Indian Journal of Fibre & Textile ResearchVol. 17, March 1992, pp. 27-31

Durability of modal and its blends: Part IT

R VatsalaDepartment of Textiles and Clothing, College of Home Science, A P Agricultural University,

Hyderabad 500004, Indiaand

V SubramaniamTextile Technology Department, A C College of Technology, Anna University, Madras 600 025, India

Received 16 January 1991; revised received 16 September 1991; accepted 1 October 1991

Increase in modal (Md) content in Md blended fabrics lowers the flex and flat abrasion resistance inboth dry and wet conditions, which are further lowered with increasing level of laundering. The wear lifeof Md blends increases with increase in polyester or cotton content, as assessed by wear index.

Keywords: Flat abrasion resistance, Flex abrasion resistance, Wear index

1 IntroductionThe durability of a fabric is partly dependent on

its resistance to abrasion when the abrading force isacting on its flat surface as well as when the fabric isrepeatedly bent by the flexing action. These kinds ofabrasion are found more in the laundering processbut can also be found in use of fabrics.

Fabric durability in terms of dimensional stability,breaking strength and tear strength has been dis-cussed earlier'. These properties or the changes inthese properties due to laundering would be mea-ningful to an educated consumer. But their useful-ness to a lay and uneducated consumer can still bequestionable. Therefore, in the present study, theabrasion resistance of modal (Md) and its blendswith polyester (PE) and cotton (C) has been studiedand the abrasion resistance together with the dimen-sional stability and breaking and tear strengths as-sessed earlier! have been utilized to express the ac-tual wear life of fabrics in the form of wear index(WI) following the Stoll's method". Wear index is anumerical figure which takes into consideration thewearing quality of a fabric derived from certain spe-cific wear tests as compared with actual wear, basedon certain combat course study.

2 Materials and MethodsSix Md/PE blends (3 shirtings A - C and 3 suit-

ings D - F), four Md/C blends (2 shirtings G & Hand 2 suitings I & J), a 100% modal saree (L) and a100% modal suiting (K) were subjected to nil, 10,20and 30 machine laundering using an anionic deter-

gent of grade-I. Fourteen Md/C blends (7 shirtingsM - S and 7 suitings T - Z) were specially wovenand tested. The construction particulars of test fa-brics were same as reported earlier' .

2.1 WashingThe details of the washing machine and washing

process have been reported earlier! .

2.2 Flat Abrasion Resistancethe flat abrasion resistance of the test fabrics was

assessed according to the BSI method '. The abra-dant carborundum GN 120 was used. Multi-direc-tional abrasion was effected till the formation of firsthole. The number of cycles indicated at the end-point was noted, as it can be considered to corre-.spond with an effect of wear similar to the kind ofbreakdown that might occur during service",

2.3 Flex Abrasion ResistanceFlex abrasion is very sensitive to the effect of sur-

face or internal lubrication. Sharma et al:5.6 found ahigh correlation between flex abrasion resistanceand actual wear. As the simulation of actual wear,involving stress, strain, laundering, dry cleaning andcreasing, is a formidable task, the abrasion resist-ance of a fabric could serve as an indicator of wearlife, though the results are qualitative in nature forcomparative assessment". The testing of flex abra-sion resistance is much faster and reliable than thatof flat abrasion resistance.

The flex abrasion resistance of samples A - L was

28 INDIAN 1.FIBRE TEXT. RES., MARCH 1992

assessed by the universal abrasion tester as per theASTM method". The reciprocal movement was 120rpm. The abradant used was water-proof carborun-dum No. 600. A constant tension load of 19.02 Nand a pressure load of 1.4715 N were applied basedon the preliminary tests conducted on the test fa-brics. The number of cycles required ·for fabric fai-lure was considered as the end point.

2.4 Wear IndexWear index (WI) was assessed following the Stoll's

method and using the available test data. The deve-lopment of this index on the basis of weighted con-sideration of the various lab-wear components in-volved conversion of absolute to relative valuessuch as percentage of the values of a combination ofproperties which correspond to those predominantin combact course and upon the application of thewear composition deducted by salvage studies. Inaccordance with the results of the previous investig-ations=!", Stoll used the following formula for theprediction of wear index.Wear index (WI) = 0.50 of flex abrasion + 0.20 of flat

abrasion + 0.30 of tear resistance

where the flex abrasion was assessed warp-wise withthe face of the fabric, flat abrasion was multi-direc-tional up to the formation of the first visible holeand the tear strength was the mean of warp and weftmean strengths.

3 Results and Discussion

3.1 Flat Abrasion ResistanceThe retained flat abrasion resistance of the test fa-

brics is given in Tables 1 and 2 and Fig. 1. With theincreasing level of laundering, the retained abrasionresistance decreases both in Md/PE and Mdle'blends which is expected of textiles in general. Han-dy et al:" and Elmasri et a/.12 also made a similar ob-servation. The retention of flat abrasion resistancein case of E and F and increase in case of I can be at-tributed to the use of two-fold yams and the lubri-cating effect of silicon finish'? which facilitates theyam mobility under the abrading force. The highflat abrasion resistance of sample N could be due tothe comparatively higher fabric count as also report-ed by Taylor!~.

