Pakistan Textile Journal. april news

A comparative study of the properties of Denim fabrics made of ring, Open End and hybrid cotton folded yarns
by F. Zaghouani, M. Ben Hassen and M. Cheikhrouhou

Abstract: This article deals with the mechanical properties of Denim fabrics made of weft plied yarns of different categories. The authors studied the mechanical characteristics of fabric such as abrasion resistance; deformation; breaking load and fabric tear resistance and successfully obtained Denim fabrics with high rigidities, better tear characteristics, moderately sufficient tensile and elevated performance. The properties of Denim fabrics made of hybrid and ring plied yarns were very close. The results found were as follows: The breaking load of the hybrid Denim fabrics were close to those of the ring plied yarns, especially for the fabric of made of weft yarns Yd=100 tex. The hybrid plied yarns give a more important Denim fabric elongation than the Open End plied yarns. The abrasion cycles of fabrics made of weft hybrid plied yarns were nearer than the ring plied yarns. The tear resistances of Denim fabrics made of ring and hybrid plied yarns were very close.
Key words: Hybrid, Open End and ring plied yarns, Denim fabric, fabric tear resistance, the fabric elongation (%), the breaking load and fabric abrasion resistance.

Folded yarn is produced by twisting two or more single yarns together; many fabrics use plied yarns and in the recent years, researchers and industrial companies worldwide have been showing an increasing interest in rigid textile products, such as the Denim fabrics.

Denim fabric, the typical American contribution to the world of fashion, has its origin in Nimes, the textile town of France. Traditional blue denim is a warp-faced cotton fabric of indigo dyed warp and gray weft.

Today's denim fabrics are more of a social statement and have especially gained popularity since they provide comfort to people in their daily physical activities together with a certain luxury.

Several studies have discussed the fabrics properties, indeed, tensile strengths of woven fabrics have also been predicted by researchers through statistical models based on knowledge of the constituent yarns’ strength. But more realistic results could be obtained by considering frictional effects caused by interlacing yarn sizes and crimp levels.` [Shahpurwala.A.A et al (1989)].

Some uniaxial and biaxial strain models have been developed for woven fabrics either to analyze global fabric stress-strain responses and local geometric changes in processes involving crimp interchange, yarn flattening, yarn consolidation, jamming conditions and yarn extension, or to predict the stress-strain behaviors of woven fabrics differing in weave and yarn type, degree of tightness and thread spacing for both strain modes. [Realff, M.L(1997)].

[Scelzo et al (994)] have pointed that tear resistance can be increased by using yarns of a higher tensile strength in the fabric.

Yarn production is another structural parameter that significantly influences fabric behavior. Two strand Sirospun yarns have been proposed as an alternative to conventional two ply ring yarns in the worsted industry and the machine variables have the influence on yarn spinning geometry properties [Miao.M et al (1993)] and weaving performance [Plate (1982)].

[Emel.Önder et al (2003)] presented a comprehensive analysis of the mechanical properties of woven fabrics from 50/50 wool/polyester. He showed that the yarn structure is an important factor in determining fabric mechanical properties. The fabrics woven from Sirospun yarns are sufficiently tensile and tear resistant, less rigid and have good drape properties, but are more air permeable when compared with fabrics from conventional two-ply ring yarns.

Various methods used to produce woven fabric properties were presented. This study reports a comparison of different values of breaking load, fabric elongation, abrasion resistance and tear resistance of the Denim fabric made of ring, Open End and hybrid plied yarns.

Table 1 gives a summary of the cotton fibers characteristics used to produce the plied yarns has measured by the High Volume Instrument.

In this research, three types of plied yarns are discussed: the first, ring plied yarns (F-R) is composed of two ring spun yarns while the second, Open End plied yarns (F-OE) is composed of two Open End yarns and the third, hybrid plied yarns (F-OE/R) is formed with one ring spun yarn and one Open End Yarn.

Ring spun yarns (R) were produced on spinning machine type ZINSER 321. Autocorner Schlafhorst 338 was used for the operation of winding. Rotor yarns (OE) were produced by using Autocoro Schlafhorst of type ACO 240U/288. Assembly and folding operation were carried out respectively on"SSM" machine and the Two-for-one yarn folding machine Volkmann of the VTS-07 type with a constant speed.

The mechanical properties of plied yarn were tested by the USTER TENSORAPID whereas: unevenness, hairiness were controlled by using the USTER TESTER 3. Table II, given on the next page, provides a summary of the test results for ring, open-end and hybrid plied yarns.

