 GPa vs 0.7 76MA (4) ZnCI2 passed through a bath containing dichlor- and 12GPa respectively for fibres spun from

Zw + :AN units omethane and then water dope without Zn2 +

1:50AN 6, in DMSO Coagulation bath composition, DMSO: H2O Tenacity, 0.614 G.Pa

(50:50).Extracted with water for 184s at Modulus, 12.1 GPa 84

22.C drawn in two stagesAN (93) 5.5, in 60% aq. Coagulation bath composition, 29% aq. Tenacity, 0.54 GPa 77

MA(5) ZnC12 ZnC12 Elongation, 21%IA(2) Total draw ratio, 18; Relaxed at90.C Diameter, 0.18 GPaAN (78) Solution in aq. Gelled in aqueous HNOJ, dried and set at Tenacity, 0.93 GPaMeAN (20) HNOJ 20.C for 20s Modulus, 0.18 GPa. 85 .

MA(2)AN 2.9, in 50% Coagulation bath composition, 15% aq. Tenacity, 1.68 GPa Modulus,aqueous NaSCN 23.85 GPa 78

NaSCN Coagulation bath temp, room temp.Drawing temp., 220.C

AN 5, in 50% Coagulation bath composition, 10% aq. Tenacity, 2.20 GPa 79

NaSCN at NaSCN80.C Coagulation bath temperature, 5.C

AI = 2 in H2O at 85.CAz = 2.5 in boiling waterAJ = 1.8 in ethylene glycol at 130.CA4 = 1.6 in ethylene glycol at 160.CTDR = 14.4

Dry-Jet Wet Spinning

AN (99.J) 20 Treated with ultrasonic waves, 50 W, 30 Hz --73

IA(0.7)AN 10, in DMF Coagulation bath temperature, 21.C Tenacity, 1.08 GPa

Benzyl alcohol AI=I.8inboilingwater Modulus, 17.19GPa 82was added as A2 = 3.5 at 170.CadditiveAN (> 78) DopeinDMF Coagulation bath composition, DMF: H2O Tenacity, 1.57 GPa 86at 45.C (83:17). Modulus, 17.2 GPa

Coagulation bath temperature, 20.C Orientation, 96.1%

AN 5, in 50% aq. AI = 2 in water at 85.C Ten'tcity, 1.65 GPaNaSCN A2 = 2 in boiling water Mooulus, 32 GPa 83

AJ = 1.8 in ethylene glycol at 130.CA4 = 1.6 in glycerol at 160.C.

AN-acrylonitrile; MeAN-methyi acrylonitrile; MA-methacrylate; MAA-methacrylic acid; lA-itaconic acid; Sod. MAS-so-diummethallylsulphonate; A.-1st draw ratio; A2-2nd draw ratio; AJ-3rd draw ratio; and A4-4th draw ratio.

ter, the through-put rate and the take-up velocitY, orientation and mechanical properties. The orien-while the stretchability (elongation-at-break) de- tation of the molecular chains is easy in the gelpends upon the stretching of the fibre in the spin state because the trapped solvent decreases theline. The gel fibres are stretched to obtain better cohesive forces among the nitrile groups of the

---

150 INDIAN J. FIBRE TEXT. RES., JUNE 1996

polymer chains85. The stretching of gel fibres re- Co. Ltd disclosed a method to produce highsuits in the unfolding of polynter chains and in strength (2.20 GPa) acrylic fibres by spinning a ~the formation of an oriented network morphology 5% polymer solution in 50% aqueous NaSCNwith a relatively homogeneous distribution of and stretchiRg the fibre in different media 15 to apores and void size. total draw ratio of 14.4.

