Indian Journal of Fibre & Textile ResearchVol. 19, December 1994, pp. 277-285

Effect of selective pretreatments and different resin post-treatmentson jute-viscose upholstery fabric

P Ghosh, A K Sarnanta" & D Das·

Department of Plastics & Rubber Technology, Calcutta University,92 Acharya Prafulla Chandra Road, Calcutta 700009. India

Received 24 June 1993; revised received 8 November 1993; accepted 29 November 1993

The effects of selective chemical pretreatments imparting texturing and bleaching separately andsequentially on 60 ; 40 jute-viscose fabrics have been studied. It is observed that sequential texturingand bleaching treatments impart certain desirable property benefits over that imparted by only text-uring or bleaching, particularly in respect of crease recovery, breaking extension, whiteness andbrightness index, with marginal drop in tenacity. Post-treatments with urea-formaldehyde (UF), di-methyloldihydroxyethylene urea (DMDHEU), butylated urea formaldehyde (BUF) or acrylamideformaldehyde (AMF) of sequentially pretreated fabric further reduce tenacity to the extent of 5-27%;the order of tenacity drop on resin finish being UF> DMDHEU > BUF> AMF. AMF resin finishresults in substantial increase in the moisture regain of the pretreated fabric, while other resin fin-ishes lead to lowering of moisture regain. With respect to improvement in crease recovery the differ-ent resins stand in the order DMDHEU = AMF> UF> BUF. Considering resin uptake, crease re-covery, abrasion resistance, moisture regain, tensile properties and fabric stiffness, AMF resin finishrendered 60 ; 40 jute-viscose fabrics notably better suited for upholstery application.

Keywords: Abrasion resistance, Crease recovery, Jute-viscose fabric, Resin finish, Texturing,Upholstery fabric

I IntroductionJute fibre has some inherent advantages for its

agro-origin, cheapness, high moisture regain, goodtensile strength and biodegradability. Still, notabledisadvantages for jute fabric lie in its coarseness,surface fuzziness (yam hairiness), fibre shedding,low extensibility, poor washability, yellowing orbrowning under sunlight, poor drape consequentto high stiffness, and poor crease recovery pro-perties. A solution to minimize the disadvantagesmay partly be found through blending jute withother finer fibres such as viscose, polyester andpolypropylene and partly by subjecting the blendsto suitable chemical pretreatments'F and resinfinishes.

Jute-viscose blends are gaining popularity forupholstery and related applications. Technical de-velopments and standardization of these productshave yet to take place to full potential. Jute-vis-cose fabrics have attractive appearance but theirwrinkle recovery and drape are less than adequ-ate for upholstery and related applications, leav-

'Institute of Jute Technology, Calcutta University,35 BaJlygunj Circular Road, Calcutta 700 019, India

ing ample scope for improvement. A good degreeof fibre shedding still remains a disadvantage fOIthis blend.

Chemical treatments of jute and jute blendedyams and of 100% regular viscose':" using up to22% NaOH are reported. H202 bleaching of juteand viscose has also been studied in detail>",Considerable work has been done" on N-methyl-olated resin finishing of cotton cellulose and ray-on (regenerated cellulose). But reports on resin!polymer finish of jute blends, including jute-vis-cose blends, are scantyf-!" even though such stud-ies with jute have been made!"!". While studyingthe pretreatments of jute fabric prior to resin fin-ishing, some workers'S" used up to 9-10%NaOH on bleached jute fabric. But such low-to-moderate alkali treatment of jute does not resultin shrinkage and crimp high enough to make thefabric adequately suited for crease-resistant fini-shes in a subsequent step.

The present work is aimed at (i) improvingdrape by reducing stiffness through selective pre-treatments of 60 : 40 jute-viscose fabric by chemi-cal texturing'< using 18% NaOH and by bleach-ing"? using 4% H202 separately or sequentially

278 INDIAN J. FIBRE TEXT. RES., DECEMBER 1994

for different durations, and (ii) improving creaserecovery and surface character by selected resinpost-treatments keeping in view the latest de-mands of upholstery application.

