Indian Journal of Textile ResearchVol. 12, June 1987, pp. 78-87

Wrinkle Resistance and Tensile Strength of Jute-based FabricsModified by Treatment with N-Methylol System: Part I-Effect of

Treatment in Presence of Inorganic Salt Catalysts

N C SOM, A BAGCHI and A K MUKHERJEEApplied Chemistry Division, Indian Jute Industries' Research Association, Calcutta 700 088, India

Received 31 October 1986; accepted 2 February 1987

The potentiality of the jute fabric to develop wrinkle resistance,with a view to using it in diversified applications, hasbeen examined. Jute fabrics develop wrinkle resistance to a satisfactory level through cross linking with common reagentslike urea formaldehyde, melamine formaldehyde, dimethylol ethylene urea and dimethylol dihydroxyethylene urea in thepresence of catalysts. The changes in properties of jute fabric, particularly the wrinkle resistance and tensile strength at var-ious conditions of concentration of resin-catalyst systems, duration and temperature of curing, etc., were examined. Theresults, when compared with those of cotton fabrics, indicate that there are some common trends of relationship betweenwrinkle resistance and tensile strength of jute fabric, but with some deviations in the latter. The results of crosslinking ex-periments with the above-mentioned resins, using inorganic salts as catalysts, are discussed. .

Keywords: Jute-based fabrics, Dimethylol dihydroxyethylene urea, Dimethylol ethylene urea, N-methylol urea, Tensilestrength, Wrinkle resistance

1 IntroductionThe diversified use of jute in the fields other than

wrapping and packaging has become a matter of greatimportance in the jute industry. New outlets being ex-plored for jute in wider textile fields, such as furnish-ing upholstery and apparel, call for substantial im-provements in certain properties of the jute fabricthrough better wet-processing such as bleaching, dye-ing and finishing. A new bleaching process has beendeveloped to impart a higher light fastness 1• This hasopened up newer areas for utilization of jute fabricsfor sophisticated uses. As compared with cotton, jutehas several deficiencies in properties and thereforejute fabrics must be endowed with certain essentialfunctional requirements such as soft handle anddrape, good dimensional properties, recovery fromwrinkles and so on.

Jute differs from cotton in chemical composition.While the cotton fibre is purely cellulosic, jute con-tains cellulose (62-64%), hemicellulose (21-23%)and lignin (13-14%) as major constituents. Owing tothe presence of good amounts of non-cellulosic con-stituents, the actions of chemical reagents are some-what different on jute as compared with their actionon cotton, and are likely to influence the fibre pro-perties. Very little work has been reported in the liter-ature on the effect of crosslinking agents on the physi-cal and chemical properties of. jute fabric such aswrinkle recovery, strength, feel, etc. Das and Ghosh?

78

made some preliminary investigations on the effect offormaldehyde crosslinking on the strength andwrinkle recovery properties of jute fabric. Theseworkers observed high wet wrinkle recovery but poordry wrinkle recovery on prolonged treatment of jutewith formaldehyde in the presence of magnesiumchloride, citric acid and a combination of the two ascatalysts, at room temperature.

It was further reportedv' that formaldehyde treat-ment on alkali (NaOH)-swollen jute fabric by a pad-dry-cure method shows improved dry wrinkle re-covery. Sengupta and Radhakrishnan' mentioned intheir review that a high degree of wet wrinkle recovery(280- 3000)and low to moderate dry wrinkle recovery(220-250°) properties can also be achieved by usingcrosslinking agents like dimethylol ethylene urea(DMEU), dimethylol dihydroxyethylene urea(DMDHEU), etc. on 5% NaOH-pretreated jute fa-bric. However, these treatments were accompaniedwith 50-70% loss in tensile strength, and the studieswere of a preliminary nature.

It was therefore felt worth undertaking a detailedstudy on the effect of different types of well-knowncrosslinking agents such as urea formaldehyde (UP),melamine formaldehyde (MF), DMEU andDMDHEU on jute fabrics with a view to improvingtheir physical and chemical properties, especially thewrinkle-resistant properties, as jute is highly suscepti-ble to creasing during use and on wetting. In this pa-

--

SOM et al.: WRINKLE RESISTANCE AND TENSILE STRENGTH OF JUTE - BASED FABRICS

per, we report the results of studies on the effect oftreatment of jute with some N-methylol urea cross-linking agents in the presence of inorganic salt .catal-ysts on wrinkle resistance and strength retention ofthe jute fabric.

2 Materials and Methods2.1 Materials

2.1.1 FabricPlain weave 100% jute fabric was used throughout

the work. It had the following structural characteris-tics: Warp-60 ends/dcm (count, 340 tex); Weft-48picks/dcm(count, 270 tex); and Fabric mass per unitarea (at 67% RH and 20°C)-325 g/m-,

The fabric was cleaned before use by scouring with2% sodium carbonate (on fabric weight) at 80°C for30 min. Bleaching was carried out in a laboratory jig-ger by means of alkaline hydrogen peroxide. This wasfollowed by washing with water, treatment with aceticacid and finally with water to give a fabric pH of 6.0-6.5.2.1.2 Chemicals

The following chemicals were used:(1) Ahuramine SRUF, an aqueous product con-

taining 43% solid urea formaldehyde (1.0:1.6); Ahu-ramine KETU, an aqueous product containing 46%solid dimethylol ethylene urea; Ahuramine MF, anaqueous product containing 46% solid melamine for-maldehyde; and Ahuramine YX, an aqueous productcontaining 51% solid 1,3-dimethylol-4,5-dihydroxy-ethylene urea.