Table 2 and Fig. 2 show that the increase in Mdcontent lowers the abrasion resistance. The sequ-ence of damage is probably the damage to thecrowns of interlacings followed by stripping of suc-cessive fibrillar layers due to the shear force deve-loped during rubbing'{. The Md fibres wear out firstfollowed by the second stronger fibre component.This might be due to the variation in the degree of

Table I=-Effect of laundering on flat abrasion resistance of testfabrics

Fabric Flat abrasion resistance (Cycles to rupture)

UL

Modal/Polyester

A 68

B 301

C 347

D 248

E 797

F 355

Modal/Cotton

G 44

H 164

I

J

Modal

K

L

264139

lOL 20L 30L

36- 23- 21"(-47.06) (-66.18) ( -66.18)

166- 127a 95"( -44.85) (- 57.81) (-68.44)

161a 157a 82"(- 53.60) ( -54.60) ( -76.37)

118"(- 52.42)

749( -6.02)

359(+ 1.13)

50- 32a 25-( -13.64) (27.27) (- 43.18)

155 122a 100a

( -7.19) (- 26.95) (-40.12)

76a

(-45.33)

103 48(- 53.40)

8a

(- 27.27)11 8-

(- 27.27)lOa

( -9.09)

a'1' values significant at 0.01% level.The values in parentheses indicate % difference in the propertyrelative to UL.

polymerization of the two components. Significantchange in this property was observed in almost allthe fabrics.

3.1.1 Effect of Moisture on Flat Abrasion ResistanceThough a similar trend is observed in the wet tests

(Table 2), there is an overall fall in the flat abrasionresistance from that in the conditioned tests; 16:84Md/C tops all the others. The flat abrasion resistanceof the blend 16:84 (Sample N) is 7.6% of cotton inthe conditioned state and 10.3% in the wet state.Stoll indicated that the mean of one fabric must ex-ceed the grand average by 10% if there is a signifi-cant difference in abrasion resistance. On this basis,the values of all the fabrics, except 100% Md, inTable 2 are significantly different from each other.

VATSALA & SUBRAMANIAM: DURABILITY OF MODAL AND ITS BLENDS 29

Table 2-Flat abrasion resistance of conditioned and wettest fabrics

Fabric Flat abrasion resistance % Difference(Cycles to rupture)

Conditioned Wet

Modal/Cotton

M 250.00 155.00 -38.00(100.00) (100.00)

N 19.00 16.00 -15.99(7.60) (10.32)

0 32.00 25.00 -21.88(12.80) (16.13)

p 55.00 41.00 -25.45(22.00) (26.45)

Q 82.00 47.00 -42.68(32.80) (30.32)

R 137.00 91.00 - 33.88(54.80) (58.71)

S 214.00 130.00 - 39.25(85.60) (83.87)

Values in parentheses are relative to 100% cotton (Sample M)

300~.2g- 260~.2IJl 220QJ

u>-UQJ~ 180uc0-:n 140IJlQJ~c 1000IJl0....0 600

0~ 20

UL

-lC-52Md:48PE (SampleS)

-0- 65Md:35C (Sc rnple l+)-6- 52Md:48C (SampleG)-0- 35Md:65PE(SampleA)

~_--t;ra ------6--10L 20L 30LLevel of laundering

Fig. I-Effect of laundering on flat abrasion resistance

3.1.2 Flex Abrasion Resistance as an Indicator of Wear LifeIncrease in flex abrasion resistance with increase

in PE or cotton content (Table 3, Fig. 3) on thewhole indicates low abrasion resistance of Md. Theincreased flex abrasion resistance of MdlPE overMd/C could be due to the high DP of PE. Further,an examination of the abraded area during testingshowed marked predominance of PE in the case ofMdlPE blends which confirms the above assump-tion. All fabrics, irrespective of their blend composi-

800ClJ~::J0. 700::J~0-;;; 600~u·>-u 500..ClJuc.9 400III'ViClJ~

300 Ic0 0IIIa~ 200.Daau: 100

E -x-Md:PE(UL)E l> -6- Md :PE (30)

-Q-Md :C (UL)

o~ __~ __~~~~ __~~~~o 20 40 60 80Modal content)o,o

Fig. 2-Effect of modal content on flat abrasion resistance

100~~~_~~_~_~~_~_~~Md 0 20 40 60 80 100

p~ or C 100 60 60 40 20 0

~ 800:>a.:>~.2 700IJl~Uc-, 600uOJ~uC0-:n 500iii~c0 400III

~.00 300xOJu,

200

oE-0- Md :C(UL)

-&-Md:PE(UL)--lC-- Md :C(30L)--h-- Md:PE(30L)

