Assessment of Crease Recovery Values of Textile Fabrics by Different Instruments

Indian Journal of Textile Research Vol. 8, March 1983, pp. 16-22

S SUBRAMANIAN, G R PHALGUMANI & B R MANJUNATHA Textiles Committee, Bombay 400018 &

M S SITARAM, A W SHRINGARPURE & I G BHATT Cotton Technological Research Laboratory, Bombay 400019

Received 16 January 1982; accepted 26 October 1982

( A comparative evaluation of the crease recovery angles of textile fabrics measured using three different crease recovery testers, viz. Monsanto, Metrimpex and Shirley, has been made to assess the recovery characteristics of textile fabrics in the true sense. The effect of different factors like load, loading/relaxation period, sample size. crease length and spacer (particularly used in the Monsanto method) on the crease recovery values has also been studied. It has been observed that the evaluation of commercial samples cannot be made by the Monsanto method, as the measured angles in this case do not represent the true values. However, both the Metrimpex and Shirley testers do furnish equivalent values according to the basic physical pl"inciple of property measurement, Metrimpex tester could be used preferably, provided certain precautions are taken, as it enables measurements for more than one specimen at a time, as against the Shirley tester which can handle only one specimen. It is recommended that the standard method of determination of crease recovery values of textile fabrics should involve the formation of crease/wrinkle as per the basic physical principle without any spacer to measure the recovery values in the true sense. ') /'I With the advent of resin finished cotton fabrics and procedures adopted differ with regard to sample size, their blends in the consumer market, objective load and loading period, relaxation period, mode of assessment of the recovery angles of a finished fabric application of load on the sample and insertion of has assumed considerable imrqrtance. Several spacer in between the two folds of the specimen. These methods have been deyeloped for measuring and procedural differences are briet1y enumerated in Table assessing the recovery characteristics of such finished 1 to show their relevance to the recovery data of these fabrics 1 .7. While the evaluation of fabric recovery instruments. In the present investigation, a compara• behaviour using photographic standards has not been tive evaluation of the crease recovery angles of textile favoured due to its subjective nature, new instruments fabrics by three crease recovery testers, viz. Monsanto, are finding their way into the market for measuring the Shirley and Metrimpex. has been made to assess the recovery angles objectively. Among the different recovery characteristics of textile fabrics in the true instruments, Tootal recovery tester was the earliest, sense. This would help in arriving at a uniform while Monsanto wrinkle recovery tester and Shirley standard method for testing the crease recovery of crease recovery tester, which were developed later, are textile fabrics. now in general use. A recent addition of interest to the Materials and Methods crease recovery testers is the Metrimpex crease Fabric samples of cotton, woollen and man-made recovery tester developed in Hungary. These fabrics and blends with varying constructions were instruments are based on the principle of deliberately used for evaluation of recovery angles. The creating a fold in the specimen in question, under a constructional parameters of the fabrics are given in given load and period and then allowing the material Table 2. to recover for a given time period. The angle so formed In the case of four cotton fabrics, viz. drill, sheeting, between the two leaves of the folded fabric strip is poplin and cambric, durable press (OP) characteristics measured with the help of a protractor. This procedure were imparted by treating them with dimethylol is repeated in both warp and weft directions and is dihydroxyethylene urea (OMOHEU) as the crosslink• applied to the material even in wet condition. ing agent. Even though the basic principle of the measurement The fabrics were evaluated for crease recovery of recovery angles is same in all these instruments, the angles using the following instruments as per the