The ring, open-end and hybrid plied yarns used for wefts of the Denim fabrics were successfully produced on Projectile machine of type Sulzer GROBAM EXTRA.

The ring warp yarns used were similar of the all types of Denim fabrics of linear density= 58,82 tex. Denim fabrics properties were tested after being washed according to ASTM 135-1973 III R.

We estimated the abrasion resistance of Denim fabrics by measuring the number of abrasion cycles according to ASTMD 4966. In fact the Denim fabrics were abraded in a Martindale abrasion tester under 9 kPa load. We also measured fabric tear resistance by Elmendorf with reference to ASTM D 1424-64.

The breaking load and the elongation of Denim fabric were tested by the INSTRON dynamometer (Grab test) according to ASTM D 1682-64.

With reference to these figures, we detect that the breaking load of fabrics is variable in the warp and the weft directions. Also, for all the fabrics categories, we notice that the warp resistance is upper than the weft resistance. This is due to the used of warp yarns which are glued and have a resistance upper than those of weft yarns. The warp resistance of all fabrics was found equivalent. Indeed, a common warp yarn for all the fabric was used.

The table 1 shows an advantage for the ring plied yarns with regard to the hybrid and Open End plied yarns. The breaking load of Denim fabrics in the weft direction depends fundamentally of the break resistance of weft yarns, this explains the fact that the Denim fabric from the weft ring and hybrid plied yarns are more resistant than those made by the weft Open End plied yarns.

The ring plied yarns used as weft yarns give a very important Denim fabric breaking load with the increase of weft linear density Yd (tex) by 24,65 %.

However, it is interesting to note that the properties of the hybrid Denim fabrics are close to those of the Ring plied yarns especially for the fabric of weft Yd=100 tex.

Referring to figures 4, 5 and 6, the warp elongation (%) of all categories of Denim fabrics is very close, because, we used the same type of warp yarns in fabrics.

The Denim fabric made of weft ring plied yarns are more flexible than the other fabrics, indeed, the elongation of Denim fabrics in the weft direction depends effectively on the elongation of weft yarns, this explains the fact that the Denim fabric from the weft ring plied yarns are more deformed than those made by the weft hybrid and Open End plied yarns. The ring plied yarns used as weft yarns give a very important Denim fabric deformation with the increase of weft linear density Yd (tex) of 80 to100 tex by 13,12 %.

However, it is remarkable to note that the elongation of the hybrid Denim fabrics are close to those of the Ring plied yarns especially for the fabric made of weft yarns of Yd=80 and 120 tex.

With regard to figure 7, the Denim fabrics have an abrasion resistance improvement by the increase of the weft yarn density of plied yarns. It was observed that with the increase of the yarn density, the number of abrasion cycles was improved by means of 24,12 %.

The comparison of the abrasion cycles of fabrics shows that the hybrid plied yarns used as weft yarns in the Denim fabric were more important than the Open End weft yarns made for fabric. For Yd equals to100 tex, the hybrid and the ring plied yarns give a close Denim fabrics abrasion resistance.

The plied yarns that have a very important degree of hairiness provide Denim fabrics that have more neps after abrasion, because there is less cohesion between fibers. The plied yarns Yd=80 and 100 tex have a great pilosity (table II), which give us a less Denim fabrics abrasion resistance than the other fabric types.

According to these figures, the values of warp tear resistance of all the Denim fabrics are close because a common warp yarn for all the fabric was used. However, in the direction of the weft, Denim fabric made from the weft hybrid plied yarns has a tear resistance upper than the Open End plied yarns of 15,80 % while increasing the weft linear density.

For the weft yarns of Yd =100 tex, Denim fabric from hybrid plied yarns has a very close tear resistance than the Ring plied yarns. With reference to the clarification of [Scelzo et al (1994)] the tear resistance is in direct relation with the Denim fabric resistance, indeed, the weft linear density increase and improves the tear quality of Denim fabrics.

The good quality of the Denim fabric is a result of weft plied yarn structure. In fact, the different types of plied yarns and their properties have several effects on the Denim fabric properties.

The major differences between the Denim fabrics are the linear density of weft plied yarns and their types. The Denim fabric made of weft ring plied yarns have the most important properties than the other types of fabric, this is due to the use of ring plied yarns which have an improvement of mechanical properties.

The hybrid plied yarns (weft Yd=80 tex and 100 tex) give a more important Denim fabrics elongation than the Open End plied yarns. The abrasion resistance of weft hybrid plied yarns fabrics were very important than the others fabrics. Tear resistance and breaking strength of Denim fabrics made of ring and hybrid plied yarns were very close.