Indian Journal of Textile ResearchVoL 9, September 1984, pp. 90-94

Performance Properties of Terry Towels Made from Open-endand Ring-spun Yarns

N M SWANI, P K HARI & R ANANDJIWALADepartment of Textile Technology, Indian Institute of Technology, New Delhi 110016

/"/': Received 8 May 1984; accepted 9 July 1984

/' There is no difference in the water absorption rate of ring-spun and open-end (OE) terry towels but the maximumabsorption for OE towels is better than for-ring-spun towels at lower fabric density and for comparable fabric weight. Higherpile length and fabric weight favour greater water absorption but only high pile density increases the water absorption rate.The abrasion resistance of ring towels is better than that of OE towels in both dry and wet states. The abrasion resistance offabrics is significantly lowered on wetting. Longer pile length and moderate pile density contribute to imparting maximumabrasion resistance.

.»

Water absorption and abrasion resistance are the mostimportant performance properties of terry towels,Studies on open-end (OE) yarns show that thesepossess better water absorption and abrasionresistance than ring-spun (R) yarns, Except for Lord'swork 1, there is not much work done in this area, Hencethe present work.

Experimental ProcedureFabrics- Three pick terry towels were made from

OE and ring-spun cotton yarns. Yarns of 20 Ne (29.5tex) were spun on the ring frame and a rotor spinningmachine(BD 200). These yarns were doubled and usedfor ground and pile warp, and 20 Ne single yarns wereused in the weft direction. The properties of the yarnsare given in Table 1. Different fabrics were made byvarying the pile-to-ground ratio (PR) (5.0,4.5,4,0) andends/picks per in (52/56, 48/52, 44/48, 40/44). Loomstate fabrics were scoured to remove natural fats andwaxes.

Water absorption-Several methods? -8 have beentried for measuring the water absorption of towels.Carry? has shown that two test methods, viz. porous

Table I-Properties of Yarns

OE RingSingle yarnCount (Ne)Count strength productBreaking strength, g/texBreaking elongation, %Turns/inDouble yarnCount (Ne)Count strength productTurns/in

20.812768.37.320

20.7191013.56.2

20.5

2/20.8161114.8

2/20.7200614.9

90

plate and sliding block, have potential for measuringthe moisture absorbency of terry towels. In the presentwork, the porous plate method as suggested byJackson and Roper" has been used to simulate waterabsorption from a wet surface, the length of themeasuring tube being increased to 320 em,

An apparatus as shown in Fig. I was assembled.Distilled water was filled from the reservoir R into theburette U using a two-way stop cock A. For a givenposition of the funnel F containing the porous plate P,water was filled in the horizontal measuring tube Twith stop cocks Band E open. Stop cock C helped tobring water in U at the level ofT by draining. Underthis condition with the meniscus in the measuring tubeat rest and the system in equilibrium, the stop cocks Aand C were closed. The cloth sample, cut to the size ofthe porous plate, was placed above it, with a slightpressure applied by a bag containing fine lead shot. Byopening the stop cocks Band E, the volume of waterabsorbed can be determined by the movement of themeniscus in the tube T.

u

Fig. I-Absorbency apparatus

SWANI et al.: PERFORMANCE OF TERRY TOWELS

To obtain the absolute values of absorption rate, itwas necessary to determine the plate resistance (R;>.The plate resistance was determined by studying thewater flow rate (I) at various heads (E), that is, thedifference in the levels of the measuring tube in relationto the porous plate as shown in Fig. 2. The relationshipbetween E and I can be expressed by E =RpI. The valueof plate resistance, thus determined, was 52.2 em -2s -1.

By measuring the rates of flow with the sample onthe plate at two different levels, one at a negative headof 6 em and the other at zero head, the combinedresistance of plate and cloth (Rpe) can be determined,giving the value of cloth resistance R; = Rpe - Rp.

The absolute value of flow rate (Ie) at zero headthrough cloth alone was obtained from the relationRefe = Rpc Ipc·

Results and DiscussionWater Absorption

Yarn wicking-Water absorption by yarn wasstudied by measuring the wicking height with respectto time; a typical curve is shown in Fig. 3 for ring andOE yarns. The wicking height and the rate of wickingare higher for the OE yarn. This agrees with the findingof Lord 1, who explained with a simple model thatwicking height varies directly with the packing factor.OE yarns have a dense core and are expected to give ahigher wicking height than ring yarns.

Fabric absorbency-A typical fabric absorbencycurve is shown in Fig. 4, which is similar to the yarnwicking curve shown in Fig. 3. Initially, it is a straightline and gives maximum absorption rate and thenflattens out. The straight portion was found to extendfrom 20 to 70% of maximum absorption and whenextrapolated gave an intercept on the time axis. This

0.8,-----------------,

0.&

.•iu

~~ 0.4..J•..•..o•••~a:

0.2

Fig. 2-Calibration of plate resistance

indicates an initial time lag before the samples begin toabsorb water at maximum absorption rate. This is inagreement with the findings of Jackson and Roper"and Buras et al.7. Two parameters, viz. maximumabsorption rate and maximum absorption, wereobtained from the curve for different fabrics. These aregiven in Table 2 along with the absolute maximumabsorption rates calculated on the basis of absorpticrate at two heads.