(2) Diammonium hydrogen phosphate, magne-sium chloride hexahydrate, zinc chloride. zinc nitrate,ferric chloride and aluminium chloride, all of analyti-cal grade, were used as catalysts.

2.2 Methods2.2.1 Measurement of Wrinkle Recovery

Dry wrinkle recovery was measured by the Mon-santo crease recovery tester in accordance withASTM D 1295-67; and wet wrinkle recovery wasmeasured in the same way as dry wrinkle recovery ex-cept that prior wetting of the specimens was madewith an aqueous solution of surface-active agents, andexcess water was soaked with filter paper.

2.2.2 Measurement of Tensile StrengthTensile strength was measured by the ravelled strip

(20cm X 5cm)methodonanlnstronmachine(mod-el TTBM). The percentages of nitrogen in theuntreat-ed and crosslinked jute fabrics were determined bythe Kjeldahl method.

2.2.3 Application of Crosslinking (Reaction) AgentsThe fabric samples, each of 40 cm x 125 em, were

impregnated with aqueous solutions of the crosslink-

ing agent and catalyst on a 3-bowllaboratory paddingmangle (Ernst Benz & Co. model KI..:FH-K-~W), us-ing 100% wet pick-up. Unless otherwise specified, thefabric samples after padding were dried at 80°C for 5min and cured at 150°C for 5 min in a laboratory cUJ-ing unit (Ernst Benz & Co. model KTFIM), followedby washing with soap solution (5 g/Iitre )ina laborato-ry jigger, rinsed with water an? finally dried. .

The catalysts were used at different concentrationsfrom the lowest to a little higher than the level recom-mended generally in cotton-cellulose crosslink-ing6,7,8. Seven different types of catalyst were used.The resins studied most extensively with cotton cellu-lose were used. The resins were applied at a little high-er concentration than that generally found to give opt-imum wrinkle recovery for cotton fabrics. The appli-cation conditions were identical in all cases: 12% solidresin solution in the pad bath (and making 12% resinadd-on on the weight of the fabric )and 0.1%non-ion-ic wetting agent (on the volume of the bath). Lowerand higher resin add-ons on the jute fabric were alsoevaluated on a selected experiment, as specified in theresults and discussion. The cured fabrics were condi-tioned at 67% RH and 25°C.

The processing variables and conditions used inthe studies in respect of various resins and catalystle-vels of treatment are given in Table 1.The conditionschosen were prescribed in part by practical ranges inthe textile literature and in part by the acceptable re-quirements of physical properties of the treated cloth.The experimental designs were accordingly made sothat a wide range of resin catalyst systems could beevaluated to ascertain the potentiality of resin-finish-ing on jute fabrics6,7,9.

3 Results and Discussion3.1 Wrinkle Recovery

The effects of different catalyst concentrations onthe wrinkle recovery, imparted by various resin-ca-talyst systems, are shown in Figs la - f. In these sets ofexperiments, resin add-on was 12% on the weight ofthe fabric and the curing was done at t50°C for 5 min.The amount of wrinkle recovery imparted to a cellu-losic fabric by a crosslinking agent is known to be re-lated to the type and concentration of the resin and ca-

. f . t 6710talyst, duration and temperature 0 cunng, e c. " .The results show wide variations in wrinkle recoveryangles with different resin-catalyst systems. The drywrinkle recovery (W + F) varies from 100 to 260 de-grees.

Of the resins used in different resin-catalyst reac-tions for their action on the jute fabric, UF and MFshowed inferior wrinkle recovery to DMEU andDMDHEU. DMDHEU gave the highest wrinkle re-covery angle. Ammonium salt catalysts (diamrnoni-urn phosphate and anunonium chloride) were effec-

79

INDIAN J. TEXT. RES., VOL. 12, JUNE 1987

Table l=-Processing Variables and Conditions Used in the Reaction of Different Resinswith Jute Fabric in Presence of Various Catalysts

4,6,8,16

0.6(5.0),0.9(7.5),1.5(12.5),2.1(17.5),2.4(20.0)0.36(3.0),0.72(6.0), 1.08(9.0), 1.44( 12.0)0.50(4.17),1.0(8.34),1.5(12.51),2.0(16.6),2.5(20.8)3.0(25.02),3.5(29.2),4.0(33.35),4.5(37.53),5.0(41.7)0.6(5.0),1.2(10.0),1.8(15.0),2.4(20.0), 3.0(25.0), 3.6(30.0)0.5(4.17),1.5(12.51),2.5(20.8),3.5(29.2),4.5(37.53)0.25(2.08),0.5(4.17), 1.0(8.34), 1.5(12.51)

UF,MF 150°C

Processing variables

UFandMF%

DMEU andDMDHEU%

DMDHEU%

Catalyst cone.", %(Catalyst ratio %based on resin)