Gupta et a/.116 have demonstrated the effect of Dry-jet wet spinning techniqueI6;87-S9 is used tohot-wet draw ratio on the coefficient of friction of produce fibres with higher strength and modulus.wet-spun acrylic fibres using DMAc/water m.:x- This technique is similar to wet-spinning exceptture in the coagulation bath. The measurements that the fibres are extruded a few mm (8-10 mm)of friction by both the line and the point contact above the coagulation bath so as to achieve mo-methods was carried out on an Instron machine lecular orientation. It has certain advantages overusing a traverse rate of 0.5 in/min. It has been wet spinning such as higher spinning speeds, cap-demonstrated (Table 8) that orientation factor in- abl~ of producing fibres of finer linear densitycreases with cascade stretch but the rate of in- ( < 1 tex), spinning of dopes of high concentration, ~crease gradually dropped with the increa.~e in and control of non-circular cross-section of fila- ~stretch ratio. A linear correlation has been found ment. The filaments spun by dry-jet wet spinningbetween the molecular orientation and the inter- are stronger and have more elongation than thefibre coefficient of friction in wet-spun and hot- fibres spun from immersed jet. The dry-jet wetwet-drawn acrylic fibres. technique allows relaxation in the air gap of the

The treatment of acrylic fibres with ultrasonic orientation produced in tne spinnerette so thatwaves in a coagulation bath has also been report- the spun fibre is less oriented and more uniformed to .produce improvement in strength and re- than from the immersed jet. This permits higherduction in tenacity variation along the length of and more homogeneous orientation by subse-the fibrel5. Acrylic fibres of increased toughness quent drawing.and tenacity (1.03 GPa) were produced by Japan Acrylic fibres of 1.08 GPa tenacity and 17.2Exlan Co. Ltd 15 by stretching the. fibres during GPa modulus were prepared by Toyobo Co.

cooling. The fibres not stretched during cooling Ltdl6. Japan Exlan Co. Ltd has produced acrylic -Iwere reported to have lower tenacity (0.66 GPa). fibres with high tenacity (1.65 GPa) and modulusFibres spun into a bath having higher concentra- (32 GPa) by stretching the fibres in ethylene gly-tion (75%) of solvent showed a higher strength x col anq glycerol.elongation product of 240 as compared to the fi- 10 Acrylic as a Precursor to Carbon Fibresbres spun in a coagulation bath with 55% solvent Among various precursors for carbon fibre,content and a residence time of 80s which had a PAN has wide acceptability due to high carbonstrength x elongation product of 109. yield and flexibility for tailoring to desired pro-

The void content in the fibres may be reduced -duct9O-95. The weight loss at 1000°C in helium isby increasing the solid contents in: the dopel6. Sta- quite low for pre-oxidised PAN fibres as com-01i Carbon reported improvement in the mechani- pared to other precursors for carbon fibre. Tocal properties of acrylic fibres spun from a solu- produce good quality carbon fibres, special acryliction containing Zn + 2; fibres (SAF) are required, which are reportedly ~-

Kuranay Co. Ltd patented a process to produce spun from the polymers having moderate molecu-acrylic fibres of high tenacity (1.68 GPa) by draw- lar weight and molecular weight distribution with .ing the fibres in air at 200°C. The Japan Exlan minimum molecular defects. Conversion Qf SAF

.to carbon fibres is shown in Fig. 3. SAF shouldTable 8-Effectof cascade str~tch on th~ S?nic modulus o~~en- have fine denier (10-12 11m diameter), high

tation factor and the coefficIents of fnctlon.of the y~r~s -strength and modulus, should show a broaderSample Cascade Sonic Average coefficIent of frIction DSC exotherm with low threshold temperature

No. stretch modulus I h high b . Id 15( > 50°/ ) Itorienta Line contact Point contact and shou d ave car on Yle /0 .tion. .may be added here that AN copolymer of intrin-

factor 108 mN 245 mN 108 mN 245 mN sic viscosity> 2.36 dlg-l is not recommended 'y1 2 x 0.6949 0.186 0.167 0.134 0.125 owing to poor spinnability and filtration ability,2 3 x 0.7316 0.221 0.183 0.135 0.127 while the copolymers with intrinsic viscosity3 4x 0.7556 0.230 0.202 0.136 0.128 < 1.25 dlg-1 yield fibres with poor mechanical4 5 x 0.17715 0.235 0.208 0.138 0.132 .5 6 x 0.78"47 0.238 0.211 0.138 0.137 propertIes.6 7x 0.7918 0.243 0.217 0.141 0.132 SAF spun from PAN homopolymer produce ~.poor quality of carbon fibres as compared to the

