7.3.2h.hasani_2

7/29/2019 7.3.2H.Hasani_2

http://slidepdf.com/reader/full/732hhasani2 1/8

Journal of Engineered Fibers and Fabrics 8 http://www.jeffjournal.org

Volume 7, Issue 3 – 2012

Bagging Behavior of Different Fabric Structures KnittedFrom Blended Yarns Using Image Processing

Hossein Hasani, Sanaz Hassan Zadeh, Sanaz Behtaj

Isfahan University of Technology, Isfahan IRAN

Correspondence to:Hossein Hasani email: [email protected]

ABSTRACT This work focuses on the effect of blend ratios andfabric structure on the residual bagging height of knitted fabrics produced from blended rotor yarnsusing image analysis technique. Simplex latticedesign was used to determine the combinations of mixture ratios of the fiber types. Knitted fabrics withthree different structures were produced from

Viscose/polyester blended rotor yarns. Mixture- process crossed regression models with two mixturecomponents and one process variable (tightnessfactor) were built to predict the residual baggingheight.

Keywords: Blended yarns, knitted fabric, residual bagging height, tightness factor.

INTRODUCTION

Fiber blending is commonly defined as the process of forming a mixture of fibers by combing differentfiber components. Blended yarns from natural andman-made fibers have the particular advantage of successfully combining good properties that cannot

be found in only one type of fiber. Viscose/polyester blended yarn is commonly produced in the textileindustry due to several advantages such as less

pilling, less static electrification, easier spinning and better yarn evenness [1].

Bagging is defined as a three-dimensional residualdeformation, seen in used garments, which causesdeterioration in the appearance of the garment. The

places it is seen during wear are elbows, knees, pockets, hips, and heels [2]. Bagging results from thelack of dimensional stability or recovery when

repeated or prolonged pressure is exerted on a fabric[2]. The bagging performance of knitted fabrics isdescribed in different ways for different applications.For applications where the subjective view of theconsumer (knitted garment appearance) is of primaryimportance, the rated performance measure is themost appropriate. For those applications where theobjective of mechanical performance is of primaryinterest (for example, medical textiles such as

compression wear), a measure such as residual bagging is more informative.

In order to evaluate bagging behavior, severalmethods for determining woven and knitted fabric

bagging behavior have been developed [3, 4, 5, 6, 7,8]. Most publications focus on measuring residual

bagging height and related fabric mechanical properties. Yokura et al. [5] measured the mechanical properties of the fabrics using the KES-FB system to predict the bagging volume of the woven fabricsfrom the measured fabric properties. Zhang et al. [6-10] also measured the bagging height of woven fabric

by an Instron tensile tester. Fabric samples wereimposed in five load cycles, and residual baggingheight, bagging resistance, and bagging fatigue weremeasured. They used a regression analysis to predictthe bagging height of woven fabric as a function of

bagging resistance and bagging fatigue. Due tostructural differences, the mechanical response of knitted fabrics is very different from that of wovenfabrics. Thus the bagging behavior of knitted fabricsis different from woven fabrics. Uçar et. al [11]discussed the relationships between residual baggingheight obtained from the fabric bagging test and themechanical characterization determined from theKES-FB system. They predicted residual baggingheight for knitted fabrics by using the standard KES-FB test and without performing fabric baggingfatigue tests. Yeung and Zhang [8] developed amethod to evaluate garment bagging by image

processing with different modeling techniques.

This work focuses on the effect of blend ratios and

fabric structure on the residual bagging height of knitted fabrics produced from viscose/polyester

blended rotor yarns using image analysis technique.A simplex lattice design was used to determine thecombinations of mixture ratios of the fiber types.

EXPERIMENTALViscose and polyester fibers were blended and spunon a short-staple rotor spinning system. The fibers

7/29/2019 7.3.2H.Hasani_2




were processed on these systems using standard mill procedures, adjustments and practices. Viscoseslivers were blended with polyester slivers on thefirst drawing frame and blended slivers were passedthrough the second drawing frame.

