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Properties of Three-Thread Fleece Fabrics GULAY OZCAN

AND

CEVZA CANDAN

Technical University of Istanbul, Department of Textile Engineering, Istanbul, Turkey ABSTRACT This study investigates the effect of course length and washing processes on the physical characteristics and shrinkage behavior of three-thread fleece fabrics. Three groups of fabrics in five different course length ranges are produced, and their areal density, fabric thickness, pilling, and abrasion resistance are measured in accordance with the relevant ISO and British Standards. The dimensional changes of the samples in both width- and length-wise directions, together with skewness (%), are also measured after washing and tumble-drying cycles. The experimental results are evaluated with the SPSS statistical program.

In the past decades, depending on fashion trends, the production range of knitted goods has been expanded with new fabric designs as well as new fibers and their blends. Although the dimensional behavior of some standard weft knitted structures, such as plain jersey, interlock, two-thread fleece, and double and single pique has been investigated in various combinations [1–24], a literature survey reveals almost no work on the properties of three-thread fleece fabrics. Accordingly, we have conducted a comprehensive study to investigate the fiber and yarn properties as well as laundry conditions on the dimensional behavior of such fabrics. This paper presents the preliminary results of this on-going project, which have been evaluated according to a MANOVA analysis using the SPSS statistical program. We intend to underline the main variables affecting some physical and dimensional properties of three-thread fleece fabrics.

Materials and Method For the work, three groups of fabric samples were knitted on a 90-feed, 28-cut single jersey circular knitting machine, 30” in diameter, using yarns of different fiber compositions. Detailed information about the samples is given in Table I. All samples were then subjected to a relaxation treatment comprising five washing and tumble-drying cycles, similar to the process suggested by the Starfish project [25]. The samples were placed in the washing machine, paying particular attention to loading, the recommended amount of washing powder was added to the dispenser, and the machine was set to wash at 60°C with a long spin (e.g., final spin at 800 rpm for 4 minutes). Upon completion of the wash cycle, the load was tumble-dried at Textile Res. J. 75(2), 129 –133 (2005)

the highest temperature setting until dry. Following the first tumble-dry cycle, the load was returned to the washing machine and, using the rinse-only cycle (including a final spin at 800 rpm for 4 minutes), it was thoroughly re-wetted. Afterwards, the fabrics were tumble-dried for the same length of time as before. The previous step was repeated three more times. After completion of the five cycles, the test specimens were conditioned in a standard atmosphere until they reached equilibrium. After the laundering process, areal density, pilling, bursting strength, and abrasion resistance were measured in accordance with the following standards: areal density—ISO 3801, abrasion resistance–BS 5690, bursting strength—ISO 2960, and ICI pilling—BS 5811. The dimensional changes of the samples in both width- and length-wise directions, together with skewness (%), were also measured after each washing and tumble-drying cycle. Wale and course density were measured as explained in our previous works [7–9, 20, 22]. Mean values of courses/cm and wales/cm were then calculated, and the product of these means was used to determine the stitch densities of the samples. In order to evaluate the resistance of the samples to abrasion, the fabrics were subjected to 20,000 rubs, and for comparison reasons, the percent weight losses of the samples were calculated at the end of each test cycle. The results were treated statistically with the help of multivariate analysis of variance (MANOVA) tables to indicate the significance of the effect of course length range and washing processes on fabric properties. Regression analysis was used to show the significance of the relations (significant at a level ⬍ 0.05 and highly significant at a level ⬍ 0.01). 0040-5175/$15.00

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TEXTILE RESEARCH JOURNAL TABLE I. Details of the samples.