BAJAJ et al.: MODIFICATION OF ACRYLIC FIBRES 151

PAN PROCESS

PAN STABILIZATION CARBONIZE GRAPHITIZE

SPOOL EPOXY SIZING SURFACE TREATMENT

Fig. 3-Processing sequence for PAN precursor to carhonfibre

fibres spun from a ~opolymer of. AN containing Among the above-mentioned comonomers, ita-low percentage of comonomer96. The various conic acid seems to be superior for making acryl-comonomers used for synthesizing AN copolym- ic precursors for carbon fibres. The major reasoners suitable for producing acrylic precursor fibres for the superiority of itaconic acid over otherare: vinyl comonomers97 having acidic groups acidic comonomers is the presence of two carbox-such as acrylic acid (AA), methacrylic acid ylic groups in it. Considerable information exists(MAA) and itaconic acid98 (IA); esters such as in the lit6rature97 un the use of comonomers--methacrylate;

amide such as acrylamide; and am- (other than acidic) for controlling the heat fluxmonium sal~s of vinyl compounds such as quater- during stabilization of SAP. In the case of quar-nary ammoqium salts of aminoethyl-2-methyl ternary ammonium salts, a lowering in time ofpropionate. A combination of two comonomers stabilization, a reduction in the thermal degrada-has also been tried, e.g. methacrylic acid/methac- tion, and better control of heat flux during oxida-rylate and itaconic acid/methacrylate. tive cyclization have been reported99. Some minor

The role of comonomers, particularly acidic improvements in the dissipation of heat duringcomonomers, is well understood in the "most cru- stabilization in precursor fibres have also been re-cial step, i.e. thermo-oxidative stabilization of the ported through the use of hydrazine salts and ac-process during the production of carbon fi- rylamide99.bres.The heat evolved during stabilization of PANprecursors (SAP) in air atmosphere is quite high Carbon fibres are generally used as reinforcingand it might be detrimental to the properties of material for high performance composites, andcarbon fibre, if not dissipated/controlled efficient- thus carbon fibres with more surface area (nonly. Comonomers are. therefore, incorporated in circular) may have better adhesion with matrix.PAN for controlling this heat fl\lx. It has been es- The shape of the cross~section of carbon fibrestablished that acidic comonomers, if present in depends upon the shape of ptecursor, which maySAP, not only initiate the e~othermic cyclization be controlled easily depending on the cross-sec-reaction at a lower temperature, but also cause its tion of the spinnerette and coagulation bath con-propagation at a slower rate and thus help in ditions. Acrylic polymers tend to degrade well be-maintaining the heat flux. AN copolymers with low their melting point; hence, their melt spilHlingAA, MAA, IA and acrylamide with comparable is difficult. However, melt spinning of acrylic fi-COnIonomer content showed98 a drop in the tem- bres has been reported 100 by mixing the polymerperature of initiation of exothermic cyclization with propylene carbonate. The additives decreasereaction in stabilization process in the following the melting point of polymer through a plasticiz-order: ing effect? and thus avoid the complications of de-itaconic acid> methacrylic acid> acrylic acid gradation reactions that make melt spinning im-> acrylamide. possible.

152 INDIAN J. FIBRE TEXT. RES.,JUNE 1996

Asahi Chemical Co. Ltd 101 reported the melt 16 Sen K, Bahrami H & Bajaj P,J Macromol Sci, Rev Mac-

spinning of acrylic polymer containing water and ramal Chern Phys, C36( 1) (1996) 1-76.(PEG) b . I .17 JianG,JAppIPolymSci,44(6)(1992) 1095. ...

a water-soluble polymer to 0 taIn acry IC 18 Mi uaki S Hi hi o Shi S & y..I,'- Y rpn Pat ~.1()2 ts, royos ,geru IUAllI0, J.fibres of tenacIty 0.38 G~a. In ano~er pat~nt, 05, 209, 310 (to Mitsubishi Chern. Ind) 1993; Chernthe production of heat-resIstant acrylIc fibre IS de- Abstr, 120 (1994) 10301j.scribed by melt spinning of acrylic polymer at 19 Masahito o & Masashi A, Jpn Pat 05,272,015 (to Kane-230°C to give heat-resistant fibres of tenacity 0;25 bo Ltd) 1993; Chern Abstr, 120 (1994) 136985d.GP M . b. h. R C L"d 103 . d ' 20 InoueM, TextAsia,20(4)(1989)56.

