Indian Journal of Fibre & Textile Research Vol. 27, June 2002, pp. 166-170
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Crease-resistant finishing of jute fabric using polycarboxylic acid ,
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'A)agchi " &
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SahaIndian Jute Industries' Research Association, 17 Taratola Road, Kolkata 700 088, lndia Received 3f'March 2000; revised received and accepted 14 February 200r
J he potentialities of jute fabric to develop wrinkle resistance through crosslinking with polycarboxylic acids, like citric acid and 1,2,3,4-butane tetracarboxylic acid (8 T C A), as an alternative to the conventional N-methylol compounds have been studied in the presence of phosphate catalyst by pad-dry-cure technique. It is observed that for jute fabrics, B T C A shows beller crease recovery than citric acid at all the concentrations studied. Citric acid finishing may, however, be used in the applications that do not require high crease recovery as it is less expensive. FTIR spectroscopy reveals the formation of ester crosslinks between jute fibre and polycarboxylic acid: '
Keywords Butane tetracarboxylic acid, Citric acid, Crease recovery angle, Jute
1 Introduction
Jute and jute-based fabrics are gatntng popularity in the domestic and international fields due to their ecofriendliness and biodegradability characteristics.
On the other hand, jute has limitations in crease recovery characteristics as it is stiff, coarse and has poor elongation. The crease-resistant property is very important for diversified use of jute goods. DMDHEU (10-12% add-on), although effective for imparting high level of crease resistance, suffers from the disad- vantages due to the formaldehyde release and strength loss. Non-formaldehyde cr6sslinking agents based on polycarboxylic acids, e.g. citric acid (C A) and 1,2,3,4-butane tetracarboxylic acid (B T C A), have already been used in cotton textiles as an alternative in ecosafe crease-resistant process. The first evidence that polycarboxylic acid imparts useful level of wrin- kle resistance to cotton was observed by Rowland ef al. 1.2
Welch3 used citric acid and BTCA crosslinking agents as an alternative to conventional N-methylol compounds in the presence of catalysts sodium hypo- phosphite / sodium phosphate. It was also observed that an esterification reaction takes place between the cellulosic material and the polycarboxylic acid, im- parting durable press properties to the fibre4,5. The curing process was conducted at high temperature 6
(150°-180°C). Jute is a lignocellulosic fibre which contains cellulose (58-62%), hemi-cellulose (20-24%)
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and lignin (12-14%) as main constituents as compared to cotton which is a cellulosic fibre. The potentialities of polycarboxylic acids, like BTCA and CA, as crosslinking agents for jute have not been studied thoroughl/. The present work was, therefore, aimed at studying the application of non-formaldehyde crosslinking agents like BTCA and CA on jute fabric in the presence of phosphate catalysts.
2 Materials and Methods
2.1 Materials
A decorative, plain weave, bleached (2% H202
owf) jute fabric having the following specifications was used for the study: Warp, 63 ends/dm (count 256 tex); weft, 55 ends/dm (count 256 tex); and fabric mass at 65% RH and 20°C, 275 g/m2.
Citric acid and 1,2,3,4-butane tetracarboxylic acid of reagent grade were used as crosslinking agents.
Sodium hypophosphite monohydrate (NaH2P02.H20), sodium dihydrogen(monobasic) phosphate (NaH2P04.2H20) and sodium monohydrogen (diba- sic) phosphate (Na2HP04) were used as catalysts. All these chemicals were of analytical grade.
2.2 Methods
The fabric was padded in a solution contatntng polycarboxylic acid, phospahte catalyst and non-ionic wetting agent (0.1 %) for the pad-dry-cure treatment.
The wet pick-up was adjusted to 100%. The padded fabric was dried at 80°C, cured at 140°-160°C for 5 min, washed with water and finally dried.
Crease recovery angle was measured by the Mon- santo crease recovery tester in accordance with
BAGCHI & SAHA: CREASE-RESISTANT FINISHING OF JUTE FABRIC 167
Table I-Effect of catalyst concentration and curing temperature on wrinkle recovery and tensile strength of jute fabrics treated with 10%(owl) citric acid and 8% (owl) BTCA
Cross-linking agent Catalyst
Citric acid Nil
NaH2P04·2H2O
Na2HP04
NaH2P02 .. H2O
BTCA Nil
NaH2P04 .. 2H2O
Na2HP04
NaH2P02·H2O
Catalyst conc.
%
0 2 4 6 2 4 6 2 4 6 0 2 4 6 2 4 6 2 4 6 Dry crease recovery angle of untreated jute ( W+F), 150u ASTM-D-1295-67. The loss in tensile strength (%) of the treated fabric was measured on an Instron machine (U.K.) using the ravelled strip method.
FfIR spectra of treated jute were obtained using the KBr pellet technique on a Nicolet FfIR spectro- photometer (Model: MAGNA-IR 550). Thermal char- acteristics were measured using the thermogravimet- ric analyser on a Mettler TG 50.