Limits of variables Catalysts

DAP, NH4Cl, ZnCI2,

MgCI2·6HzO

DAP, NH4Cl, ZnCIz,MgCI2·6H20, Zn(N03lz,AlCI3, FeCl3MgCI2,6H20

DAPNH4ClMgCI2·6HzO

12

12

ZnCI2 and Zn(N03)2

FeCl3AlCl3

DAP, NH4Cl, MgCI2•

6HzO,ZnCI2

AllMgCI2·6H20

Curing temp., °C DMEU, DMDHEU 150°CDMDHEU 110°C, 130°C, 150°C, 170°C

DMEU, DMDHEUDMDHEU

Pick up (%) UF, MF, DMEU,after padding OMDHEU

aActual catalyst cone. in pad bath. Catalyst ratio % based on resin equals the catalyst cone./resin conc., e.g. for a solution containing 2%catalyst and cone. of resin of 12%, the catalyst ratio is 16.34% or 2112 x 100 = 16.34.

UF,MF

Curing time, min

5 OAP, NH4Cl, MgCI2.-

6HzO,ZnCI2

53,5,7,10,15

100

tive in the case of UF and MF resins, whereas metalsalts like MgCl2 and ZnCl2 were effective for DMEUand DMDHEU; AlCl3 gave reasonable wrinkle re-covery angles with DMEU andDMDHEU, but FeCl3gave the poorest wrinkle recovery angle with theseresins. UP gave a reasonably good wrinkle recoveryin the presence of diammonium phosphate catalyst inthe range 0.6 -1.5% concentration (242°), which thendecreased with higher concentrations. This may bedue to the acid hydrolysis of fibres, resulting in em-brittlement. Other catalysts used with UF as the resingave poor to moderate wrinkle recovery (190-23()'0).A similar trend was obtained with MF resin whichgave the highest wrinkle recovery angle with diammo-nium phosphate catalyst. The possible explanationsof the poor wrinkle recovery angle of jute fabric treat-ed with UP and MF resins are:

(1) The amount of resin polymerized within thenon-cellulosic constituent of jute fibre is higher thanthat within the cellulosic portion.

(2) As jute is a stiff fabric, treatment causes furtherstiffening of the fibre surface owing to the depositionof the resin polymer on the fibre surface, resulting in apoor wrinkle recovery angle.

80

(3) The size of the monomeric unit, shape andlength of the crosslink between the chains of cellulose(and hemicellulose and lignin) also affect the propert-ies of the crosslinked fabric.

The wrinkle recovery obtained with DMEU in thepresence of different catalyst systems varies with theconcentration and type of the catalyst. Of theinorgan-ic salts, FeCl3 gives the poorest wrinkle recoveryangle (range 182-204°), MgCl2 and Zn(N03lz givegood wrinkle recovery (182-254° and 178-284° re-spectively), while diammonium phosphate and zincchloride show intermediate wrinkle recovery angles(220-244° and 196-238° respectively).

Of the different resin-catalyst systems investigated,the DMDHEU-MgCI2 system provides the highestwrinkle recovery angle (190- 260°), the poorest beingobtained in theDMDHEU-FeCI3 combination (218-224°). Other catalysts [DAP, ZnCi2, Zn(N03)2 andAlCI3] give intermediate wrinkle recovery angles(194-248°). The resin concentration, temperatureand duration of curing remain constant in all the resin-catalyst systems with the jute fabric; the wrinkle recovery angle increases with increase in the concentra-tion of the catalyst in pad bath (except the UP andMF/DAP systems where maximum wrinkle recover-

260

250

240

230

220

210

200

SOM et al.: WRINKLE RESISTANCE AND TENSILE STRENGTH OF JUTE - BASED FABRICS

(a)

• - UFX -MF~ -OMEUo -OMOHEU

190

0'5 1'0 1'5 2'0 2'5 3'0

(d)

o - UFX - MFo -OMEU

e - OMOHEU

( b)

• - UF

x -MF• -DMOHEUO· -DMEU

o 0 '2!1 O'!I 0"7!1 1'0 1"25 re(e)

• - OMEU/ AI CI3o - OMOHEU/AICI3

o - OMEU/FeCI3

e - OMOHEU/ FeCI3

(c)

2300'

~ 220

W~ 210Z< 200>5 190>o 180+---.---r--r---.--'r---,~ 00: 260W-'~ 250Z0: 240~

• -UFX - MF

o - DMEU~ - DMDHEU

1'0 2'0 30 4'0 5'0 6'0

(f)

• - DMEU

x -DMDHEU

0'5 1'0 1'5 2'0 2'5 3'0 3'5 0 0·5 1'0 1'5 2'0 2'5 3'0 3'5 4'0 4'5 0.5 1'0 1"5 2'0 2'5 3'0

CATALYST CONe. ,OfoFig. I-Effect of catalyst concentration on wrinkle recovery imparted by various resin-catalyst systems ICatalysts-tal Diammoniumphosphate, (b) Ammonium chloride, (c) Magnesium chloride, (d) Zinc chloride, (e) Aluminium chloride, and Ferric chloride, (f) Zinc

nitrate]

ies were obtained at the initial concentration, up to acertain limit; further increase in concentration causesa fall in wrinkle recovery). The optimum concentra-tion of catalyst for optimum wrinkle recovery is de-pendent upon the resin and varies from catalyst to ca-talyst. The maximum wrinkle recovery obtained withdifferent resins and catalyst combinations at 12% res-in add-on is shown in Fig. 2. This shows that there arewide variations in wrinkle recovery amongst metallicsalts in the case of all the four resins. The trends of theeffectiveness as just described above are summarizedas follows:

In general, metallic salts are more effective thanammonium salt catalysts; MgCI2.6H20 gives the bestresults. Fig. 2. focuses attention on the wrinkle re-covery only, neglecting other properties such as ten-sile strength, etc., which will be discussed later. Thedifferences in wrinkle recovery angle at a given resinconcentration and increasing catalyst concentrationmay be due to the difference in the action of theseacidic salts at a high curing temperature, causingbreakdown of the carbohydrate chains.

As a DMDHEU-MgCI2 combination gives moreconsistently improved wrinkle recovery properties

mil NH4CI

~MgCI2

es Zn CI2I!i'i'l Zn (No3)2

-FeCI! IT

IlilllAI CI3V

'II, I I,'I I' 'II I

I' !I , I'II I ,I

~ II I' I I,ii ,I I 'I\ Ii I I·\ I: ·1 II 'I\ II I, ~:I,\ II 'I 'I\ II ~!iII

,II I,

\ . II 1 II 'I,\ II II I!i

rnIIlIDAP280

270

"'260""0.

j 250

"z•• 240,.::; 230>o~ 220a:

j 210'"z~ 200•

190

180 UF MF OMEU12'lb RESIN-60LIOS

OMDHEU

Fig. 2-Maximum wrinkle recovery obtained with different resin-catalyst systems

on the jute fabric at different concentrations ofMgCl2than any other resin-catalyst system studied, the ef-fects of concentration ofDMDHEU at a given dura-tion and temperature of curing and concentration of

81

INDIAN J. TEXT. RES., VOL. 12, JUNE 1987

catalyst were investigated to arrive at an optimumadd-on of DMDHEU required for jute fabrics forpractical purposes. Fig. 3 shows the trend of wrinklerecovery of jute fabric at different DMDHEU add-ons with and without MgClz. The crosslinking reac-tion did not take place in samples without the catalystup to a resin add-on of 4% where the wrinkle recoveryof untreated jute fabric rose from 165 to 170° only andbound nitrogen from 0.13 to 0.17%. In fact thenitrog-

270

260en'""0_ 250

'".J'" 240z"">- 230a::

'"> 2200:>

'"a:: 2.0.....J

zoo"zIE~ .90

'80 • - DMDHE~/MgC'Z(3%)

'70o - DMDHEU ONLY

I I • I4 8 .2 '6 20

0,. OMDHEU - Solida

Fig. 3-Effect of DMD HEU resin add-on with or without catalyston wrinkle recovery of jute fabric

en content of raw jute fibre varies from 0.1 to 0.18%.So an incremental value of 0.04% nitrogen content in4% DMDHEU treatment does not indicate signifi-cantly the crosslinking reaction. At 8, 12, 16 and 20%DMDHEU treatments in the absence of any catalyst,there is a marginal improvement in wrinkle recovery,which slowly increases as the concentration ofDMDHEU increases. The pH of jute fabric is around6 owing to the acidic nature of jute fibre and the acidiccharacter possibly gives some catalytic effect whilecuring, which contributes to the crosslinking reactionof the jute fabric and DMDHEU. The nitrogen con-tent of the treated fabric (Table 2) supports the viewthat some reaction has taken place at 8-20% con-centrations of DMDHEU. In the presence of MgClzcatalyst, the wrinkle recovery of jute fabric increaseswith increase in DMDHEU concentration in pad-bath and levels off at 12% add-on. Though furthercrosslinking occurs at 16% level as indicated by ni-trogen content (Table 3), wrinkle recovery is arrestedowing to the loss of elongation of fibre. The extent ofimprovement of wrinkle recovery (from control 165°to treated 260°) of jute fabric due to crosslinkingtreatment is however not significant when comparedwith that of cotton fabric, which gives a much higherwrinkle recovery angle (from control 170° to treated

Table 2-Add-on, Nitrogen Content, Wrinkle Recovery and Tensile Strengthof Fabric Treated with DMDHEU in Absence of Catalyst

% Nitrogen in % Nitrogen in Dry wrinkle Wet wrinkle Tensile strengthfabric before . fabric after recovery recovery

curing curing and (W + F) (W + F)washing

0.130.170.410.560.680.72

% Add-on ofDMDHEU(solid)

Nil48

121620

0.130.811.642.733.424.15

165170188202210210

165168170172170172

Warpkg

84.0082.3281.4880.4080.5078.12

Weftkg

54.053.053.252.752.552.7

Table 3-Add-on, Nitrogen Content, Wrinkle Recovery and Tensile Strength of Fabric Treatedwith DMDHEU in Presence of Catalyst (MgCl2)

% Add-on of % Nitrogen in %Nitrogen in Dry wrinkle Wet wrinkle Tensile strengthDMDHEU fabric before fabric after recovery recovery(solid) curing curing and (W+ F) (W+ F) Warp Weft

washing kg" kgNil 0.13 0.13 165 165 84.0 54.04 0.81 0.75 190 198 71.4 46.06 200 198 63.25 41.08 1.64 1.37 234 228 58.5 37.2

10 255 246 55.8 37.012 2.73 1.75 260 255 56.7 38.014 260 256 43.7 36.416 3.42 2.40 260 258 38.6 35.118 232 138 31.9 24.420 220 236 26.9 20.1.