I ~ r I 'II II IJI min 67.1 C " SUBRAMANIANperiodw.e--3Us5070495859Warp64.8530.15925864.4533.4s33.153Us32.5s33.4596.4530.9s34.452Us37.9534.6554.2510333.2s13.5532.3532.8s99.3513.9535.4531.6s31.0532.5s34.0513672.5s32.45905832.0s32.2s22.4s795831.4558.25948116.4517.6513.8s17.5518.0513.6sLoading246.2241.088Weft246.659174.072114.8103.7128.4116.2118.4199.6166.9109.4127.959.9124.8114.319.5195.8109501074713811679.670.652.9100.0P6870898658909058928084728858Count8651109.9865'5CompositionIlOO.OCRelaxationReferencelOO.OC%lOO.OC8lOO.OC100.04 5periodlOO.OCmin59I520.049.711.719.1 19.0P17.219.6S4.8W10192000Load (CC)Wt/m2500el600X-CodeX-22X-15X-20X-'IlX-14X-25X-24X-21X-16X-23X-17X-18X-19X-Y-I PThreads/inCSamplet C01.:20.02$.4g,...15.0 79256 3 , ASSESSMENT x 40.050.830.0 size--(2F) OF CREASE45.2g P RECOVERY VALUES OF TEXTILE FABRICS sheetingTerrycotsheetingsuitingsheetingCottonTerrycotWoollensheetingvoilecontrolsheeting Y-II No. Cambric 40.150.313.913.413.314.114.216.3 VC sheetingCotton sheetingShirleyMetrimpex Monsanto·(widthCottonWarp x length) mm 65.967.566.264.275.0TerrycotPolyesterCottonPoplinCambricDrill C & __ •••.T~ '/A 17 82.8 C Terrycot*Spacer of thickness 0.16 ±0.01 mm. InstrumentSample ,:.r C, Cotton; P, polyester; V, viscose; W, wool. ~AL .~ Table 2-Constructional Parameters offf~ Samples,,..--- Used for CRA ..... Measurement<.A Table I-Standard Specifications for Different Recovery Testers INDIAN J TEXT RES, VOL. 8, MARCH 1983 recommended standard procedures: protractor inside the above housing. The instrument (1) Monsanto wrinkle recovery tester. has a time indicating device, meant for registering the (2) Shirley crease recovery tester. unloading period and for measuring the crease (3) Metrimpex crease recovery tester. recovery angle (i.e. relaxation period of the specimen). A brief description of the instruments is given below. During this period, a second specimen holder carrying five specimens can be placed below the pressure plate Monsanto Crease Recovery Tester and compressed. Thus, 10 specimens can be handled A disc and a protractor are mounted coaxially on a simultaneously. vertical support, so that they are free to rotate about a The fabrics were evaluated for both dry and wet horizontal axis. The centre of the disc-protractor crease recovery angles. assembly is marked and a vertical guideline is drawn on the support from the centre mark to the base. The Results and Discussion disc is provided with the vernier, having a central zero The recovery angles of textile fabrics measured by point, which indicates on the protractor the angle the three instruments-Monsanto, Shirley and formed by the creased specimen, when it is mounted in Metrimpex-are projected in Figs. I and 2. It is tireclamp. The apparatus also has a provision intended' 300 7, to compensate for fabric thickness. A clamp IS o MONSANTO attached to the face of the disc to support the specimen ~Imi METRIMPEX holder. The important accessories include specimen holder and transparent plastic press. • SHIRLEY Specimen holder-This consists of two super• 200 imposed 16 mm wide metal leaves of different lengths fastened together at one end. The distance between the '" •• free ends of the two leaves is 23 mm. The thickness of .., the top shorter leaf/spacer is 0.16 ± 0.01 mm. There is a « rr: line drawn on the top leaf parallel to and exactly 18mm '-' 100 from its free end. Transparentplastic press-This consists of two superimposed le.avesof equal length (approx. 95 mm) and width (about 20 mm) fastened together at one end. A platform of the same plastic, approx. 23 mm long and o POLYIiSTER OflILL POPLIN CAMBRIC as wide as the press leaves, is permanently attached to VOilE the outer surface of the free end of one leaf, with the Fig. I-Crease recovery angles of textile fabrics by different outer edges of the leaf and platform flush. instruments

Shirley Crease Recovery Tester O MONSANTO r.::x:::s&ilill METRIMPEX • SHIRLE.Y This apparatus consists of a circular dial, which 300 carries the grips for holding the specimen. Directly under the centre of the dial are a knife-edge and an index line for measuring the recovery angle. The scale of the instrument is engraved on the dial. The important accessory is the loading device which 200 consists of a press to apply the required load (2 kg) on an area of 25.4 x 25.4 mm of the folded specimen '" ..,• placed between the two flat press/glass plates . .0( a: '-' Metrimpex Crease Recovery Tester 100 This apparatus consists of a vertically positioned specimen holder, which can carry five specimens. A pressure plate, the movement of which is controll~d by a loading and unloading mechanism, is used for o compressing all the five folded specimens held by the SHEETING DRILL CAMBRIC specimen holder. The protractor is placed in a transparent protective housing. The specimen holder, Fig. 2-Crease recovery angles of durable press treated fabrics by after unloading, is kept in a postion above the differen t instruments