a. ItSU IS I ayon q. t. In a patent IS. 21 B ..P S ta A K& J .n PC Text Res 1 50 ( 1980 )h I ..

f Ii aJaJ , engup ai, ,closed a process for t e me t spInnIng 0 acry c 218.fibres of tenacity 0.42 GPa. The acrylic polymer 22 ZakirovIZ,Khim Volokna,(I)(1980j15.was blended with another copolymer of similar 23 Yoshinori F & Yoshihiro N, Jpn Pat 05. 33. 213 (to .constitution but of low molecular weight (Mw Mitsubishi Rayon Co.) 1993; Chem'Abstr, 119 (1993)~ 4800) ~d extruded through a 72 hole spinner- 24 ~:~~~kH W & Morgenstern B, Melliand Textilber, 72

ette at 215 C. (6)(1991)399. JGrove et Oz.t°4 investigated the structure and 25 Mamazhanov A A, Timoshina L V, Zakirov I Z, Ergash- ,.,.

mechanical properties of melt-spun water-plasti- evKE&AskarovMA, Khim Volokna,(4)(1990) 22.cised PAN-based precursor. The morphology of 26 Kuznetsova L K, Brusentsova V G, Zver~v M P'iBarashthese fibres is reported .to be similar to that of ~~2f~~~kin V E & Kalyanova N F, Khlm Volofcna, (4)

wet- and dry-spun acrylic fibres. However, there 27 Minoru S & Masahito 0, Jpn Pat 05, 302, 213 (towere more surface defects and internal voids in Kanebo Ltd) 1993; ChemAbstr, 120 (1994) 247308e.the melt-spun water-plasticized fibres than in the 28 Hiroaki N, Kazuo N, Mitsuhiro M, Masaaki T & Hiro-wet- or dry-spun ones. In a Japanese patent99, the bumi 0, Jpn Pat 05, 117,912 (to Mitsubishi Rayon Co.).. I " 1 h b 1993; Chern Abstr, 119 (1994) 205410f.me!t SpInnIng of polya~ry omtn e. as een 29 Yasuo Y, Fumio T & Taku T, Jpn Pat 03', 234, 807 (toclaImed to produce acrylIc fibre WIth 5.2 gpd Mitsubishi Rayon Co.) 1991; Chern Abstr, 116 (1992)

(0.46 GPa) tenacity. 61487x.Atureliye and Bashirlos. melt-spun polyacryloni- 30 Jun Y, Toshiaki H, Haruo 0, AJ:ira I & Hideo S, Jpn

trile plasticized by propylene carbonate and ob- Pat 5, 195, 313 (to Toray Industnes) 1993; Chern Abstr," f'

h fil 120(1994)109386c. served that X-ray dIffractIon pattern 0 t e a- 31 v hik M "T'_I, h. M Sh ,. T H.k Y & S t ok o ~ .

f I I .. 1 IOS atsu ,IilAaS I , uJi , Iro 0 a

ments was dIfferent from that 0 po yacry omtn e K, Jpn Pat 04,361,614 (to Kanebo Ltd) 1992; Chernpowder; however, these melt-spun filaments on Abstr, 118 (1993) 214807x.drawing led to normal hexagonal polymorph. The 32 Yasuo Y, Fumio T, Akemi K & Yoshinori F, !pn Pat 04,plasticized melt of polyacrylonitrile has shown 272, 220 (to Mitsubishi Rayon Co.) 1992; Chern Abstr,h -hi ' b h vi r 118(1993) 23690u.

sear t nmng e a ou. 33 Zeming L, Development & application of new acrylic fi-

bre, paper presented at 2nd Int.Conf. on Man-made Fi-References bres, Beijing, 26-29 November 1987.

34 BajajP,MelliandTextilber,76(4 )(1995)E52.1 Anon, Text Month, (5) 199~J39.. 35 Kravchuk V M, Zgibneva Zh A, Milyavskaya I Kh, Er-2 Anon, Man-made Text India, 38(11)(1995)457. gashev K E & Zakirov I Z, Khim Volokna, (1) (1989)3 Kinep E, Chemiefasem/l'ext-Ind, 38/90 (1988) T116. 10.4 Masson J C, Acrylic fibre technology and application, 36 Brown D M & Pailthorpe M T, Rev Prog Color, 16

edited by J C Masson (Marcel Dekker, New York), (1986) 8. -., 1995,341. 37 Hide-to D, Koji N & HiroyukiK, Jpn Pat 06,228, 812

5 Hahne M & Schuster U~ Tech Text (Text Horizons (to Mitsubishi Rayon Co.) 1994; Chern Abstr, 122Supp/), (March 1990)'6. (1995) 83595j.