Samples

Course length ranges

First group

1.820–713–290 2.840–730–290 3.850–750–290 4.864–755–290 5.870–765–290 1.765–645–290 2.786–660–290 3.810–680–290 4.815–700–290 5.840–725–290 1.805–670–290 2.825–700–290 3.840–720–290 4.865–735–290 5.880–743–290

Second group

Third group

Results and Discussion FIRST GROUP

OF

FABRICS

Although the MANOVA results indicate that the course length ranges can have a significant effect on areal, course, and stitch density of the fabrics (F ⬎ 25 and Sig. ⬍ 0.001), the polynomial regression analysis does not give an exact relation between CL (course length) and the relevant fabric properties for this group. The results of the linear regression analysis for laundering and tumbledrying for five cycles show that washing has a significant effect on areal, wale, course, and stitch densities as well as fabric bursting strength. Weight per unit area (areal density), wale, course, and stitch densities and bursting strength increase considerably after laundering and tumble drying (Figure 1). The greatest areal, wale, and course densities are obtained for fully relaxed samples. Depending on the number of relaxation processes, the dimensional changes in length %(⫺) (F ⫽ 6.81, Sig. ⫽ 0.001), and width %(⫺) (F ⫽ 15.61, Sig. ⬍ 0.001), together with skewness percentages (F ⫽ 6.81, Sig. ⬍ 0.001), are quite small, though they are statistically significant. SECOND GROUP

OF

Yarn types face yarn: Ne30/1 cotton-polyester (67/33), carded tie-in yarn: Ne30/1 cotton-polyester (67/33), carded fleece yarn: 10/1 cotton, open-end ␣e ⫽ 3.75 (for all yarns) face yarn: Ne30/1 cotton, combed, ␣e ⫽ 3.60 tie-in yarn: 30/1 cotton, carded, ␣e ⫽ 3.75 fleece yarn: 10/1 cotton, carded, ␣e ⫽ 3.75 face yarn: 30/1 cotton, combed, ␣e ⫽ 3.60 tie-in yarn: 30/1 cotton-polyester (50/50), carded, ␣e ⫽ 3.75 fleece yarn: 10/1 cotton, open-end, ␣e ⫽ 3.75

ing strength (F ⫽ 161.57, Sig. ⬍ 0.001). These dimensions increase dramatically after laundering and tumbledrying for five cycles. Figure 3 shows the effect of full relaxation on bursting strength of the second group of fabrics.

FABRICS

The polynomial regression analysis indicates that for this group, the effect of CL range on course density (F ⫽ 38.24, Sig. ⬍ 0.001) of the three-thread fabrics is much more significant than on other fabric properties. An increase in the CL range of the fabrics causes the course density to decrease considerably (see Figure 2). On the other hand, the full relaxation process has a very marked and significant effect on areal (F ⫽ 219.69, Sig. ⬍ 0.001), wale (F ⫽ 172.74, Sig. ⬍ 0.001), and stitch densities (F ⫽ 59.97, Sig. ⬍ 0.001) and on fabric burst-

FIGURE 1. Effect of five washing cycles on areal density and bursting strength of the first group of fabrics

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FIGURE 2. Effect of CL range on course density of the second group of fabrics.

FIGURE 4. Effect of CL range on dimensional stability of the second group of fabrics.

FIGURE 3. Effect of five washing cycles on bursting strength of the second group of fabrics.

The statistical evaluation implies that the CL range has a more significant effect on the dimensional changes of the fabrics compared to each and every cycle of the relaxation process. An increase in course length range causes widthwise shrinkage, but it causes lengthwise extension. The lowest values are obtained for the 815– 700 –290 course length range. Both the number of washing cycles and the CL ranges for this group have only a modest effect on fabric skewness. Figure 4 shows effect of CL range on the dimensional stability of the fabrics. THIRD GROUP

OF

FABRICS

These fabrics behave in the same manner as the second group. Course density decreases with the CL range

(R2 ⫽ %64.0, F ⫽ 26, Sig. ⬍ 0.001) from 15.2 to 12.4 (see Figure 5). There is no significant change in areal, wale, and stitch densities or in bursting strength of the fabrics with the CL level. Full relaxation has a significant effect on areal (F ⫽ 379.91, Sig. ⬍ 0.001), wale (F ⫽ 172.23, Sig. ⬍ 0.001) and stitch densities (F ⫽ 34.01, Sig. ⬍ 0.001) and on fabric bursting strength (F ⫽ 104.53, Sig. ⬍ 0.001) but there is no similar relation for course density. Figure 6 shows the effect of full relaxation on the bursting strength of the third group of fabrics. Our polynomial regression analysis shows that neither increases in the course lengths of the yarns (face and tie-in) nor the progress of the relaxation treatment has a marked effect on the dimensional stability, including the skewness, of the third fabric group.