The viscose/polyester blended slivers were used to produce a 30-Ne yarn on a rotor spinning machine atstandard atmospheric conditions. The specificationsof the yarn produced are shows in Table I . Using adouble jersey, mini-jacquard, circular knittingmachine (Mayer & Cie, E20, 30”) which wasequipped with positive feeding mechanism, threeinterlock knit structures were created: plain interlock,

interlock cross tuck (which is composed from tuck and loop stitch) and interlock cross miss (which iscomposed from miss and loop stitch on a circular knitting machine). Each of the knitted fabricscontains different fiber blend ratios and differentfabric designs so we can investigate the effect of fabric design and material (fiber type). Loopdiagrams of each sample can be seen in Figure 1.Samples were conditioned for 24 hours in a standardatmosphere. Wale and course count per 100 cm of fabric was measured and then converted to wale andcourse count per cm. The stitch length of the knittedfabrics was measured to determine the unit stitchlength.

TABLE I. Yarn specifications produced from different blend ratios.

FIGURE 1. Loop diagram of knitted fabrics.

To prepare the wet relaxation samples, the fabricswere washed in a domestic washer at 40°C for 30minutes with commercial detergent and tumble driedat 70°C for 15 minutes in a dryer after they had beendry relaxed. This procedure was repeated three times.The samples were conditioned for 24 hours in a

standard atmosphere.

A simplex lattice design with seven replications ateach design point was constructed to determine thecombinations of mixture ratios of two fiber types. Inthis study, a {2, 4} simplex lattice design was used todetermine viscose/polyester blends. Design points

(blend ratios) used in this study are shown in Table I .Before measurements were taken, the stitch lengthfrom an average of ten measurements from eachsample was used in the following equation to obtainthe tightness factor (T.F) of double jersey knittedfabrics:

(1)

Where Lc = Stitch length in a structural cell(structural repeat), and Nc = number of active needlesin a structural cell.

Weights were obtained from an average of threemeasurements of each sample using the balance, andare reported in g/m2. Fabric weights, knit densitiesand the calculated tightness factor of each sample areshown in Table II . The difference between tightnessfactors of each knit structure produced from different

blend ratios is not statistically significant. Thus theaverage of these values was calculated for each fabricstructure and reported in Table III .

c

c

l

N TexF T

..

7/29/2019 7.3.2H.Hasani_2




TABLE II. Properties of knitted fabrics.

Zhang [13] used 12 mm as the predetermined bagging height for woven fabrics. Because knittedfabric is subjected to much higher deformationsduring use, a predetermined bagging height of 21 mmwas used. The relative residual bagging height (Bresidual) at the end of the last cycle, after a recoverytime of 2 minutes, was modeled by Zhang et al. [6, 9]with the following equation:

B residual = (Hnrb/H b) ×100 (2)

Where B residual is the residual bagging height (%),Hnrb is the non-recovered bagging height (mm), andH b, is the predetermined bagging height (mm).

Tensile and shear tests were carried out on auniversal tensile testing machine according toconditions reported by Pan [14]. Because anisotropyis an important point in knitted fabrics, tensile andshear tests were measured in wale and coursedirection and the average of the values were reported.Drape tests of knitted fabrics were carried out using adrape meter.

To analyze the effect of the fabric structure, the

shear, tensile and drape properties of knitted fabricswere measured. The average of values obtained fromdifferent blend ratios was calculated for each fabricstructure. Table III shows the results of thementioned tests.

TABLE III. Results of tensile, shear and drape tests.

1: Work of tensile; 2: Tensile resiliency; 3: Shear stiffness; 4:Shear hysteresis

The procedure of evaluating fabric bagging includescapturing digitized images of bagged fabrics, image

processing of the captured images, selecting criteriato describe bagging appearance, and recognizing

bagging magnitude from these criteria. A group of fifteen knitted fabrics was tested using a bagging testmethod developed earlier [9]. At a predeterminedtime after the fabrics are bagged, they are

photographed with a CCD camera and saved asdigital files. In the photo-taking process, all theimages are transferred into intensity images. Theintensity of an image refers to a two-dimensionallight intensity function, denoted by f(x, y). For the

images, the intensity value at coordinates (x, y) or thegray level at that point lies in the range of (0, 255), 0for black and 255 for white. Technical parameters,such as the magnifying power, position, brightness,and angle of the light source, are kept the same. Thecaptured images were analyzed using Matlabsoftware. This analysis results in a simulated baggingcurve. Figure 2 shows a bagged fabric and simulated

7/29/2019 7.3.2H.Hasani_2




bagging curve achieved by image analysis. The non-recovered bagging height of fabrics was calculatedfrom these curves at the peak points. The residual

bagging height of seven samples was calculated

according to Eq. (1) and the average of themeasurements was reported. Residual bagging heightof knitted fabrics measured using an image

processing technique is shown in Table IV .