82

SOM et al: WRINKLE RESISTANCE AND TENSILE STRENGTH OF JUTE - BASED FABRICS

2800-2900)with a lower resin add-on (7-8%) at similarprocessing conditions. It appears that the jute fabricas such has limitations in crease recover; characteris-tics owing to the nature of the fibre., i.e. stiff andcoarse, brittle and poor elongation property, andtherefore some kind of pretreatment is required toovercome these drawbacks.

The effect of the duration and temperature of cur-ing on wrinkle recovery properties of jute fabric by us-ing optimum concentrations of DMDHEU andMgCl2 catalyst are shown in Fig. 4. The results indic-ate that the wrinkle recovery of jute fabric increaseswith the duration and temperature of curing. Thehighest wrinkle recovery was obtained at 170°C (atany reaction time) and then decreased on increasingthe temperature of curing. There is a direct relation-ship between the duration and temperature of curing.In the range nO-130oe, wrinkle recovery increaseswith duration of curing. At IS0°C, wrinkle recoveryreaches the optimum stage in 5 min duration of curingfollowed by downward wrinkle recovery values in 7min, 10 min and 15 min duration of curing. The cross-

linking reaction at a higher temperature (170°C)shows a typical downward trend of wrinkle recoveryvalues with increasing duration of curing startingfrom 5 min. In 3 min duration of curing, wrinkle re-

26°1!250

';240...J

'"~ 230

~ 220'">8 210'"0:

200'"...J~ 190ii~ 180

DURATION OF CURING• -.3 min.

X - 5 "o - 7 tt

• -10 II

11 -I~ .,

170+---+---,------.---__._---,110 130 150 170

CURING TEMP.,"c

Fig. 4-Effect of duration and temperature of curing on wrinklerecovery of jute fabric in DMDHEU (12% o.w.f.I-MgCl,

(3%o.w.f.)system

10 (0) (b) (e)90

80

70~ .

~

60

~50;l.40z

o 30~~ 20~W 10a::I O+--.-.--,-.--.-r-__._-r--r+--,----.'----.I--~I--~_.--_.--__._--__._--,_-__,0 0·6 0·96 1'45 2·0 2'~ 036% 0'72 1'08% 1·44

Z 100W~ 90If)

• - UF

X - MF·• - OMEU° - OMOHEU

• - UFX -MF.

• -OMEUo -ONOHEU

• - UF

X - MF• - OMEU" - ONOHEU

Cd)

1% 2% 4% 5% 6

(el

e -OMEUo - OMOHEU

(I)

o -ONEU/FeC'3Q -ONOHEU/FeCI.3X - ONEU/AIClj• - ONOHEU/AICI3

oe I'SI Iis 2'S 3'S

CATALYST CO NC.,o,oo· O'S

Fig. 5-Effect of catalyst concentration on tensile strength retention of jute fabric in various resin-catalyst systems [Catalysts-( a) Diam-monium phosphate, (b )Ammonium chloride, (c) Magnesium chloride, (d) Zinc chloride, (e) Aluminium chloride, (f)Zinc nitrate 1

80W...J

70If)Z 60W~

50

40

30

20e -UFX - NF

10 • - ONEUe - ONOHEU

0

83

INDIAN J. TEXT. RES., VOL. 12, JUNE 1987

covery increases with temperature of curing up to170°C. It is not desirable to cure at still higher temper-atures because of the possibility of pyrolysis of jute.

3.2 Tensile StrengthThe effects of resin finishing on tensile strength of

jute fabrics are shown in Figs 5a-f. Here, the tempera-ture and duration of curing were constant at 150°Cand 5 min. As can be seen, DMEU and DMDHEU-treated fabrics retain a slightly higher tensile strengththan UF-treated fabrics, with different catalysts. Thestrength losses caused by crosslinking reactions de-pended upon the concentration ofthe catalystS,II-13.

As the concentration of the catalyst increases, inde-pendent of the resin, the retained tensile strength dec-reases. At higher concentrations of the catalyst, re-tained tensile strengths (52-64%) arelower in the caseof UF/diammonium hydrogen phosphate and MFIdiammonium hydrogen phosphate combinationsthan the DMEU and DMDHEU/diammonium hy-drogen phosphate system (70%). NH4Cl retains moreor less the same tensile strength (55-62%) with all thefour resins. When MgC12 was used as catalyst, reten-tion of tensile strength of the fabric was dependentupon the resin type, e.g. with DMEU, the fabric re-tained the lowest tensile strength (40%); with UF andMF, it retained intermediate tensile strength (55%),whereas with DMDHEU the fabric retained the high-est tensile strength (60%). At an identical concentra-tion of catalysts in the resin pad bath, AICl3 gives low-er tensile strength retention values (at 1.5% cone., 55-60%) than the other catalysts. Fig. 5f shows that therate of decrease in retained tensile strength is higher inthe case of AICl3 than in the case of the other catalysts,namely FeCI3, ZnCl2 and Zn(N03}z.