\ t1' SUBRAMANIAN el al.: ASSESSMENT OF CREASE RECOVERY VALUES OF TEXTILE FABRICS

interesting to observe the conspicuous outcome of the Effect of Procedural Differences of Instruments on eRA Values results in the case of untreated controls and DP-treated It has already been mentioned that the operation of cotton fabrics of medium, coarse and fine varieties. these instruments varies in sample size, load and The recovery angle values are highest for Monsanto loading period and relaxation period (Table 1) in the tester and lowest for Shirley tester, irrespective of measurement of CRA values of textiles. Therefore. the fabric type or treatment. This trend remains same even effect of these factors has been studied in detail. in the wet condition (Table 3). The results also reflect Ejjec,t of load and loading period on eRA z'alues• consistency in this tre.nd. Further, the recovery The effect of load and loading period on the CRA behaviour offabrics of different weaving constructions values has been studied for each of the three also shows varying CRA values of similar trend, instruments, keeping the loading and relaxation compatible within each method. Thus, the plain weave periods constant in all the studies. The results of sheeting, poplin and cambric shows nearly uniform presented in Fig. 3 indicate that the load and loading values, while the drill weave of coarse fabric gives period have great influence on the CRA values. The considerably different values within each instrument, shorter the loading period, the greater is the CRA as expected. Table 4 illustrates this aspect well. value, irrespective of the load. At the same time, the To investigate the possible causes for this type of load also plays an important role with respect to discrepancy in results, an in-depth analysis of the loading period; the higher the load and loading period, various factors governing the procedures in the the smaller is the recovery value, as expected. operation of these instruments has been carried out. It is also reiterated that for the same sample, Monsanto recovery values are invariably higher than Table 3-Wet eRA Values Using Different Instruments the others, irrespective of the load or loading period. Further, it is clear from the Metrimpex and Shirley recovery data (Fig. 3) that the crease recovery values 271263255278270249157144152160145198131239240125126238Metrimpex136130183252259253Shirley X-X-II 975 MonsantoCRA values P + T SheetingPoplinCambricDrill controlDP control DP DPcontrol DP Sample description and code No. measured with 500 g load for 5 min are comparable P,Sheeting Warp; T, control Weft. with those me

185 D 1 MINUTE M - MONSANTO ~ 5 MINUTES ME-METRIMPEX

• 10 MINUTES S - SHIRLEY

170

X-5 1019317869661929682178769188104192101881898590167177156 8771137 87F-2F-I91 controlCambric X-II F-I, specimen folded face to face. F-2,P, Warp; specimen T, Weft. folded back to back. ~I!; it' "Ol~~~ !~. ~ M ME 5I M ME ;~~~~ 5 M ME S ~g~g~g~g~g~g~g~gW~ Fig. 3-Effect of load and loading period on CRA values of cotton sheeting (code No. X-7)

19 INDIAN J TEXT RES, VOL. 8, MARCH 1983

In this connection, it is pertinent to mention the work by Shirley method. The results (Table 7) point out that of Skelton 11 , wherein the crease recovery tests were while confirming the definite effect of the spacer on carried out with and without spacers of four different CRA values, measured in the l50-280c range, it is thicknesses in the creasing press while carrying out the evident that such an influence is ineffective on CRA theoretical and experimental investigations of the values lower than 1500 and higher than 280-30OC. It is, crease recovery of plain weave fabrics woven from however, interesting to observe that the insertion of stpple yarns. The thicker the spacer, the greater was the spacer in between the specimen, while creating a CRA value of thermovyl fabric (Table 6). crease/fold, has yielded values comparable to The study of Markezich et al. 12 using vertical strip Monsanto values in the wash and wear range. A Monsanto tester has brought out some of the sources similar comparison reveals an identical trend in crease of error in the wrinkle recovery tester and test method, recovery values obtained using Monsanto and as the agreement of the data was not found good Metrimpex instruments with and without the spacer among the laboratories. The corresponding AA TCC (Table 8). Thus, the effect of metal spacer in the test method 1 also shows such significant differences in Monsanto tester is the main reason for the highest laboratory precision. It is rather intriguing that they values of CRA among all the three instruments. have not considered the importance of the basic Consequently, it derives from the present data that principle of fold/crease formation without the for proper evaluation of recovery angles, a realistic influence of any outside agency, like the introduction formation of crease is essential at the time of fabric of spacer, while working on the various other sources 260258231222257249172231220225225spacer203223209211242324331304307314147194151121142189141161215199240234129178134147183120170120154189188125147321With192CreaseMonsantot recoveryCodeX-X-25X-22X-24X-23X-IIy-X-15X-16X-19X-20X-21X-14 9632I angles of error contributing to the problems of obtaining Table 7-Effect of Spacer--4.. on the Crease Recovery Values of sheeting CambricDrillvoile No. SheetingBlendedsheetingsheeting fabricsColton fabrics spacer WoollenTerrycotSheetingPolyestertLoad.Man-made 500 fabrics fabrics g:Shirley* loading periodDifferent 5 min: Fabrics and relaxation period, 5 min. inter-laboratory agreement on the recoverySample data. Terrycot ---- '--""~-'-'~'-- Without *Load. 2000 g: loading period.-- I min; and relaxation period, I min. To find out the effect of spacer on the full range of recovery angles, different fabric types, viz. cotton, man-made, blends and woollen, were measured for their recovery values with and without spacer of 0.20 mm thickness, similar to that used in Monsanto tester