FIGURE 2. The bagged fabrics with different structures (a)Half cardigan interlock; (b)Half milano interlock; (c)Plain interlock; and (d) a sampleof simulated bagging curve.

7/29/2019 7.3.2H.Hasani_2




TABLE IV. Residual bagging height of knitted fabrics with different structures and blend ratios.

RESULTS AND DISCUSSION

The Effect of Blend Ratio on the Residual Bagging

Height of Knitted FabricThe findings show that an increase in viscose

percentage will increase the residual bagging heightof fabrics. This phenomenon is observed in differentfabric structures. Figure 3 shows the residual bagging

height related to viscose percentage of yarns for different fabric structures.

The two main causes of fabric bagging behavior arethe stress relaxation of the fibers, owing to the fiber’sviscoelastic behavior, and the friction between fibersand yarns, owing to the frictional restraints in thefabric structure. Fiber–yarn mechanical propertiesand fabric structural properties, such as fabricthickness, weight, tightness factor and interlacing

points, are the important factors influencing the bagging behavior of a fabric [15]. The findings showthat as the percentage of viscose fibers in the mixtureincreases, fabric residual bagging height increases.For polyester fibers, elasticity ratio is high andviscoelasticity ratio is low. In contract, for viscosefibers, elasticity ratio is low and viscoelasticity ratiois high. In addition, the relaxation time for polyester fibers is higher than viscose fibers [13].

The best-fitting regression model that defines therelationship between independent variables (blendratios and fabric tightness factor) and responsevariable (residual bagging height) are selected and

estimated using Design Expert software. The baggingof viscose/polyester knitted fabrics can be predictedfor different blending ratios and fabric tightnessfactors using the following equation:

B residual (%) = 69.5 – 5.56 P + 0.31 T.F + 9.32 T.F 2 (1)

In this equation, “P” is the polyester content of blended yarn and T.F is the tightness factor of knittedfabric, respectively. Figure 4 illustrates regressioncurves fitted to experimental observations. Thecorrelation coefficient between predicted baggingfatigue percentage and observed residual baggingheight is 0.999, indicating a strong predictivecapability of the regression model built. TheANOVA table for the regression model and itsestimated coefficients are shown in Table V . TheModel F-value implies that the model is statisticallysignificant.

7/29/2019 7.3.2H.Hasani_2




FIGURE 3. Relationship of residual bagging height and viscose percentage of yarns for different fabric structures.

TABLE V. ANOVA Table for the regression model and its estimated coefficients.

FIGURE 4. Regression line between predicted and actual bagging fatigue percentage.

7/29/2019 7.3.2H.Hasani_2




The Effect of Knitted Fabric Structure on the

Residual Bagging HeightThe finding reveals that the bagging fatigue

percentage of knit structures changes in the followingorder:

Interlock < Half cardigan interlock < Half milanointerlock

This observation can be seen in Figure 3, and thesituation can be explained easily by looking at thedrape and shear properties of weft knitted fabrics. Aswe know, bending and shear properties are veryimportant factors to the drape of weft knits. When thefabric rigidity decreases, the drape of the fabricincreases [16]. Bagging force induces internal stressin multiple directions including shearing, tensile and

bending.

Shear stiffness is affected by slipperiness at loop

intersection, elastic deformation and bendingdeformation of the yarns, while shear hysteresis isinfluenced by the coefficient of friction and contactlength and knit density [17].

Table III shows that half milano interlock representsthe higher shear properties and drape coefficientcompared with other structures. Thus, this structurerepresents higher resistance to slippage betweenyarns or loop and fiber contact in the intersections.