3 Results and Discussion
The effect imparted by the citric acid and BTCA crosslinking agents on the crease recovery and tensile strength of jute fabric is shown in Tables I and 2. The degree of crease recovery imparted to jute fabric by a crosslinking agent is related to the nature and concen- tration of crosslinking agent, catalyst and curing con- ditions. The results show wide variation in crease re- covery angle with different polycarboxylic acid- catalyst systems. The dry crease recovery angle (W + F) varies from 1800 to 2600•
3.1 Citrie Acid Treatment
Table I shows the effects of different catalysts, their concentrations and curing conditions on crease recovery and per cent loss in tensile strength of jute
Dry crease recovery angle(W+F), deg
Loss in tensile strength
%
140aC 150aC 160aC
170 172 170 12.0 18.1 20.9
180 198 192 18.4 29.3 30.7
222 240 238 36.0 39.9 46.0
226 238 240 37.6 43.0 48.1
176 192 190 15.4 27.0 28.8
220 232 230 32.1 35.0 40.1
221 230 232 34.1 38.4 40.1
188 204 206 17.9 29.0 30.1
230 240 240 35.5 38.0 44.9
228 244 242 37.0 41.9 46.5
178 190 192 12.8 15.4 . 18.2
194 212 206 21.9 32.0 33.9
235 254 252 37.9 41.9 49.9
238 250 252 38.9 43.9 51.4
190 209 204 20.4 29.9 32.1
234 250 248 36.6 40.2 49.2
236 248 250 37.1 42.0 50.0
200 222 220 20.2 29.9 32.6
240 258 257 36.0 40.9 49.0
241 256 258 37.9 41.9 50.4
Table 2- Effect of citric acid and BTCA treatments on crease recovery and tensile strength using NaH2P02.H20 catalyst Polycarboxylic
acid
BTCA
CA
Acid conc., % (owl)
12 10 8 6 12 10 8 6
Dry crease recovery angle
(W+F) deg 262 264 260 232 244 242 210 204 Acid/catalyst molar ratio, I : 1.5
Curing conditions, 150aC for 5 min
Loss in tensile strength
%
48.6 45.9 40.8 28.0 47.0 46.0 39.8 28.5
fabrics treated with citric acid (10% owf'). It is observed that in case of all the three catalysts (sodium hypophosphite, sodium dihydrogen phosphate and sodium monohydrogen phosphate), the crease recovery increases as the catalyst concentration varies from 2% to 6% and reaches a maximum value at 4%
catalyst concentration. However, more strength loss
168 INDIAN J. FIBRE TEXT. RES., JUNE 2002
occurs without further significant improvement in crease recovery beyond 4% catalyst concentration.
Curing was found to be optimum at ISO°C for S min in all the experiments. Of the three catalysts used, sodium hypophosphite gives the best result. Table 1 shows that the optimum crease recovery value obtained for the citric acid crosslinked jute fabric IS
moderate (230°-240°).
3.2 BTCA Treatment
The effects of BTCA (8% o.w.f.) on crease recov- ery and tensile strength of jute fabric at different cata- lyst concentrations and curing temperatures are shown in Table I. Here also, each catalyst was chosen at three different concentrations (2,4 and 6%) and cured at three different temperatures (140°, 150°, l60°C) for 5 min. lt is observed that at 2% catalyst concentration, the crease recovery value (W+F) is around 200° . At 4% catalyst concentration, the crease recovery value (W+F) increases substantially from 250° to 258° with the increase in temperature and at 6% catalyst concen- tration, no further improvement in crease recovery angle is observed. The strength loss is found to in- crease with the increase in catalyst concentration and is maximum at 6% catalyst concentration for all the catalysts studied at three different curing tempera- tures. Of the three curing temperatures used, 150°C is found to be the optimum for all the catalysts. It is also evident from Table 1 that the sodium hypophosphite gives the best results followed by sodium dihydrogen phosphate and sodium monohydrogen phosphate.
3.3 Comparison between BTCA and Citric Acid
Table 2 shows that at 8% concentration, BTCA provides the optimal crease recovery whereas citric acid at 10% concentration gi ves the optimal crease recovery for sodium hypophosphite monohydrate at a particular concentration. With the further increase in concentration, no further improvement in crease recovery is observed, rather more strength loss occurs.
It is also observed that the BTCA is a better anti- crease agent for jute fabric because it imparts maxi- mum crease recovery value of 264° vis-a-vis 244° in case of citric acid. The strength loss is around 30-40%
at optimum condition for both the polycarboxylic acids. The higher crease recovery value imparted by BTCA over citric acid is possibly due to the higher number of functional groups which form more crosslinks with the constituents of jute fibre, giving higher crease recovery.
Weight gain -.