It is interesting to note that the catalyst alone causeshigher losses in tensile strength than resin-catalystsys,tem. This indicates that the loss in strength by de-

_ 100~zOOo

~ 80...•..~ro

~ 60ez~ 50•..VI o - BLANK FABRIC

(5. mH'" CURE TIME)• - 3 .rnin. CURE TIME

X -s "o -.7 "• -10 u t.6 -IS ••

40...-'u; 30z...•..20

10+----,,----rl----,'-----.I----,110 130 150 170

CURING TEMP. ,oe

Fig. 6-Effect of duration and temperature of curing on tensilestrength retention of jute fabric in DMDHEU (12% b.w.f.)-MgCI2

(3%0.w.f.)system

84

gradative action of catalysts is prevented by cross-linking!". Water treatment has no effect on tensile pro-perties of jute fabric cured at different temperaturesfor 5 min (Fig. 6, blank fabric ).Strength loss due to thecatalyst alone is less at lower concentrations and ismuch more at higher concentrations (Fig. 7).

The effects of duration and temperature of curingat a given concentration ofDMDHEU and MgC12 onstrength retention of jute fabric are shown in Fig. 6.The effect is not pronounced at lower temperatureswith respect to duration of curing but as the tempera-ture increases, retention of strength varies widely withprogressive increase in duration. The retainedstrength of the crosslinked fabric treated with theDMDHEU-MgC12 system at 150°C for 3-5 min curetime is around 68-70%, whereas it is around 53% forcuring durations between 7 and 15 min at 150°C, i.e.there is a sudden fall in retained strength on increasingthe duration of curing from 5min to 7 min and on-wards.

Fig. 8 shows the effect of treatment of jute fabricwith varying concentrations of DMDHEU (in pad-

100

10

• - NH4C1o -DAP

II - MOCI2C - Zn-'CJ2

11 - Zn ( NO~)2• - F, CI3x - AICI!

0+-,--.-,--,-,--,-, __,-,--,o 0'5 1'0 1'5 2'0 2'5 3'0 3'5 4'0 4'5 5'0

CATALYST CONC.,%

Fig. 7-Effect of inorganic salt catalyst concentration on tensilestrength retention of jute fabric, in the absence of any resin, cured

at 150°C for 5 min

100~90

i 80zo;:::70z'"~ 60

~ SOz~ 40•....,",30...J

~ 20w•...

10• - OMDHEU I MQCIZ (3 %;o - DMDHEU ONLY

4 8 IZ 16 200/. DMDHEU - Solid,

Fig. 8-Effect of DMDHEU resin add-on on tensile strengthretention of jute fabric

SOM et al: WRINKLE RESISTANCE AND TENSILE STRENGTH OF JUTE - BASED FABRICS

bath) with or without MgC12 at 150°C curing tempera-ture for 5 min duration. There is very little loss in thetensile strength of jute fabric when treated withDMDHEU without any catalyst. It is expected thatowing to the increase in wrinkle recovery of jute fa-bric, though marginal due to the above treatment, itshould suffer loss in tensile strength. As mentionedearlier, the metal salt catalyst used in the studies alonecaused degradative action on jute fabric at the curingtemperature. The absence of any catalyst in the reac-tionsystemhas not contributed to any reasonable lossin strength, though there is a marginal improvement inwrinkle recovery. Some of the resin-catalyst reactionsystems with the jute fabric also show that the loss instrength is very little or marginal when the wrinkle re-covery is in the range 170°-205°. The strength of thefabric deteriorates with increasing concentrations ofDMDHEU in the presence of MgC12 and at 8-12%resin add-on level, retention of strength is in the ac-ceptable region and at higher add-on, the loss instrength is considerable.

It iswell established that the application of resin fin-ishing to the cotton cellulose fabric is accompaniedwith reductions in tensile strength and other physicalproperties. The jute fabric is also likely to behave in asimilar manner. These losses have been attributed tofactors induced by crosslinking of cellulose mole-cules. Because chain lengths of jute cellulose are

100UF - RESIN

90 (o )

eo 60

70 0

;! 60 6

Z' 0

Q 50l- • - DAP

Z 40 o - NH4C.WI- 30 A - ZN e'2

W a - MIQC'20:

20II- 10 , I I , , I I , I<::J '70 .so 190 200210 220 230 240 250 260 270ZW 100 DMEU - RESIN (d)0:I-If) 90

W 6~ 80 6If)Z 70WI-

060 --.--- a50

0 a40 • - NH4C1

6 -DAP

30 o -Mg Clzo - F. Cia

20

10170 180 190 200 210 220 230 240 250 260

Mf- RESIN

o

• - DAP

o - NH4CI

a - ZnC'2

a - MQ e'2

smaller than those of cotton cellulose the effect is pro-nounced. The presence of hemicellulose and lignincontaining a reduced number of hydroxyl groups,which may be crosslinked through the resin, may con-tribute to further losses in physical properties.