2 Materials and Methods2.1 Materials2.1.1 Fabric

Grey 60: 40 jute-viscose fabric having the fol-lowing specifications was used: Weave-plain;Weight-307 g/rn"; Picks/dm-72; Ends/dm-60;Warp count-140 tex; and Weft count-160 tex.

2.1.2 ChemicalsCommercial sodium hydroxide, sodium silicate,

acetic acid and 30% hydrogen peroxide, and LRgrade boric acid, sodium metaborate, 40% for-maldehyde, acrylamide, potassium persulphateand magnesium chloride were used.

2.1.3 ResinsTextile grade 1,3-dimethylol-4,S-dihydroxy-

ethylene urea (DMDHEU) obtained from AhuraChemicals (Ahuramine-YX with SO% solid con-tent) was used.

Aqueous urea-formaldehyde (UF) resin, i.e.mixed methylol urea (S8% solid content), wasprepared in the laboratory by the usual method/".

Water insoluble butylated urea-formaldehyde(BUF) resin (S6% solid content) obtained from alocal manufacturer was used in an emulsion form.The resin was partly diluted in 1 : 1 xyleneibuta-nol mixture and then emulsified in water contain-ing a non-ionic emulsifier (O.S%), giving a solidcontent of 10% for the emulsion.

A water soluble vinyl monomer precondens-ate-methylol acrylamide resin (AMF) with 24%solid content-prepared in our laboratory" bycontrolled alkali (NaOH)-catalyzed condensationof acrylaniide and neutralized formaldehyde wasused.

2.2 Methods2.2.1 Chemical Texturing

60 :40 Jute-viscose fabric of a suitable size wasdipped in a stainless steel bath containing aque-ous 18% (w/w) sodium hydroxide solution, keep-ing the material-to-liquor ratio at 1 : 10 (w/v) for1 h at room temperature I (25 ± 2°C). Thereafter,the fabric was washed tho toughly first with satu-rated brine solution" and then with hot water",considering the presence of viscose in the blend.as well as also neutralized with 1% commercial gradeacetic acid solution, rinsed with water and driedin air. 18% NaOH treatment produces chemical

texturing+? on jute part and slack mercerization"on viscose part.

2.2.2 BleachingThe jute-viscose fabric was scoured 14 with 2%

(owf) sodium carbonate solution and 1 gIl non-ionic detergent by heating at 80°C for 30 min us-ing fabric-to-liquor ratio of 1 :S (w/v). Bleachingwith H202 was perforrned=t-'? on the scoured fa-bric in a laboratory jigger using appropriate vo-lume of commercial H202 to give 4% (owf) H202(SO%) in the bleaching bath, where the pH wascontrolled between 8 and 8.S considering thepresence of viscose in the fabric. After bleachingfor 30 min or 1 h at 80°C, the fabric was washedwith water, neutralized with dil. acetic acid,washed again with water and dried.

2.2.3 Sequential Texturing and BleachingJute-viscose fabric samples were also subjected

to sequential chemical texturing and bleaching, i.e.parts of the washed textured fabric samples wereimmediately subjected to bleaching. For the se-quential treatment, time periods for successivetexturing and bleaching were kept at 30 min eachor 60 min each.

2.2.4 Resin Post-treatments10% aqueous solution or emulsion of each resin

(DMDHEU, UF, BUF and AMF) containing 2%MgCl2 as curing catalyst23,27,30 was taken forpadding the pretreated fabric, The padding wasperformed in Lab-2-bowl padding mangle (twodip-two nip) at an expression or wet pick-up of80% to maintain in each case 8% resin applica-tion on the weight of fabric. The fabric was par-tially dried thereafter at 80°C for 10 min in a labstenter and immediately subjected to resin cure"at 150°C for 4 min. Finally, the fabric was cooled,soap washed following ISO-II method-", furtherwashed with water and dried in air. To effectpolymerization of AMF resin selectively throughthe vinyl unsaturation, the fabric w8f>presoakedin 0.5% K2S20g solution before AMF resin appli-cation as above. The hydrophobic character ofthe cured resins is in the orderBUF~ UF> DMDHEU ~ AMF. AMF resin,much alike polyacrylamide, is hydrophilic in- na-ture.