6 SchummC, Tinctoria, 88 (7)(1991) 71. 38 Akio T & Mitsuaki S, Jpn Pat 04, 245, 971 (to Mitsub-7 Romano"a E P, Gorodetskaya N A, Pantsova 1 I, Kli- ishi Rayon Co. Ltd) 1991; Chern Abstr, 118 (1993)

menko I B, Vol'f L A, Firsov E I & Emets L V, Khim 126448a.Volokna, (6) (1981) 43. 39 Wenjie S, Dangdong M & X1n~en C,Chem Abstr, 122

8 JohnsonDJ, Text Month, (10)(1989) 55. (1995) 163424t.9 Fitzer E, Carbon, 27 (1989) 621. 40 Viera 1\, Stofan T..Peter D, Milan D, Dusan B, Eva C,

10 BashirZ, Carbon, 29(8)(1991) 1081. Eva S & Milan H, Czech Pat 270,112 (1991); Chern11 MachaieidtM, Text Technik, 40(3)(1990) 158. Abstr, 110 (1992) 22839w.12 Rajalingam P & Radhakrishnan G, J Macromol Sci, Rev 41 Sen K, Bajaj P & Rameshbapu J S, Melliand Textilber, Y

Macromol Chern Phys, C31 (2 & 3)(1991) 301. 72(12) (1991) E416/1034.13 Bajaj P & Surya Kumari M, .J Macromol Sci, Rev Mac- 42 Abdurakhmanova Sh'(], Dzhalilov Sh S & Anosov V P.

romoIChemPhys,C27(2)(1987) 181. Khim Volokna, (5)(1989) 35.14 Nogaj A, ChemiefasemlText-lnd, 36/88 (1986) EIOI. 43 Artemenko S E, Nikulina L P, Ustinova T P,Akbarov D15 Bajaj P & Paliwal D K, Indian J Fibre Text'Res, 16(3) N, Krainov E P & Dubkova V 1, Khim Volokna, (4)

(1991) 89. (1992) 39.

BAJAJ et al;: MODIFICAll0N OF ACRYUC FmRES- 153

44 Yoshihiro I. Shogo H, Jpn Pat 62,231,080 (to Toray In- 72 Yoji M, Tomihiro I & Toru H, Jpn Pat 03, 241, 015 (todustries Inc.) 1987; Chern Abstr, 108 (1988) 152106a. TorayIndustries) 1991; ChemAbstr, 116 (1992) 61474t.

45 Peskova V I, Beder N M, Kukushkina S A, Konovalov A 73 Hiroaki 0, Yasuo Y, Kazuo N & Mitsuhiro M, Jpn PatV, Kurupinova M I & Oigor'eva L N, Khim Volokna, 05, 222, 608 (to Mitsubishi Rayon Co.) 1993; Chern(5) (1987) 27. Abstr, 120 (1994) 10303m.

46 Minami T, Proceedings, 8th International Wool Textile 74 Juchi F, Shigeki H, Shofi H & Hideaki H, Jpn P~,Research C.onference, edited by G H Crawshaw, 1990; 257, 009 (to Mitsubishi Rayon Co.) 1994; CMm Abstr,Chern Abstr, 118 (1993) 170907y. 122 (1995) 83597m.