Absorption rate-Table 2 shows that absorptionrate is maximum for dense fabrics and it does notdepend on pile-to-ground ratio. Fig. 5, in whichabsorption rate is plotted against pile density (piles!in2) for ring and OE fabrics irrespective of pile length,shows that the absorption rate increases initiallyslowly and later rapidly with increase in pile density.

Terry pile yarns make contact with water on theporous plate surface and act as capillaries for carryingwater to the ground fabric. Absorption rate is affectedby the number and size of the capillaries. Increased piledensity gives increased independent capillaries whichhelp increase absorption rate but reduce the inter-pileand inter-yarn capillary size. Accordjng to the surfacetension equation, the height of water in a column is

6o OE• Ring

E 4u....:I:

~~ 2ui

TIME, min

Fig. 3~Yarn wicking

MOJeimul'ft Absorp~

Fig. 4-A typical fabric absorbency curve

91

INDIAN J. TEXT. RES., VOL. 9, SEPTEMBER 1984

Table·2-Fabric Absorbency

Nominal Fabric Actual Pile Sample Free yarn Pile Absolute Max.ends/picks pile-ground density weight length length max. flow absorption

per in ratio piles/in? g in/in 2 in rate mlcm3/s

48 x 52 OE 4.89 263 2.52 76 0.290 0.50 12.1Ring 4.87 273 2.67 79 0.290 0.53 12.9OE 4.42 267 2.29 69 0.261 0.48 11.1Ring 4.22 270 2.37 70 0.260 0.46 10.4OE 3.59 268 2.17 57 0.212 0.52 9.4Ring 3.88 275 2.21 64 0.233 0.54 9.4

44x48 OE 4.9 238 2.33 75 0.316 0.32 1l.6Ring 4.85 237 2.44 73 0.308 0.25 11.5OE 4.2 232 2.22 62 0.266 0.33 10.0Ring 4.3 242 2.67 65 0.268 0.32 10.8OE 4.02 231 2.17 59 0.256 0.33 9.3Ring 4.09 236 2.25 62 0.262 0.35 10.0

4Ox44 OE 4.84 190 2.31 64 0.335 0.25 1l.8Ring 4.90 198 2.30 69 0.348 0.24 10.3OE 4.49 196 2.30 61 0.311 0.30 1l.2Ring 4.57 205 2.29 66 0.322 0.32 10.1OE 3.98 197 2.20 56 0.282 0.28 10.3Ring 4.22 202 2.20 60 0.296 0.26 9.6

End/in x picks/inPile density

Ends/repeat x picks/repeat

Free yarn length = pile density x pile length

~Eu·0.5

UJt-

8 I IS~0:--~-~6~0:---L--7~0~--'--~80

AVAILABLE FPEE YARN, in/in2

Fig. 6-Effect of free yarn length on maximum absorption

to-ground ratio for any given sett. It was not possibleto know the effect of pile density at constant pile ratioon maximum absorption, so the product of pile densityand pile length represented by available free yarn wasplotted against maximum absorption (Fig. 6). Thisshows an interesting direct relationship betweenavailable free yarn and maximum absorption for OEand ring fabrics (correlation coefficient, 0.8859). Thescatter in the figure could be because ground structure,which also absorbs water, was not considered.

Pile length, pile density and fabric sett affect the

SWANI et at.: PERFORMANCE OF TERRY TOWELS

fabric weight, so maximum absorption was plottedagainst the sample weight (Fig. 7). The maximumabsorption increases initially rapidly and then tends tolevel off with increase in fabric weight. The maximumabsorption of OE fabrics is better than that of ringfabrics except at the highest fabric weightcorresponding to dense fabrics. This may be due tobetter utilization of the bulk of OE yarn for waterabsorption. The correlation coefficients betweenfabric weight and maximum absorption for OE andring fabrics were 0.97 and 0.99 respectively and thelower combined correlation 0.90 reinforces thedifference between OE and ring fabric behaviours.