2.2.5 Determination or Moisture Regain andNitrogen Content

Moisture regain values of the fabrics were de-termined by the oven drying method-? followingASTM-629-S9T method. Nitrogen contents of se-

GHOSH et al.: JUTE-VISCOSE UPHOLJTERY FABRIC

lected untreated and treated fabrics were deter-mined by the Kjeldahl method.

2.2.6 Measurement of Tensile PropertiesFabric tenacity, breaking extension and modu-

lus corresponding to 1% extension (initial modu-Ius) of selected treated/untreated jute-viscose fa-bric samples were measured as per IS: 1969-1968(ref. 22) in Zwick-1445 CRT universal tensiletesting machine. The average of 10 tests in warpdirection was taken for each sample tested underthe following conditions: Clamping test strip spec-imen ravelled to a specific sample size(50 mm x 20 mm) between the two jaws of thetensile testing machine; Traverse speed, 100 mm/min; and pretension level, 0.2 N.

2.2.7 Measurement of ShrinkageDifferent jute-viscose fabric samples were sub-

jected to washing as per ISO-II (5 g/l soap, 50°C,45 min) in a Sasmira Launder-o-meter. Shrinkageon wash was measured as per IS: 2977-1964 (ref.22). Shrinkage on chemical treatments was mea-sured in the same way after each pre- and post-treatment completed with necessary rinsing, wash-ing and drying.

2.2.8 Measurement of Stiffness (Bending length)Fabric stiffness, as expressed by bending length,

was measured as per IS: 6490-1971 (cantilevertest)22 in a Sasmira stiffness tester with specimensize of 25 mm x 200 mm.

2.2.9 Determination of Abrasion ResistanceComparative evaluation of accelerated flat abra-

sion resistance of selected fabrics was done in anelectronic abrading instrument (crockmeter) using astandard (IS-715) paper abrader for a specificwear following the principle described inAATCC-93-974. The abrasion resistance of se-lected fabric samples was given by digital displayof the number of cycles of accelerated flat abra-sion corresponding to appearance of specified na-ture of wear (first appearance of hole on the fa-bric by wear and tear of the yams).

2.2.10 Measurement of Crease Recovery AngleThe dry crease recovery angle of selected fabric

samples was measured using a Sasmira crease re-covery tester in accordance with ASlM-D 1295-67.

279

2.2.11 Measurement o(Whiteness Index andBrightneSf Index

Whiteness index was measured by Hunter labscale" using 2020-plus Macbeth reflectance spec-trophotometer. Brightness index for jute goodswas measured using standard precedure as the ra-tio of reflectance of jute fabric at a particularwavelength (420 urn) and reflectance of a stand-ard glazed white tile (using a reference materialwith a reflectance of 100%) at the same wavelength, expressed in percentage. Reflectance wasalso measured using the 2020-plus Macbeth ref-lectance spectrophotometer.

3 Results and DiscussionThe results are presented under two heads:

-showing how selected pretreatments of thechosen jute-viscose fabric make it more worthyfor DMDHEU resin post-treatment and howdifferent sequences of pretreatment and post-treatment result in different degrees of improve-ment or change in textile related properties ofthe fabric; and'

-showing how resin finish of the optimally pre-treated fabric using different methylolated res-ins/resin derivatives make them differently suit-ed as upholstery fabric with desirable balanceof drapable character (low stiffness), crease re-covery (high crease recovery angle) with opti-mum resilience and extensibility, comfort andfeel (high moisture regain), durability (good de-gree of tenacity retention and abrasion resist-ance) and dimensional stability (low wash shrin-kage).

3.1 Effect of Different Pretreatments andSubsequent DMDHEU Resin Post-treatment

Resin treatment usually increases the stiffnessof cotton and related fabrics, impairs theirdrape28.18 and causes noticeable loss in tenacityand abrasion resistance. To keep the stiffness en-hancement to a bare minimum and to improvethe extensibility, adoption of selective pretreat-ments2.4.5.7.15 prior to controlled resin applicationoq the 60: 40 jute-viscose fabric was considerednecessary and for this DMDHEU resin was selec-ted for preliminary studies.