47 Romanova E P, Gorodetskaya N A, Pantsova I I, Klimenku 75 Wolfgang A, Volker G, Paul K, Werner M, Dieter P,I B, Vol'f LA, Firsov E 1& Emets L V, Khim Volokna, (6) Thomas W, Manfred H & Klaus M, Ger Offen DE 4,(1981)43. 021, 052 (to Akademie der Wissenschaften del DDR)

48 GellerG,Khim Volokna,(3)(1979) 19. 1992; ChemAbstr, 116(1992) 153477z.49 Yoshikatsu M, Kazumi W, Shuji T & Hiroko T, Jpn Pat 76 Todorova I, Karkinska M, Rizovska V & Andreevski B,

04,333,611 (to Kanebo Ltd) 1992; Chern Abstr, 118 MelliandTextilber, 73 (1992)E317. ,(1993) ~14814x. 77 Tedesco R & Mangerrari A, High modulus polyacryloni-

50 Mas~ S & Masayasu H, Jpn Pat Os., 86, 575 (to Toyo trile fibres-Ricem, paper presented at the 2nd InternationalBoseki) 1993; ChemAbstr, 119 (1993) 182783p. Conference on Man-made Fibres held at Beijing China

51 Minoru S, Masakito 0 & Masashi A, Jpn Pat 05,321, 26-29 Nov. 1987. ' ,

030 (to Kanebo Ltd) 1993; Chern Abstr, 121 (1994) 1M Yoshiyuki f, Hiroshi T & Fujo U, Jpn Pat 02, 210, 062

11.646~... ( ) (to Toray Industries, Inc.) 1990; Chern Abstr, 114 (1991)52 Hiroshi N & Setsu)1 E, Jpn Pat 06, 25, 980 1994 64206b.

11650e: .79 Yoshinori F & Yoshihiro N, Jpn Pat 04, 245, 913 & Jpn53 Masashil A & Masahito O,_Jpn ]!a!05, 272, 008 -(to I Pat 04, 245, 914 (to Mitsubislii Rayon Co.' Ltd) 1992;Kanebo Ltd) 1993; ChemAbstr, 120 (1994) 136982a. ChemAbstl: 118 (1993) 8263p and 8264q -

54 Masanori A, Satoru T, Hiroshi o & ~unio I, Jpn Pat ..'.07, 119, 037 (to Mitsubishi Rayon eo.) 1995; Chern 80 Ken)l. K & Yutaku N, Jpn Pat 06,57,524 (tQ Toray In-Abstr, 123 {1995) 172562j: dustnes) 1994; C~em Abstr, 121 (1994) 37556d.

55 Tokahiro -0, Shinichi H, NODUyuki N & Kanji T, Jpn Pat M I Sadam M & Akltaka K, Jpn Pat 06, 25, 910 (to Asahi62, 263, 311 (to Kanegafuchi Chemical Industry Co. Chemical Ind.) 1994; Chern Abstr, 120 (1994) 301040b.Ltd) 1987; Chern Abstr, 108 (1988) 152065m. 82 Atsushi N, Eiichi H, Michisuke E, Hiroaki Y & Toshihi-

56 Minoru S & Toshihiro Y, Jpn Pat 63~ 12,722 (to Kanebo r.o M. Jpn Pat 05, 44, 132 (to Mitsubishi Rayon) 1993;Ltd) 1988; ChemAbstr, 108 (1988) 152068g. C-nem Abstr, 118 (1993) 2S6556v.

57 Etsoshi N, Takashi H, Toshiaki E & Kenichiro C, Jpn Pat 83 Yasushi M & Shigemi Y, Jpn Pat OS, OS, 224 (to Asahi04, 114, 018 (to Kanegafuchi Chemical Industry Co. Chemical Ind.) 1993; Chern Abstr, 118 (1993) 235876j.Ltd) 1992; ChemAbstr, 117 (1992) 132835v. R4 Mikolajczyk T, Krucinska I & Kameeka-Jedrzefezak K

58 Yoshihiro M & Seizo 0, 06, 306, 706 (to Mitsubishi Ray- Polymery 34 (5) (1989) 213.on Co.) 1994; ChemAbstr, 122(1995) 190265y. 85 Padhye M R& Karandikar A V, J Appl Polym Sci, 33

59 Bajaj P & Padmanaban M, Indian J Text Res, 10 (1985) (1987) 1675.1. 86 Gupta B S, EI-Mogahzy Y E & Selivansky D, J Appl

60 Kazuhiro S & Kazumi W, Jpn Pat 04, 194, 018 (to Polym Sci, 38 (1989) 899.KaneboLtd) 1992; ChemAbstr, 118 (1993}40763n. 87 East G C, McIntyre J E & Patel G C, J Text Inst, 3

61 Hiroaki N, Kazuo N, Taku T & Yoshihiko H, Jpn Pat (1984) 196.03, 174, 011 (to Mitsubishi Rayon) 1991; Chern Abstr, RR Baojan Q, Jian Q & Zhenlong Z, Text Asia, (April &115 (1991) 281979f. May 1989)48&30.