\,\ ,

\ ,It..... \ ,-- ,

-~-_hJ'- --~J - _

Fig. 3-Effect of modal content on flex abrasion resistance

Blend composition, ./.

tion, registered a significant drop in flex abrasion cy-cles with progressive level of laundering as shown inFig. 4. This could be due to the abrasive action ofthe washing process. A significant drop in this prop-erty is also observed in suitings E, F and K at UL le-

30 INDIAN 1. FIBRE TEXT. RES., MARCH 1992

Table 3-Effect of laundering of flex abrasion resistance of testfabrics

Fabric Flex abrasion resistance (Cycles to rupture)

UL IOL 20L 30LModal/Polyester

A 69 61b 64 61b(- 11.59) ( -7.25) (11.59)

B 217 178b 183b 186b( -17.97) ( -15.67) (- 14.29)

C 221 219 206 1~lb( -9.90) ( -0.07) ( -18.10)

D 162 151( -6.79)

E 858 706( -17.72)

F 470 445( -5.32)

Modal/Cotton

G 107 94a 107 93b( -12.15) (0) ( -13.08)

H 257 180b 153b 170b(- 29.96) (-40.47) (- 33.85)

483 344(- 28.78)

J 231 253( +9.52)

ModalK 185 198

(+7.03)L 45 62b 57b 46

(+ 37.78) (+ 26.67) (+ 2.22)

"t' values significant at 0.05% level.b<t'values significant at 0.01 % level.Values in parentheses indicate % difference in the property rela-tive to UL.

vel. As they have almost similar geometrical para-meters, the variation in their flex abrasion resist-ance could not only be due to the variation in overallMd content but also due to the variation in the Mdcontent of wefts which are highly exposed to thiskind of abrasion.

From the above discussion on flat and flex abra-sion resistance and the tear strength reported ealier 'it is evident that these three properties decreasewith the decrease in PE or cotton content in the Mdblends. Rangan et al.15 reported a similar trend inthe case of polynosic/cotton (PN/C) blends whileBansal et al." reported a similar finding in the tearstrength and abrasion resistance of PN/C blends.Thus, there could be some inter-relationship be-tween these properties. Therefore, an assessment of

- .-65 Md: 35C (Sample H)--~ -65Md:35PE(Sample C )-x-52Md:48PE(Sample B )-6-52Md:48C (Sample G)

21/1GJu

is 190

GJ

~ 170o1/1.~ 150~co 1301/1o~-g 110)(GJ

IJ.. 90L-L_ ~L_ L_ ~~o UL 30L10L 20L

Level of laundering

Fig. 4-Effect of laundering on flex abrasion resistance

Table 4-Effect of laundering on wear index

Fabric Wear index

UL 10L 30L20L

Modal/Polyester

A 49.39B 145.42

C 149.84D 109.60E 545.90F 298.71

41115140

43117131

4111611397

452

283

Modal/CottonGHI

J

67.01164.92181.33

147.50

60115

6798

58107

157

ModalKL

118.29

33.82 36

1242940

wear index, which is the weighted combination ofsurface, flex abrasion resistance and tear strength,for indicating the performance quality of blends wasattempted.

3.2 Wear Index of BlendsMd/PE blends E, F and K with identical con-

struction parameters show a marked decrease intheir wear index with increase in PE content (Table4); E tops the three followed by F and K. Md/C suit-

• VATSALA & SUBRAMANIAM: DURABILITY OF MODAL AND ITS BLENDS 31

ings I, J and K with identical constructions alsoshow a similar trend. This is in agreement with thefindings pertaining to the tensile, tear and abrasionresistance of unwashed samples M - S of similarconstructions.

The WI of Md/PE and Md/C blends depends onthe percentage of PE or cotton content in the blendsin general as sample E which has a higher PE con-tent compared to F and I compared to J also scorehigher WI. Their constructions are more or lesssame but for the difference in their thickness. The fa-bric thickness of samples E and I are significantlydifferent from those of F & K and J & K respectivelyand probably this is also responsible for the differ-ence in their wear index in addition to the expectedPE or cotton content of the blend. Thus, 100% Mdsuiting has the least wear life followed by 84:16 and16:84 Md/C blends and 67:33 and 33:67 MdlPEblends, the latter having the highest WI.

Though the WI of test fabrics M - S could not beassessed due to .their paucity, the Md/C blend N(16:84) appears to be the best alround performerand it is likely to be so even after multiple launder-ings like the sample I, which also has low Md con-tent and yet tops the three fabrics I, J and K after re-peated laundering.

4 ConclusionIncrease in Md content lowers the flat and flex

abrasion resistance of Md/PE and Md/C blends.The flex abrasion resistance of MdlPE and Md/Cblends increases with Increase in PE or cotton con-

tent. Indices such as wear index can serve as an use-ful indicator of the wear life of fabrics to a laymanwho knows nothing about the fabric durability evenafter testing the fabrics. The higher the WI the betterthe overall durability of fabrics.

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