3.1.1 Tensile PropertiesTenacity, breaking extension and initial modu-

lus of untreated and pretreated 60: 40 jute-vis-cose fabrics as well as the weight loss associatedwith each pretreatment are shown in Table 1.

280 INDIAN J. FffiRE TEXT. RES., DECEMBER 1994

Table 1- Effect of selective pretreatments and DMDHEU post-treatment on tensile andother properties of 60 : 40 jute-viscose fabric

Pretreatment Weight loss Hunter lab Brightness Tenacity Breaking Modulus at% whiteness index N/mm extension 1% extension

index % N/mm

None (untreated) 60.7 23.3 10.56 7.42 22.56

(8.80) (4.84) (45.26)18% (w/.w) NaOH (texturing) 10.32 53.8 11.5 10.04 28.66 4.26

at room temp. for 1 h (8.60) (19.62) (8.92)18% (w/w) NaOH (texturing) 9.02 58.2 17.9 10.49 25.52 4.36

at room temp. for 30 min (8.95) (16.50) (9.20)4% (owf) H202 (bleaching) 8.20 74.6 49.7 8.65 18.27 4.43

at 80°C for 1 h (7.14) (13.37) (10.40)4% (owf) H202 (bleaching) 6.70 72.3 49.4 1O.ot 19.06 4.49

at 80°C for 30 min (8.12) (14.23) (10.70)18% NaOH for 1 h followed 20.80 64.4 29.9 8.16 27.22 4.13

by 4% H202 bleach for 1 h (6.96) (18.74) (8.80)18% NaOH for 30 min followed 16.02 71.4 40.9 8.98 24.90 4.24

by 4% H202 bleach for 30 min (7.85) (16.89) (9.40)

The values in parentheses indicate the corresponding property data for the respective fabric obtained after 8% DMDHEUresin post-treatment.50%.H202 (4% owf) was used.

3.1.1.1 TeueityThe pretreatment processes are associated with

different extents of drop in tenacity and loss inweight (Table 1). The sequential texturing andbleaching pretreatments, each for 1 h, expec-tedly2,4,6,7 lead to higher overall weight loss andsomewhat higher drop in fabric tenacity associat-ed with degradative action of NaOH on both juteand viscose part for long duration. Sequentialtexturing and bleaching, each for 30 min, how-ever, produce an improved balanced effect, show-ing high retention of tenacity of the treated fabricsdespite moderate weight loss. Discussion in sec-tions 3.1.2 and 3.1.3 (last para) will further sub-stantiate the observed effects considering dura-tion of each treatment, where chemical texturingis associated with opposing influences of massloss and high shrinkage level mainly in jute partand slack mercerization effect on viscose part andH202 bleaching of jute-viscose fabric for 30 mininstead of 1 h render more protection of jute andweaker yiscose component from oxidative degrad-ation.

DMDHEU resin post-treatment leads to furtherlowering of tenacity for both untreated and pre-treated jute-viscose fabric, the effect being gener-ally higher for the sequentially pretreated fabric(Table 1). However, the strength retained after the

pretreatments is within the acceptable limit ofspecification for cotton upholstery (sheetings/fur-nishingsf".

3.1.1.2 Breaking Extension and Initial ModulusBreaking extension for the jute-viscose fabric

increases significantly after each pretreatment, butit suffers some reduction in its enhanced value onDMDHEU resin post-treatment. Treatment with18% NaOH at room temperature for 30-60 minapparently produces a good texturing effect givingbreaking extension as high as 25-28% whichdrops to 16-20% on DMDHEU resin post-treat-ment. Texturing effect (resiliency and stretchabil-ity) or increase in breaking extension is substan-tially low when the fabric is simply subjected tobleaching pretreatment. Texturing effect was verypoor for NaOH concentrations <t 18%. OnDMDHEU resin post-treatment, breaking exten-sion reduces for all the pretreatments; this isthought to arise as a consequence of crosslinksestablished in the cellulosic chains through thechemically linked resin moieties.