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TEXTILE RESEARCH JOURNAL ABRASION RESISTANCE

AND

PILLING

A close examination of the abrasion behavior of the fabrics shows that the effect of relaxation is much more significant than the course length ranges selected for the samples, such that for each group, fully relaxed fabric samples have lower weight loss percentages. When the resistance of the fabrics to pilling is graded, it is the second group that shows the highest resistance, followed by the third and first groups. The abrasion resistance and pilling tests of the fabrics are shown in Table II.

Conclusions

FIGURE 5. Effect of CL range on course density of the third group of fabrics.

FIGURE 6. Effect of five washing cycles on bursting strength of the third group of fabrics.

The purpose of this research is to discuss the preliminary results of our on-going project on the dimensional behavior of three-thread fleece fabrics. We have underlined the main variables affecting some physical and dimensional properties of these fabrics. Our results from the first step of the project show that course length range can be a very important production parameter, affecting both the physical and dimensional properties of the fabrics. In general, changes in course length for each group have an effect on the dimensional properties of the relevant fabric samples. However, our results indicate that the course length ranges selected for such work are quite important and should be as wide as possible so that their effect on fabric dimensional properties can be observed much more clearly. The relaxation treatment has a greater influence on both the physical and dimensional properties of the fabrics, when compared to the effect of changes in course lengths for each group. Fabrics made from polyester-cotton yarns have lower pilling rates and higher bursting strength values. Fiber type also seems to have an effect on fabric dimensional properties that is as important as the CL ranges close to each other: samples produced from polyester-cotton yarns tend to have a higher shrinkage potential.

TABLE II. Abrasion resistance and pilling tests results of the fabrics. First group of fabrics

Grey fabrics

Fully relaxed fabrics

Second group of fabrics

Third group of fabrics

CL range

Abrasion weight loss %

Pilling ICI

Abrasion weight loss %

Pilling ICI

Abrasion weight loss %

Pilling ICI

1 2 3 4 5 1 2 3 4 5

2.4 1.6 1.56 3.3 1.8 0.7 1.6 1.1 2.5 1.9

3–4 4 3–4 3 4 3–4 3 4 3–4 3

5.4 10.4 5.4 7.8 4.9 2.4 4.6 4.6 4.7 4.8

4 4 4 4 4 4–5 4–5 4–5 4–5 4

8.3 8.3 7.8 6.25 8.1 1.9 2.2 1.1 2.8 1.9

4.5 3.4 3.4 3.4 4 4 4 4 3.4 3.4

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The information acquired in this research shows that the laundering and tumble-drying processes have a very important effect on the fabrics’ physical and mechanical properties, because the fabrics become more tight and compact after these treatments. On the other hand, observed differences in the effects of the course length ranges on the physical properties of the fabrics can be attributed to different polyester contents of the fabric groups. Our findings thus far show the need for investigating different course lengths, fiber types, yarn counts, and dying processes on three-thread fleece fabric properties. Therefore, we have made a detailed systematic study by controlling knitting variables as well as laundering conditions (temperature, different washing regimes, use of detergent, etc.) in order to investigate the dimensional behavior of three-thread fleece fabrics.

9.

10. 11.

12.

13. 14.

15.

ACKNOWLEDGMENTS We are thankful to Hakan Karakaya and the other plant managers of Bilkont’s Spinning, Dyeing and Knitting Divisions for permission to produce the fabrics used for the work. Special thanks also go to A. Sheikhzadeh and T. Demirciog˘lu for their invaluable time to test the fabrics.

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