Table 5- Effect of Sample Length (SL) and Crease Length (CL) on CRA Values [Sample, terrycot sheeting X-18]

Size of specimenSize50.8(SL of x specimenxCL)P+T 31.819125.4195 12.719219.1196189 6.4CRAP+T191195190193CRA mm 38.144.550.831.8(SLmm x x 25.4 CL) 25.4 x 25.4

Note: In all the cases, pressure is kept constant at 1100 gin' (i.e. 1.7 gjmm'). p, Warp: T. Weft.

Table 6- Effect of Spacer Thickness on CRA Values of Thermovyl Fabrics *

Spacer CRA thickness deg ellI

0.550 149.5 0.234 142.3 0.163 138.1 0.094 126.5 Routine test 96.5 without the spacer *Data from ref. II.

II I If IHI I,illj'l 11'lill' ''11111111'1 J I 1111111"'01111i"I~1 II 111I1 II' III' I~ SUBRAMANIAN el at.: ASSESSMENT OF CREASE RECOVERY VALUES OF TEXTILE FABRICS resist deformation, and at the same time regain its 265269194290165144196253143136-314181191 X-l1X-25- 157145-- Table 8-ComparisonWOs183295160298289188317252Monsanto296325272281235227201 322190200165190195 286Metrimpex294298 (X-II(X-7CodeX-X-17X-21 ofDP) 9DP)7 CRA Values278262190 of Monsanto and original configuration existing prior to deformation. sheetingSheetingDrillCambricTerrycotsheetingSheeting wetcontrol wetdry drywet DPcontrol WS,WoollenTerrycot with spacer; WOS, withoutws spacer. Given the same ability of the material to recover from Polyester No. MetrimpexTesters Sample the deformation, one should standardize the extent of deformation which the material is made to suffer, before any attempt is made to measure- the recove~y characteristics. In all the three methods, the baSIC mechanism involved is to form .a sharp crease or wrinkle under a given load and period and thereafter allow the material to recover from the induced deformation for a given period. One has to positively make sure that the deformation (in the present case a crease) has been made in the same manner in all the three cases, before comparing the results obtained from these methods. The basic mechanism in creasing of the fabric is one of fibre bending, involving the flow characteristics of the polymer. Introduction of the metal sheet (spacer) between the leaves of the fabric, while it is being deformed, has already been found to . cause considerable difference in the observations. This has been proved using strips of tracing paper creased under identical conditions with and without the spacer and examining them under a low power microscope. The resultant micrograph is shown in Fig. 4.. bending/folding/creasing in the procedure of measurement with each of the instruments. Further examination of the sample holder from the viewpoint of loading mechanism also affirms that apparently no uniform pressure is exerted on the specimen during the formation of crease. This is also attributed to the presence of the metallic spac~r inserted between the folds of the specimen, which is fixed in the plastic holder at one end of which 500 g load is kept. As mentioned in the AATCC test method, this plastic press has a tendency to warp in usage, resulting in non-uniform distribution of load on the specimen, affecting the results thereby. The convenience of minimum sample handling has actually contributed to the higher recovery values at the expense of the basic principle of crease/bend formation. Thus, these methods cannot be compared with each other. Coupled with the multiple bends resulting from the introduction of metallic spacer, the observed crease recovery angle can be as high as 25-40c in the critical range 200-280°. The load and period of deformation and the recovery period, all need to be standardized, before the crease recovery angles as obtained from these two methods could be compared.