Initial modulus gets drastically reduced on allpretreatments. Post-treatment with DMDHEUresin helps to regain part of the lost modulus ofeach pretreated fabric in much the same manneras observed for the resin treatment of the untreat-ed fabric. In each case, there is nearly or a little

GHOSH et al: JUTE-VISCOSE UPHOLSTERY FABRIC

more than two-fold increase in modulus of the re-spective fabric on DMDHEU resin treatment(Table 1).

3.1.1.3 Stiffness

Drapability of a fabric can be judged by itsstiffness; lower stiffness corresponding to higherdrapability. Stiffness values of fabrics (expressedin terms of bending length in Table 2) get reducedon texturinglbleaching pretreatment . ControlledDMDHEU resin post-treatment, however, causesmoderate to substantial regain of the lost stiffness.The stiffness regain is comparatively high forDMDHEU resin post-treatment when the substr-ate fabric is subjected to sequential pretreatments(Table 2).

3.1.2 Whiteness and Brightness IndicesIt is clearly revealed from data in Table 1 that

much alike jute fabric=", simple texturing of thejute-viscose fabric using 18% NaOH lowers itswhiteness and brightness indices substantiallywhile bleaching process contributes to their not-able improvement, as expected-". Sequential text-uring and bleaching treatment, however, offers anoverall balance of properties considering white-nesslbrightness index, tenacity retention andbreaking extension, particularly if the sequentialtreatments are performed for 30 min each insteadof 1 h under prescribed conditions.

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3.1.3 Crease Recovery AngleTable 2 shows that the (warp +weft) dry crease

recovery (CR) angles of the jute-viscose fabric arereduced on all pretreatments, the lowering effectbeing slightly more pronounced for alkali pre-treatments for texturing. The measured CR anglesare of the lowest order for sequentially texturedand bleached samples when compared with thosefor corresponding fabrics separately textured orbleached. In each case, post-treatment usingDMDHEU makes the respective pretreated fabricsamples gain substantially in CR angle, the percent gain being of the order of 15% for untreated,35-40% for textured (18% NaOH) and 50-53%for bleached [50% H202 (4% owf)] and about 70-75% for sequentially textured and bleached sam-ples.

The order of improvement in CR angle(Table 2) is in tune with the order of DMDHEUresin uptake of the blended fabrics pretreated dif-ferently as revealed by N 2 content data (Table 3).Higher resin uptake under comparable conditionsultimately results in higher degree of crosslink-ing3,14.28 of the fibre components in the fabric,causing higher rise in stiffness and CR angle(Tables 2 and 3). The drop in CR angle of jute-viscose fabric on the given pretreatment resultslargely from weight loss to the extent of 7-20%(Table 2) and partly as a consequence of associat-ed oxidative/hydrolytic degradation depending on

Table 2-Effect of selective pretreatment and DMDHEU resin post-treatment on dry crease recovery, abrasionresistance and stiffness of 60 : 40 jute-viscose fabric

Pretreatment Dry crease recovery Abrasion resistance Bending lengthangle (warp +weft) (No. of cycles to a specific em

deg wear)

a b a b a b

None (untreated) 163 188 77 59 3.6 4.618% (w/w) NaOH (texturing) 142 200 58 41 3.3 3.9

at room temp. for 1 h18% (w/w) NaOH (texturing) 140 189 49 37 3.0 3.8

at room temp. for 30 min4% (owf) H202 (bleaching) 144 218 40 31 2.1 2.9

at SO·C for 1 h4% (owf) H202 (bleaching) 150 225 45 35 2.5 3.4

at 80·C for 30 min18% NaOH for 1 h followed 138 240 53 42 2.8 4.1

by 4% H202 bleach for 1 h18% NaOH for 30 min followed 134 235 46 37 2.7 4.0

by4% H202 bleach for 30 min

a-Before resin finishb-After resin finish (8% DMDHEU)SQ% HiOz (4% owf) was used.