3.3 Tensile Strength vs Wrinkle RecoveryIt has been established in the case of cotton cellu-

Iose." that there is a relationship between tensilestrength and wrinkle recovery. As the wrinkle re-covery increases, the tensile strength decreases. Figs9a-f show the relationship between the wrinkle re-covery angle and per cent tensile strength retention ofthe jute fabric treated with different resin-catalyst sys-tems. At equivalent wrinkle recovery value, MgCl2

shows the lowest retention of strength in both UF andMF (Figs 9a and 9b). A significant negative correla-tion (correlation coefficient r = 0.67) is obtained be-tween wrinkle recovery and tensile strength retentionin the case of UF resin with all the catalysts used, ex-cept the DAP catalyst (Fig. 9a). The wrinkle recoveryangle is, however, found to be invariant with decreasein tensile strength retention as the concentration inDAP catalyst is varied. A similar trend is observed inthe case of MF resin treatment (Fig. 9b); the correla-tion coefficient in the latter case (r = 0.48) is howeversmaller than that in the former.

Contrary to the general observation of a linear rela-

( b)DMDHEU - RESIN

o oo

(c)

006o o

o

o -NH4 CI

6 -DAP

o-MgC12

o - Ft C:3

170 rao 190 200 210 220.230 240 250 260

DMDHEU- RESIN

0_ Zn(N,,*

0- Zn CI2

6- AI Cl3

180 190 200 210 220 230 240 250 260 270

(e) OMEU - "S,N ( f )o

o

66

6~ 0

oo

oo

o

e-Zn(N03

)2

O-ZnCI26-AICIJ

180 190 200 210 220 230 240 250 260 270 180 190 200 210 220 230 240 250 260 270

WRINKLE RECOVERY ANGLE ,deg

Figs. 9(a-f)- Relationship between wrinkle recovery angle and tensile strength retention of jute fabric in various resin-catalyst systems

85

INDIAN J. TEXT. RES., VOL. 12, JUNE 1987

tionship between wrinkle recovery and per cent ten-sile strength retention, it was found that a plot ofwrinkle recovery angle against the tensile strengthretention on treatment of jute fabric with DMEU andDMDHEU in the presence of catalysts like NH4Cl,DAP, (NH4}zHP04, MgC12.6HzO and FeC13 shows anon-linear and parabolic type curve (Figs 9c and 9d)respectively. The figures show that the wrinkle re-covery increases with the lowering tensile strength ofthe fabric and the phenomenon is valid up to a levelwhere maximum wrinkle recovery is reached andthen at the same wrinkle recovery, the tensile strengthretention continues to decrease and finally takes a re-verse path, i.e. at this stage the wrinkle recovery angledecreases with decrease in tensile strength. The rateof fall of tensile strength retention is different for dif-ferent catalysts in both DMEU and DMDHEU fin-ishes but the nature of change of these two propertiesis dependent upon the catalyst type.

The decrease in wrinkle recovery and tensilestrength retention of cotton fabric was also observedby Peterson" and Reeves et al.14 at high concentr-ations of the catalysts, apparently due to the hydroly-sis of th,; crosslinks and acid hydrolysis of the cellu-lose respectively. In fact the point of inflection on thecurve in the Figs 9c and 9d indicates the optimumcondition of finishes and may be considered for fin-ishing.

The jute fabric exhibits the maximum wrinkle re-covery along with the optimum strength loss up to a le-vel of crosslinking reaction in any resin-catalyst sys-tem used in this study. Further acceleration of thisreaction by increasing either the resin and/or catalystadd-on or increase in duration and/or temperature ofcuring resulted in the loss of elongation of jute fibreowing to the formation of covalent bonds. The loss inelongation of the jute fibre (jute has very poor elonga-tion property, 1.5% at break) causes embrittlementwhich cracks the fibres in the fabric at the time ofwrinkle recovery measurement and ultimately the fi-bres cannot recover from creases though a sufficientcrosslinking has taken place as evident from nitrogencontent (Table 3, Fig. 10). For this reason, the tensilestrength retention of fabric continues to decrease ow-ing to crosslinking with decrease in wrinkle recovery.

A good correlation exists between the wrinkle re-covery angle and per cent retention in tensile strengthboth in the case of DMDHEU and DMEU resintreatments in the presence of catalysts like Zn(N03lz.znC12 and AlC13 (Figs 9c and 9f); the higher thewrinkle recovery angle the lower the per cent reten-tion in tensile strength as in the case of UF and MFresins (Figs 9a and 9b).

The correlation coefficient is - 0.77 in the case ofDMDHEU and - 0.93 in the case of DMEU. The re-lationships between the tensile strength retention (%)

86

270l( 0) 100

§ ::1 9()

'10

~ 2400

70>-~ 230 600~ 220IX

'" 210 - • eo..J

'"~ 200 30,.190 20

180 10

170 f-a 12 16 20

". OMOHEU - Solid.