Mechanism of Bending It appears that the mode of crease/fold formation plays an important role in determining the realistic CRA. The recovery of a textile fibre is dependent upon its structural characteristics, particularly the secon- dary bondings. To be resilient, the fibre should not Fig. 4-A view of the lateral edge-on section in the micrograph

21 INDIAN J TEXT RES, VOL. 8, MARCH 1983

1t is observed that the insertion of metal strip/spacer causes two right angle bends in the material instead of a sharp single crease. Ihe recovery of the material at each of the right angle bends causes the overall angle between the two leaves of the strip to increase (, considerably. This in effect would mean that in Monsanto tester, one measures the consolidated angle of two bends as against a single bend or fold which is

desired to be created under the method. In many cases, WITHOUT STRIP/SPACER WI1'H STRIP/SPACER instead of multiple bends just a curvilinear bend may Fig. 5-- Effect of spacer on crease be formed, showing a single illusory angle (Fig. 5) whose recovery characteristics are far greater, thus leading to erroneous conclusions. However, the Table 9~Cornparison of CRA Values of Shirley and Metrirnpex Testers measured recovery angles are not affected above the DP range where there is high recovery, and below the Sample Shirley Metrimpexvalues,P+27429629825626626015l26716J184172DPDPControltheMean ten values of allT angles of 1500 where there is no significant recovery. description------~-- values,P+T ~~-~-~~~~-~ControlMean of five valuesafterdeletingfive155 end values Thus, it is clear that the sample bending mechanism in and code156155170 No. the Monsanto tester is far from what it claims to be. ControlDP The measurement of the recovery of multiple folds/bends/wrinkles/creases is yet an unexplored field requiring deeper study. Hitherto, workers 10.13 have attempted to modify the Hungarian and Iootal Sheeting 148 261 methods to bring them at par with Monsanto method X-7 on the mistaken assumption that the latter is a Drill 153 246 X-9 standard method. Thus, we find introduction of Poplin 142 268 spacers and increasing of the test specimen size to X-5 boost up the measured eRA. A notable attempt is that Cambric 162 286 of Doshi and Dixit 10 who have suggested a modified X-IJ Hungarian method to simulate the Monsanto values. P, Warp; T, Weft. Although the Monsanto method is highly attractIve to textile fabrics should involve the formation of persons engaged in resin finishing of tex~iles d~e to the high CRA values recorded by this techmque, It should crease/wrinkle as per the basic physical principle be clearly understood that the Monsanto instrum.ent without any spacer to measure the recovery values in fails to meet the requirement when the physical the true sense. principles of fold formation are examined critically. References Assessment of eRA Values of Shirley and Metrimpex I AATCC test method: 66-1978, AATCC technical manual, 54 Testers (1978) 286. 2 ArchibaldL B,BailieJ, EwingW H & Spencer-SmithJ L, J Text The CRA values obtained by Metrimpex and Inst, 55 (1964) T 477. Shirley testers compare well with each other (Table 9), the former scoring a plus, provided certain precautions 3 BostwickC, Am Dyestuff Reptr, 51 (1962) 386. 4 Determination of the recorery;rom creasing of textile fabrics by are taken. In Shirley tester, only one specimen can be measuring the angle of recovery, Britishstandardshandbook assessed at a time, while in Metrimpex tester, five No. II, 1974,4,35. specimens can be assessed at a time. However, it has 5 GeorgeM, MarkezichA R & O'Connor R T, Text Chern Color, 2 been observed that due to the non-planarity of the (1970) 168. sample block after continuous usage, the two end 6 Hebeler H H & Kolb H J, Text Res J, 20 (1950) 650. 7 Lako J & Veer L S, J TeXllnst, 53 (1962) 99. specimens always show higher CRA values than the 8 Shirley institute leslleaflet DF 2A, Jan 1957. centre specimens. It is believed that with usage, the 9 METEFEM-CheckingInstrumentfor Wrinkleundo Type: FF- sample mounting block, made of polyamide material, 07, Melrimpex manual, Budapest. tends to warp, leading to uneven loading along the 10 Doshi S M & Dixit M D, Colourage. 26 (1979) 3. II Skelton J, J Textlnst, 59 (1968) 261. length of the block. The plane of the block should, 12 MarkezichA R, Smith M M, Allen H A & Tallant J D, Texi therefore, be checked often and CRA should be Chern Color, 5 (1973) 85. calibrated against that of Shirley. Hence, the standard 13 ShahJ K, PatelA B,Dave B S& ShroffJ J,Colourage, 23(1976) method of determination of crease recovery values of 30.

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