282 INDIAN J. FmRE TEXT. RES., DECEMBER 1994

Table 3-Shrinkage values (on pretreatment and on wash) and nitrogen contents of selectively pretreated andDMDHEU resin post-treated 60 : 40 jute-viscose fabric

Pretreatment Shrinkage on treatment Shrinkage on wash (ISO-II) Nitrogen content% % %

Warp Weft Warp Weft

None (untreated) 9.8 9.0 0.11(2.63) (2.15) (0.59)

18% (w/w) NaOH (texturing) 27.5 26.0 0.85 0.82 0.17at room temp. for 1 h (0.75) (0.50) (0.74)

18% (w/w) NaOH (texturing) 20.0 15.0 2.02 1.92 0.16at room temp. for 30 min (1.64) (1.12) (0.79)

4% (owf) H202 (bleaching) 10.0 7.09 7.2 8.0 0.12at 80°C for 1 h (2.12) (2.02) (0.89)

4% (owf) H202 (bleaching) 8.8 6.03 8.1 8.4 0.12at 'BO°Cfor 30 min (2.40) (2.10) (0.92)

18% NaOH for I h followed 24.61 20.0 0.84 0 0.13by 4% H202 bleach for 1 h (0.64) (0) (1.05)

18% NaOH for 30 min followed 25.37 18.25 1.60 1.33 0.10by 4% H202 bleach for 30 min (0.84) (0.40) (1.10)

The values in parentheses indicate the corresponding data for the respective fabric after 8% DMDHEU resin post-treatment50% H202 (4% owf) was used

the nature/duration of pretreatment. Simple text-uring and sequential texturing and bleaching pre-treatments result in relatively high shrinkage andthe tenacity loss/retention and the CR angle ob-served must be viewed as a consequence of theopposing influences of weight loss effected andshrinkage level imparted.

3.1.4 Abrasion ResistanceMuch alike jute fabric!", abrasion resistance of

the jute-viscose fabric also drops substantially oneach pretreatment (Table 2) as a consequence ofweight loss and weakening of the fabric.DMDHEU resin post-treatment causes furtherdrop in abrasion resistance much as a consequ-ence of stiffening effect imparted by the incorpo-rated resinll•13,18. The drop in abrasion resistanceis comparatively high for bleaching treatment thanfur texturing (high stretchability and high-shrunkfabric can resist more abrasion) in view of moresevere oxidative weakening of the fabric onbleaching.

3.1.5 ShrinkageJute-viscose (60: 40) fabric suffers different de-

grees of shrinkage in warp and weft directions+"011 either texturing or bleaching, the shrinkage be-ing more in case of texturing (Table 3). It is some-what surprising that sequential texturing andbleaching for an extended period (1 h each) re-

sults in a level of shrinkage that is measurablylower than what is expected from the texturingpretreatment alone for 1 h. The texturing appar-ently causes the fabric to reach its maximumshrinkage potential (27% shrinkage) with high ret-ention of tenacity, and subsequent bleaching cancause practically no further shrinkage. However, agood deal of further weight loss on subsequentbleaching in the said sequential process makes theyams or fibres in the fabric finer which may resultin some expansion effect, causing some dimen-sional relaxation of the fabric, particularly in thewarp direction; this is evidenced by the two-stepshrinkage data for sequential texturing andbleaching (1 h each) (Table 3).

Resistance to shrinkage on washing?" is muchimproved on texturing than on bleaching. Thewash shrinkage resistance or dimensional stabilityof the fabric is still better if it undergoes sequen-tial texturing and bleaching.

DMDHEU resin post-treatmenf makes all thepretreated fabrics show a high shinkage resistanceon washing, more so for sequentially textured andbleached samples. Resin finish on the sequenti-ally-treated fabric imparts dimensional stability onwash of an exceptionally high order.

3.2 Effects or Post-treatment using Different Types ofResin-A Comparative Study

DMDHEU and urea-formaldehyde (UF) resinsare commonly used in the textile finishing for

GHOSH et aL: JUTE-VISCOSE UPHOLSTERY FABRIC

achieving crease-resistant finish. In the presentstudy, two uncommon and newer resins, viz.acrylamide formaldehyde adduct (AMF, methylolacrylamide) and butylated urea formaldehyde(BUF, water insoluble) have also been applied onjute-viscose fabric and the observed effects havebeen compared with those observed using UFand DMDHEU (Tables 4 and 5).