62 Masashi A & Kunioki Y, Jpn Pat 05, 163,625 (to Kane- 89 Mitsubishi Rayon Co. Ltd, Jpn Pat I, 104, 816 (1989);boLtd) 1993; ChemAbstr, 120 (1994) 166691x. ChemAbstr; 111 (1990) 155230.

63 Hideki M & Tadao K, Jpn Pat 05, 279, 915 I,to Mitsub- ..ishi Rayon Co.) 1993; Chern Abstr, 120 (1994) 90 Donnet J B & Bansal R C, Carbon fibres, 2nd edition166700 (Marcel Dekker Inc., New York) 1990.

64 TsaiJ,J~aterSci, 28 (1993) 1161'. 91 Peebles.L H (Jr), Carbon fibres: F~rmation, strncture & I65 Takahi o Shini hi H N b aki N & K ..T J: R t propel1l.es, Chap. 3 (CRC Press, Flonda, USA) 1995.ro, C , 0 u~ .an)1 , pn 1I 92 FitzerE&FrohsW, ChemEngTechno~ 13 (1990} 41.

62, 263, 312 (to Kanegafuchi Chemical Industry Co. 93 D nh M G & Ed. D D C b 30(1992)435Ltd) 1987; ChemAbstr, 108 (1988) 152064k. ~ am .Ie '. a~ on, ..66 Ba.a. P & SeD ta A K Text Pro 22 (2/3/4) (1992} 94 Jal?~K&AbhlramanAS,JMatScI,22(19.87)278.

21~ ~ gup , g, 95 Ba)a) P & RooP8?wal A K, J Macromol SCI, Rev MacrQ-

67 Ko T H, J Appl Polym Sci, 43 (1991) 589. mol Chern Phys, (m pr~).

68 Masashi A & Kunioki Y, Jpn Pat 04, 316, 616 (to Kane- 96 MullerT,lntFibreJ,3(1988)46.bo Ltd) 1992; ChemAbstf, 118 (1993) 214846j. 97 Roopanwal A K, Effect of comonomers and chemical

69 Zhang J, Horrocks A R & Hall M E, Fire Materials, 18 pretreatments on the thernlQ-oxidative stabilization of a(~(1994) 307. rylic precursors and resulting carbon fibres, Ph. 0. thesis,

70 Yoji M, Katsumi Y & Toru H, Jpn Pat 03, 241, 005 (to Indian Institute of Technology, Delhi, 1993.Toray Industries, Inc.) 1991; Chern Abstr, 116 (1992) 911 Klimeuko I B, Platonova N V, Tarakanov B M & Maib-61470p. urov S P, Khim Volokna, (6) (1993) 20; Chern Abstr,

71 Hidehiro S, Masahiro H & Toshio Y, Jpn Pat 06,65, 120(1994) 193912b.809 (to Toray Industries) 1991; Chern Abstr, 121 (1994) 99 Gupta A K, Paliwal D K & Bajaj p, J Macromol Sci. .-37560m. Rev,C31 (1991) I. _11-

154 INDIAN J. FIBRE TEXT. RES., JUNE 1996

100 Bashir Z,J Polym ~'ci(Polym Phys), 30 (1992) 1299. 103 Mitsubishi Rayon Co. Ltd, Jpn PfJt 62,268,812 (1987);101 ASahi Chemical Industry Co. Ltd., Jpn Pat 60, 94, 215 Chem Abstr. 108(18) (1988) 79.152070.

(1985); ChemAbstr.l03(12)(1985)61.89014. 104, Grove D. Desai P & Abhiraman A S. (.urboll. 26 (3) ~102 Mitsubishi Rayon Co. Ltd, Jpn Pat 62, 149,918 (1987); ('988)403.

ChefnAbstr, 108(8) (1988) 82, 57798. 105 Atureliya S K & BashirZ. Polymer. 34 (24) (1993) 5116.

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