100

1( b)

90·

lso •~ 70 •~'"t:i 60IX

~ 00z'" 40'"..•• 30

'"..J~ 20

'"•. 10

170 180 190 200 210 220 230 t40 2!50 260 270WR!HKLE RECOVERY ANGLE, d~9

Figs 1O( a & b)-Relationship between wrinkle recovery angle andtensile strength retention of jute fabric at varying add-ons of

DMDHEU resin in the presence of catalyst (MgCI2)

and the wrinkle recovery angle for the two treatmentsare as follows:

% Tensile strength retention ~~192.95 - 0.57 wrinklerecovery for DMDHEU (r = - 0.77)% Tensile strength retention = 191.69 - 0.57 wrinklerecovery for DMEU (r = - 0.93)

Different tensile strength values are obtained,mostly at higher wrinkle recovery, and further in-crease in any processing variable shows reduction intensile strength retention with the same or lowerwrinkle recovery. In this case also the optimum condi-tion of processing would be considered at optimumwrinkle recovery with a higher retention of tensilestrength.

Fig. lOa illustrates the changes in dry wrinkle re-covery and the corresponding changes in per cent ret-ention of tensile strength with varying DMDHEUconcentrations in the presence of fixed catalyst, viz.MgCI2• A highly significant negative correlation (r =- 0.98) is obtained between per cent retention often-sile strength and resin concentration. The relation-ship may be represented as follows:

Tensile strength (retained) = 97.63-3.23 concen-tration(%).

SOM et al.:WRINKLE RESISTANCE AND TENSILE STRENGTH OF JUTE - BASED FABRICS

The relationship is non-linear (parabolic) in thecase of wrinkle recovery and per cent concentration,and is given below:Wrinkle recovery = 113.53 + 22.68 concentra-tion(%) - 0.88 (% concentrationl-,

The second degree correlation coefficient (r2) inthis case works out to 0.96, which is also highly signifi-cant at the 1% level. At around 9% concentration ofDMDHEU the two curves intersect, which thereforeappears to be the optimum value.

Fig. lOb shows the relationship between thewrinkle recovery angle and tensile strength reten-tion(%)-a non-linear parabolic trend. The figureshows that the wrinkle recovery angle first increaseswith decrease in tensile strength retention, attains amaximum value, and then decreases. The second de-gree correlation r2 comes out to be 0.84, which is how-ever found to be statistically significant at the 5% le-vel. The relationship may be represented as follows:Tensile strength retention(%) = 1967.36 - 16.21wrinkle recovery - 0.034 (wrinkle recoveryj'.

4 Summary and ConclusionsThe textile properties of jute cellulose made to

react with different types of N-methylol compoundsand inorganic salt catalysts were studied. The ammo-nium salt catalyst gives a more improved wrinkle re-covery angle in UF and MF finishes than metal salt ca-talysts which are effective in DMEU and DMDHEUfinishes. The wrinkle recovery angles for the jute fa-bric were highest in MgCl2 in both DMEU andDMDHEU finishes (2540 and 2600 respectively).ZnClz,Zn(N03)z and AlCl3 show intermediate results,the poorest catalyst being the FeCI3• DMDHEU givesa wrinkle recovery angle better than any other finish,and optimum results are obtained at 12% solid add-on in MgC12 catalyst. In general, wrinkle recoveryangle increases with increase in catalyst concentrationup to a level and further increase in concentrationcauses decrease in wrinkle recovery angle. The jutefabric gives the optimum wrinkle recovery angle at150cC curing temperature in 5 min curing period. Asthe concentration of the catalyst in the pad-bath in-creases, the tensile strength retention decreases.DMEU- and DMDHEU-treated jute fabric retaineda higher tensile strength than any other finish. Catal-ysts used in this study alone caused a higher tensilestrength loss than the crosslinked jute fabric. Thehigher loss in the tensile strength of jute fabric (than incotton fabric) due to crosslinking is attributed to the

smaller chain length of jute cellulose comparedwith cotton cellulose. The hemicellulose and lignincontaining a reduced number of - OHgroupsmaybecrosslinked through the resins and may contribute tofurther losses in physical properties. The wrinkle re-covery angle of jute fabric increases with the loweringof tensile strength irrespective of the resin-catalystsystem. The linear relationship is valid at the maxi-mum wrinkle recovery angle obtained, then at thesame wrinkle recovery angle, the tensile strength fur-ther decreases, and further acceleration of crosslink-ing reaction causes a simultaneous decrease, inwrinkle recovery angle and retained tensile strengthproperties of jute fabric; the overall relationship be-tween these two properties becomes parabolic. Thereason is mainly the poor elongation of the jute fibre.Balanced properties were obtained in the crosslink-ingreactionofjutefabricwithDMDHEU-MgC12andDMDHEU-ZnC12 finishes.

AcknowledgementThe authors would like to express their thanks to

Mr A Lahiri of Physics Division of UIRA for statisti-cal analysis, and Dr S R Ranganathan, Director, UI-RA, for his valuable criticism and interest during thestudy and permission to publish the paper.

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3,521,991 (1969).2 Das P C, Ghosh U K. J Text Assoc, June 1976.58.3 Naval L, Digma M, Suasba M and Obringuar B, Philipp Text

In! Dig, 7 (2) (1967) 1.4 Som N C, Roy A, Das P C and Bhattacharya H P, J Text Assoc,

March 1974,23.5 Sengupta A B and Radhakrishnan T, New ways to produce

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H U, Indian J Text Res, 1 (1976) 135.14 Reeves W A, Vail SL and FrickJ G(Jr), Text ResJ, 32 (1962)

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