As shown in the stitch diagrams (Figure 1) the yam paths for half milano interlock fabrics are complex

compared to the plain knit fabrics. There are manylong contact areas and complex linkages between thestitches. Most linkages cross each other at everysuccessive course, so this structure makes the fabricmore rigid against deformation. Also, fabrics withmore intricate and longer linkages between stitcheswill tend to recover less deformation due to morefrictional resistance, thus increasing residual baggingheight. Therefore, there is a positive relationship

between fabric rigidity parameters and residual bagging height. Increased fabric rigidity increasesresidual bagging height.

On the other hand, tensile properties such as WT andRT of plain interlock are higher than other structures.Higher RT means that the structure has higher resiliency while removing the tensile force. Thisincreases fabric recovery after deformation due to itsspring-like behavior, which leads to a decrease inresidual bagging height. Thus plain interlock fabricrepresents the lowest bagging height.

Also, the structures produced from miss stitchesrepresent the higher residual bagging height thanthose produced from tuck stitches. It can be due tothis fact that the structures produce a fabric withmore rigidity as well as more frictional resistancewhich results in less deformation, thus increasingresidual bagging height. Knitted fabric with plaininterlock structure produced from 100% polyester yarn has the lowest residual bagging height.

CONCLUSIONSResidual bagging height of viscose-polyester knittedfabrics was modeled through a regression model inwhich blend ratios and fabric structure are predictor variables. The model has high prediction capabilityindicated by a high, positive correlation between

predicted residual bagging height values andobserved bagging height values. As the percentage of viscose fiber in the mixture increases, residual

bagging height increases. It can be due to higher

viscoelastic modulus and smaller relation time of theviscose fibers. Also, the finding reveals that theresidual bagging height of fabrics is lower in thestructures which are produced from miss stitches.Knitted fabric with plain interlock structure producedfrom 100% polyester yarn has the lowest residual

bagging height.

REFERENCES

[1] Baykal P. D.; Babaarslan O.; Rizvan E.;FIBRES & TEXTILES in Eastern Europe,2007, 15(4), 21-25.

[2] Amirbayat J.; International Journal of

Clothing Science and Technology, 2005,16(5), 308-313.

[3] Jaouachi B.; Louati H. and Hellali H.; AUTEX

Research Journal; 2010, 10(4), 110-115.[4] JUODSNUKYTĖ D.; GUTAUSKAS M.;

ČEPONONIENĖ E.; MATERIALS

SCIENCE; 2006, 12(3), 243-246.[5] Özdil N.; FIBRES & TEXTILES in Eastern

Europe; 2008, 1 (66), 63-67.[6] Zhang X.; Li Y.; Yeung K. W. and Yao M.;

Textile Research Journal; 1998, 67, 5191-518.

[7] Zhang X.; Li Y.; Yeung K. W. and Yao M.;

Textile Research Journal; 1999, 68, 599-606.[8] Yeung K. W.; Li Y. and Zhang X.; Textile

Research Journal, 2002, 72(8), 693-700.[9] Zhang X.; Li Y.; Yeung K. W. and Yao M.;

Textile Asia, 1999, 30 (6), 33–36.[10] Zhang X.; Li Y.; Yeung K. W.; Textile

Research Journal, 2000, 70(9), 751–757.

7/29/2019 7.3.2H.Hasani_2




[11] Ucar N.; Realff M.; Radhakrishnaiah P. andUcar M.; Textile Research Journal, 2002,72(11), 977–982.

[12] Chot M.; Ashdown S. P.; Textile Research

Journal, 2000, 17(12), 1033-1045.[13] Sengöz N. G.; Textile Progress; 2004, 36, 1, 1-

64.[14] Pan N.; Zeronian S.; Ryu H.; Textile Research

Journal, 1993, 63(1), 33–43.[15] Kirk W.; and Ibrahim S. M.; Textile Research

Journal 1966, 36, 37-47.[16] Amirbayat J.; Hearte J. W. S.; Journal of

Textile Institute; 1989, 80(1), 51-70.[17] Choi M.; Ashdown S., Textile Research

Journal; 2000, 70(12), 1033-1045.

AUTHORS’ ADDRESSES

Hossein Hasani

Sanaz Hassan Zadeh

Sanaz Behtaj

Isfahan University of TechnologyIsfahan 84156IRAN

7.3.2h.hasani_2

Documents