3.2.1 Weight GainIn each case of resin post-treatment of the se-

quentially pretreated jute-viscose fabric, there issubstantial weight gain (4-7%) due to resin uptake(Table 4). A longer duration of pretreatment, par-ticularly for texturing, made the sequentially pre-treated fabric of a given size exhibit a lower resinuptake on resin post-treatment under comparable

283

conditions. This is understood partly on the basisof the fact that longer period of pretreatment,particularly for texturing, produced more compactfabric consequent to higher shrinkage (Table 3)which apparently led to lesser resin penetrationduring padding as practised here. Higher weightloss for a longer period of sequential pretreat-ments causes higher removal of resin-bindingsites, mainly the hemicellulosic constituents, in theamorphous zones of jute and this may also partlyexplain why resin uptake is lower in each case fora higher duration of pretreatment.

3.2.2 Tensile and Other PropertiesResin finish expectedly3.14.27.28makes the jute-

viscose fabric somewhat poorer in tenacity andbreaking extension (Table 4) much as a consequ-

Table 4-Effect of different resin post-treatments on weight gain and tensile propenies of sequentiallypretreated (textured and bleached) 60: 40 jute-viscose fabric

Resina Weight gain Fabric tenacity Breaking extension Modulus at 1% extension% N/mm % N/mm

x y X Y X Y X YNone 8.98 8.16 24.90 27.22 4.24 4.13DMDHEU 6.35 5.82 7.15 6.06 16.89 18.74 9.40 8.80UF 5.12 4.83 7.06 5.89 12.34 14.83 18.46 16.78BUF 7.02 6.52 8.09 7.15 30.42 32.87 10.50 9.8}AMF 5.37 5.10 7.87 6.85 15.59 18.57 16.75 13.95AMF 6.95 6.32 8.53 7.48 20.92 21.66 22.04 20.20

(presoaking with KZSZO~)b

X-Sequentially textured (18% NaOH) and bleached [50% HzOz (4% owf)j for 30 min each.Y-Sequentially textured (18% NaOH) and bleached [50% HzOz (4% owfj] for I h each.'Resin conc., 8%; Curing catalyst, MgClz; Curing temp., 150·C; and Curing time, 4 min.bPresoaking with K2SZ0~ was done to effect simultaneous vinyl polymerization and crosslinking.

Resina

Table 5 - Effect of different resin post-treatments on some physical properties ofsequentially pretreated 60 : 40 jute-viscose fabric

Moisture regain Dry crease recovery Abrasion resistance Bending length% angle (warp +weft) (No. of cycles to a em

deg specific wear)

X Y X Y X Y

None 16.50 16.08 134 138 46 53DMDHEU 10.32 11.7 235 240 37 42UF 9.48 10.6 212 216 27 31BUF 6.46 8.88 202 205 92 103AMF 25.48 27.47 225 228 38 45AMF 20.87 21.67 230 238 41 49(presoaking with K2S2OS)

X and Y-See Table 4.a and b-See Table 4.

X Y2.7 2.84.0 4.14.1 4.34.5 4.8

3.0 3.33.4 3.8

284 INDIAN J. FmRE TEXT. RES., DECEMBER 1994

ence of embrittlement caused by crosslinking to60% jute component in jute-viscose fabric and al-so for variable degree or unevenness of crosslink-ing of the cellulosic chain molecules through therigid resin moieties and, to a minor degree, due topossible chain degradation during the process, de-spise viscose part expectedly might cause someimprovement in tenacity. The opposing effects ofcrosslinking (a major effect) and of cellulose chaindegradation (a minor effect), however, result in asubstantial enhancement in the modulus value at alow (1%) extension, thereby increasing the fabricstiffness to a level such that the loss in stiffnessthe fabric suffered on the sequential pretreatmentis slightly or substantially or more than compen-sated on resin finish depending on the nature ofresin used (Tables 2 and 5). Changes in moistureregain, dry crease recovery (CR) angle, abrasionresistance and stiffness of the sequentially pre-treated jute-viscose fabric on different resin post-treatments are shown in Table 5. Each of the hy-drophobic cured resins, viz. DMDHEU, UF andBUF resin, expectedly leads to some drop inmoisture regain, while the hydrophilic resin AMFsignificantly improves the moisture regain. In eachcase of resin finish except BUF, there is a drop inabrasion resistance; the drop is less severe withAMF resin finish and more severe with UF resinfinish. The drop in abrasion resistance and gain instiffness of the fabric is apparently related to thepotential of the resin used to establish crosslinksand develop intrinsic rigidity, the order of whichis UF> DMDHEU > AMF.