The dependence of maximum absorption on pilelength is observed in Fig. 6. Therefore, a relationshipbetween maximum absorption and the product offabric weight and pile ratio would explain the effect ofsample weight on maximum absorption normalized topile ratio. Interestingly, the above relationship is linear(correlation coefficient, 0.942) over the range offabricsstudied as shown in Fig. 8. This is a useful relation and

13.0o DE Fabric• Ring Fabric

12.0

E

s~~ 11.0:j~:>:

10.0

og.O~ __ L-~~ __ ~~~I~~ __ ~~~

2.0 2.2 2.4 2.6SIIMPLE WEIGHT,9

Fig. 7~EfTect 01 sample weight on maximum absorption

16~---------------------------,

x..•:0:

o R mg Fabric00 E Fabric

14

Ez~ 12

2lv>II).•• 10

o

4 10

W. P R12 14 16

Fig. 8~Dependence of maximum absorption on the product offabric weight and pile ratio

suggests that an increase in maximum absorption maybe obtained either by an increase in fabric weight or byincreasing the pile ratio.

Abrasion Resistance

The abrasion resistances of the dry and wet fabricsare given in Table 3. The abrasion resistance is plottedagainst pile density for different pile ratios in Fig. 9.The abrasion resistance increases to a maximum withincrease in pile density and then decreases in somecases (for higher pile ratio) with further increase in piledensity. The abrasion resistance is greater for higherpile ratio. Increase in pile density offers more load-bearing piles, and higher pile ratio gives longer pile andmore fabric coverage. Therefore, both these improvethe abrasion resistance but the reduced mobility of thepile yarn beyond an optimum pile density will reducethe abrasion resistance. The mobility of OE yarn(being bulkier) will be affected even for lower pileratios.

Fig. 9 also shows lower abrasion resistance for wetfabrics. This agrees with the findings of Deflruy'".Water swells the fibre/yarn and because of itslubricating effect it facilitates easy pull-out of the fibresfrom the yarn matrix and the yarn swelling affects theflexibility of the pile yarn. Both these explain the lowerabrasion resistance of wet fabrics.

Table 3-Abrasion ResistanceNominal Fabric

ends/picks

per in

Nominalpile-

groundratio

Actualpile-

densitypiles/in"

52 x 56 OE 5.0 300Ring 316OE 4.5 302Ring 318OE 4 283Ring 312OE 5 263Ring 273OE 4.5 267Ring 270OE 4 268Ring 275OE 5 238Ring 237OE 4.5 232Ring 242OE 4 231Ring 236OE 5 190Ring 198OE 4.5 196Ring 205OE 4 197Ring 202

48 x 52

44x48

4Ox44

Abrasion, cycles

Dry Wet

577 459566 437375 278542 409356 277522 364608 404595 489418 368404 383338 304366 329388 357451 378298 260370 313282 241332 278338 268373 296373 236308 285271 227278 239

93

INDIAN J. TEXT. RES., VOL. 9, SEPTEMBER 1984

L520

VI 44li........•u>-u

z 360CIVi-c:li 280-c

200190

Dry abrasion

Ring/

""'Wet abrasion

600

520

Vl....440 ;j

>-w

---:: ~I ~- /Dry nbrcsien~ OE

......••Wet nbrusien

360 ~VI-c0::•••280 -c

200

Fig. 9 shows that the dry and wet abrasionresistances of ring fabrics are better than those of OEfabrics (except for one fabric). At equal twist levels, OEyarn is bulkier, less cohesive andit appeared to yield toabrasive action in spite of wrapper fibres, The tearing-out action and fibre plucking take longer in ring fabricsbecause of firm binding of fibres in the helicalconfiguration.

ConclusionsThere is no significant difference in the water

absorption rates of ring and OE fabrics, although yarnwicking rate is greater in OE yarns. Absorption rateincreases with increase in pile density but is notaffected by pile ratio.

Maximum absorption for OE fabrics is better thanfor ring fabrics at lower fabric density and forcomparable fabric weight. Maximum absorption hasexcellent correlation (0.942) with the product of fabricweight and pile ratio.

PILE DENSITY

310

Fig. 9-Dependence of abrasion resistance on pile variables [Pile-ground ratio: (e-e-e) 5.0; (0-0-0) 4.5; and (0-0-0) 4.0]

PILE DENSITY

94

Ring fabrics have better dry and wet abrasionresistances than OE fabrics. The abrasion resistance ofthe fabrics is maximum for moderate pile density andhigh pile ratio. The wet abrasion resistance issignificantly lower than dry abrasion resistance of thefabrics.

References1 Lord P R, Text Res J, 44 (1974) 516.2 Larose P, Am Dyestuff Reptr, 31 (1942) 105, 123.3 Holland V B, Am Dyestuff Reptr, 32 (1943) 167.4 Kettering 1 H, Am Dyestuff Reptr, 37 (1948) 73.5 Dhairya Prakash, M. Tech. thesis, Indian Institute of

Technology, New Delhi, 1970.6 lackson E C & Roper E R, Am Dyestuff Reptr, 38 (1949) 397.7 Buras E M, Goldthwait C F & Kraemer R M, Text Res J, 20

(1950) 239.8 Clulow E E, J Text Inst, 60 (1969) 14.9 Cary R T, Text Res J, 49 (1979) 691.

10 DeGruy I, Text Res J, 32 (1962) 873.