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Weight loss. mgls
Fig. I- Thermogram of grey jute fabric Weight gain _ .•
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Fig. 2- Thermogram of BTCA-treared jute fabric
Table 3 - Results of thermogravimetric analysis of untreated and polycarboxylic acid-treated jute in nitrogen atmosphere
Sample Major WI. lass Residue left
degradation % at 550°C
tcmperature, °C %
Raw jute 355.7 77.3 11,69
Citric acid -treated 347.5 69.6 19.53 jute
BTCA-trealed jute 345.0 68.4 21.48
3.4 Thermal Analysis of Untreated and Treated Jute
The DTG curve of grey jute fabric in nitrogen is shown in Fig. 1. The initial weight loss below 100°C (peak at 49°C) is due to the loss in moisture which is about 8.79% of the sample. The major degradation starts at 142°C and ends at S39°C with maximum peak temperature at 3S6°C, resulting in weight loss of 77%. This is attributable to the degradation of cellu- lose and hemicellulose8. The residue left at 550°C is 11.7% (Table 3).
The DTG curve of BTCA-treated jute fabric is shown in Fig. 2. The initial weight loss below 100°C
BAGCHI & SAHA: CREASE-RESISTANT FINISHING OF JUTE FABRIC 169
(peak at 43.rC) is due to the moisture loss (6.94%).
This is significantly lower than that of grey jute due to the crosslinking of fabric with BTCA. Moisture regain of fabric decreases due to the blocking of ac- cessible hydroxyl groups in jute. The major decomposition temperature, therefore, shifts towards the lower side (peak at 345°C) as compared to the untreated grey jute, indicating the change in chemical property. The residue at 550°C is also much higher (21.48%) as compared to that in untreated fabric. This is due to the crosslinking of cellulose and hemicellulose chains through BTCA, resulting in production of less volatiles.
The DTG curve of citric acid treated jute fabric is shown in Fig. 3. The initial degradation temperature (peak at 43.7°C), which is caused by moisture evapo- ration, is around 7.65%. The major decomposition occurs at 347.5°C and final residue is 19.5%. This may be due to the reason as discussed above.
As BTCA is a more powerful crosslinking agent than citric acid due to the more number of functional groups, the degree of crosslinking is more in case of BTCA and this lowers the moisture regain and in- creases the residue left in case of BTCA-treated jute.
3.5 FTIR Studies
Several studies on the FfIR analysis of crosslink- ing reactions of citric acid and BTCA on cotton, which show the formation of ester links between the hydroxyl groups of cellulose and the carboxyl groups of polycarboxylic acids, have already been reported9•11
•
FfIR spectra of bleached, citric acid-treated and BTCA-treated bleached jute fabrics are shown in Fig. 4.
Bleached jute fabric shows absorption in the region of 3012-3729 cm-I due to the hydroxyl group and 1697- 1822 cm -I due to the ester group. Citric acid-treated and BTCA-treated bleached jute fabrics show de-
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Fig 3 -Thermogram of CA-treated jute fabric
crease and increase in the absorption in the regions 3012-3729 cm-I and 1697-1822 cm-I respectively as compared to that in the control bleached jute fabric.
The area ratio of the hydroxyl/carbonyl groups is found to be 44.92, 18.93 and 14.17 in case of
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Fig. 4 - FTIR spectra of (a) bleached jute, (b) citric acid crosslinked jute, (c) BTCA-crosslinked jute, and (d) BTCA- treated jute (saponified)
Tablc 4-FTIR study on polycarboxylic acid-treated jute fabric Sample
Bleached jute Citric acid-
treated jute (10% owf)
I3TCA-treateci jute (8% owf)
Area of absorp- Area of absorp- tion duc to hy- tion due to car- droxyl group bony 1 of ester (3012-3729 and carboxyl cm-I) (1697-1822
cm-I)
30.499 0.679
23.383 1.235
21.918 1.546
Area ratio (-OH/CO of ester & car-
boxyl)
44.92 18.93
14.17
170 INDIAN J. FIBRE TEXT. RES., JUNE 2002
bleached, cltnc acid-treated and BTCA-treated bleached jute fabrics respectively (Table 4). This may be due to the fact that the crosslinking agents citric acid and BTCA form ester linkage with hydroxyl groups of cellulose and hemicellulose present in jute.
When jute is boiled with 0.1 N alkali, the absorption due to the ester disappears due to the hydrolysis of ester linkage. This indirectly proves that the ester group is formed by polycarboxylic acid crosslinking of jute. This can be observed from the FfIR spectrum of BTCA-treated saponified jute (Fig. 4).
4 Conclusions
As formaldehyde-free durable press finishing agents for jute fabric, the citric acid and 1,2,3,4- butane tetracarboxylic acid can be used with certain inorganic salts of phosphorous containing acids to produce acceptable crease- resistant properties. Citric acid and BTCA react readily with jute at an elevated temperature. The curing condition must be wisely chosen to reduce yellowing of jute as jute becomes yellower above 160°C. BTCA- based finish gives bet- ter crease recovery property for jute but it is expen- sive. Citric acid finishing with proper catalyst may
find a place in application that does not require high crease recovery value as it is less expensive.
Acknowledgement
The authors are thankful to Dr. K. Jayachandran, Director, IJIRA, for his interest during the study.
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