BUF stands in sharp distinction in this context.Its prominent hydrophobic nature necessitates itsapplication in aqueous emulsion as described inthe experimental section. During application, itspenetration in the relatively hydrophilic fibrecomponents of the fabric was expectedly minimal.A high resin uptake observed is much a consequ-ence of surface deposition/adsorption of BUF onthe fabric and high resistance to removal by soap/water wash. BUF resin is also characterized by alow crosslinking potential and rigidity. However,location of the hydrophobic BUF resin in the sur-face layers renders the fabric show minimummoisture regain, relatively high breaking extensionand exceptionally high abrasion resistance. Poormoisture regain also renders the BUF-finished fa-bric exhibit high stiffness (Table 5).

3.2.3 Crease~overy AngleThe crease recovery angle of the sequentially

pretreated jute-viscose fabric improves substan-tially for all other resin treatments as for

DMDHEU treatment (Tables 2 and 5). Cure ofthe methylolated resins applied on the fabric at150°C for 4 min in presence of MgCl2 as the cur-ing (acid) catalyst imparts improvement in creaserecovery angle in the order DMDHEU = AMF>UF> BUF. The results of application of AMFand DMDHEU with respect to improvement increase recovery angle become comparable whenfor the AMF system, a free radical catalystK2S20S (nearly 0.5% owf), allowing chain polym-erization of the vinyl moieties of AMF resin, isused along with MgCl2 which at the high curetemperature functions as the usual (acidic) curingagent.

4 Conclusions

4.1 Sequential texturing and bleaching pretreat-ment imparts certain desirable property benefitsor advantages over only texturing Of bleaching,particularly . with respect to high extensibilitydeveloped, and good improvement in crease re-covery angle after resin finish despite some margi-nal drop in fabric tenacity.

4.2 The drop in tenacity on sequential pretreat-ments suffers further drop, to different extents, onresin finishing depending on the resin type used;for UF, DMDHEU and BUF resins, further dropin tenacity is 21-27%, 20-25% and 10-12% re-spectively while for AMF resin, the drop is5-15%. The increase in initial modulus on resintreatment is 300-330%, 110-120%, 140-150%and 250-400% for UF, DMDHEU, BUF andAMF respectively.

4.3 While all other resin finishes lead to a lower-ing of moisture regain in view of Hydrophobic na-ture of those resins, AMF resin finish does theopposite in view of its prominent hydrophilic na-ture. The increase in moisture regain of the pre-treated fabric on AMF resin finish is as high as25-70%.4.4 Considering resin uptake, crease recovery,abrasion resistance, tenacity, modulus, extensibil-ity and moisture regain, AMF resin finish allow-ing simultaneous radical polymerization (inducedby K2S20S) of the vinyl units and acidic crosslink-ing (induced by MgCI2) utilizing the methylolgroups produce the best balanced effects on jute-viscose fabric. Thus, controlled sequential textur-ing and bleaching (30 min each) followed byAMF resin finish (as in the last expt. in Table 5)make jute-viscose (60: 40) fabrics more prospec-tive for upholstery and related applications.

GHOSH et al: JUrE-VISCOSE UPHOLSTERY FABRIC 285

AcknowledgementOne of the authors (AKS) is thankful to Dr N

C Som, Head, Chemical Processing Division, In-RA, Calcutta, for supplying the jute-viscose fabric.He. is also thankful to Dr U Mukhopadhyay,Principal, Institute of Jute Technology, Calcutta,for providing all facilities and necessary help forthe work.

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