**6. Experimental**

This chapter is focused on the effect of filament fineness, weft sett and weave type on air permeability of 100% polyester microfilament woven fabrics. Fabrics were made in three weave types; 1/1 Plain, 2/3 Twill (Z) and 1/4 Satin. The highest and the lowest weft sett values for the weave types were determined by production trials. For each weave type four different weft sett values were applied considering the weaveability limitations. For plain 30, 32, 34, 36 wefts/cm, for twill 41, 43, 45, 47 wefts/cm and for satin 43, 45, 47, 49 wefts/cm were determined as proper values. Polyester microfilament textured yarns of 110 dtex with 0.33, 0.57 and 0.76 dtex filament finenesses and conventional polyester textured yarns of 110 dtex with 1.14, 3.05 dtex filament finenesses were used as weft. For warp yarn 83 dtex polyester yarn with 1.14 dtex filament fineness was used. Warp set was 77 warps/cm for plain weave types and 85 warps/cm for twill and satin weave types. By this way 60 woven fabric samples were produced. Sample fabrics were woven by a loom with an electronic Dobby shedding mechanism and rapier weft insertion at a loom speed of 420 rev/min. Before desizing, to obtain dimensional stability, samples were applied to thermal fixation at 195ºC with 25m/min process speed.

Yarn linear density was measured according to ISO 2060, yarn tenacity and elongation were measured according to ISO 2062, shrinkage was determined according to DIN EN 14621, crimp contraction, crimp module and crimp stability were determined according to DIN 53840-1 standards. The properties of weft yarns are given in Table 1.

Figure 1, exhibits the microscopic views of cross sections of weft yarns used in the study. As seen from Figure 1, as the filament fineness decreases, the number of filament in yarn cross section increases. Thus, total void area between the filaments is smaller for finer filaments than that of coarser filaments. Furthermore, number of pores between the filaments and total surface area of the filaments is increased. The cross sections of the filaments are

Basically weft yarns must be inserted with the greatest care. In this respect, processing should be effected with at least two yarn storage units in order to keep taking off speed as low as possible. Warp ends should be fed by a finely controlled warp let off system with an absolute tension sensor and a positively controlled rotating back rest roller. Abrasion resistant materials must be employed to prevent filament breakage in the case of the winding unit. For this the use of vulcanized or rubberized materials are suggested. For double width weaving machines, an additional pressure roller should be used for fabric slippage. Textured filament yarns should be more intensively intermingled in order to ensure good running characteristics. This may however have a rather detrimental effect on air consumption in the case of air jet looms (Rupp & Yonenaga, 2000). The harness with drop wires of warp stop motion, the reed and the healds come into particularly intimate contact with microfiber yarns. The surfaces of these items, therefore, need to have particularly low roughness. Fabrics woven with microfiber yarns are often densely constructed; beat up must also be relatively severe. If the reed wires have sharp edges, they can easily cut the individual filaments and thus damage the yarn. Weft accumulators must provide sensitive gentle tensioning of fine yarns. Two or more weft accumulators must be used with weaving machines to reduce the withdrawal of weft insertion. Temples recommended for silk and silk like fabrics must be used for microfiber yarn fabrics in order

This chapter is focused on the effect of filament fineness, weft sett and weave type on air permeability of 100% polyester microfilament woven fabrics. Fabrics were made in three weave types; 1/1 Plain, 2/3 Twill (Z) and 1/4 Satin. The highest and the lowest weft sett values for the weave types were determined by production trials. For each weave type four different weft sett values were applied considering the weaveability limitations. For plain 30, 32, 34, 36 wefts/cm, for twill 41, 43, 45, 47 wefts/cm and for satin 43, 45, 47, 49 wefts/cm were determined as proper values. Polyester microfilament textured yarns of 110 dtex with 0.33, 0.57 and 0.76 dtex filament finenesses and conventional polyester textured yarns of 110 dtex with 1.14, 3.05 dtex filament finenesses were used as weft. For warp yarn 83 dtex polyester yarn with 1.14 dtex filament fineness was used. Warp set was 77 warps/cm for plain weave types and 85 warps/cm for twill and satin weave types. By this way 60 woven fabric samples were produced. Sample fabrics were woven by a loom with an electronic Dobby shedding mechanism and rapier weft insertion at a loom speed of 420 rev/min. Before desizing, to obtain dimensional stability, samples were applied to thermal fixation at

Yarn linear density was measured according to ISO 2060, yarn tenacity and elongation were measured according to ISO 2062, shrinkage was determined according to DIN EN 14621, crimp contraction, crimp module and crimp stability were determined according to DIN

Figure 1, exhibits the microscopic views of cross sections of weft yarns used in the study. As seen from Figure 1, as the filament fineness decreases, the number of filament in yarn cross section increases. Thus, total void area between the filaments is smaller for finer filaments than that of coarser filaments. Furthermore, number of pores between the filaments and total surface area of the filaments is increased. The cross sections of the filaments are

to prevent the fabric bowing out in the selvedge zone (Basu, 2001).

53840-1 standards. The properties of weft yarns are given in Table 1.

**6. Experimental** 

195ºC with 25m/min process speed.


essentially round. But after the texturizing process the view of the filament cross section was changed to cornered shape.

Table 1. Weft yarn properties used in the study

Fig. 1. Microscopic views of weft yarn cross sections by magnification X200

Structural properties of sample fabrics after thermal fixation and desizing processes were determined according to following standards and results were given in Tables 2, 3 and 4.


**Weave type** 

**1/4 Satin** 

**Weft yarn filament fineness, dtex**

Polyester Microfilament Woven Fabrics 167

**Fabric weft sett, wefts/cm**

Figure 2 shows the SEM views of three of fabric samples which have the highest weft sett

 (a) (b) (c) Fig. 2. SEM views of fabric samples X 100 with 0.33 dtex weft yarn filament fineness and 1.14 dtex warp yarn filament fineness (a) Plain, 36 wefts/cm, 77 warps/cm, (b) Twill, 47 wefts/cm, 85 warps/cm, (c) Satin, 49 wefts/cm, 85 warps/cm

All yarn and fabric samples were conditioned according to ISO 139 before tests and tests were performed in the standard atmosphere of 20±2ºC and 65±4% humidity. The air permeability of sample fabrics was measured by SDL Atlas Digital air permeability test device according to ISO 9237 with 20 cm² test head and 200 Pa air pressure drop. Each

3.05 42 **43** 85 129 0.23 1.14 42 **43** 85 129 0.22 0.76 42 **43** 85 128 0.22 0.57 42 **43** 85 130 0.22 0.33 42 **43** 85 130 0.22 3.05 44 **45** 85 132 0.23 1.14 44 **45** 85 131 0.22 0.76 44 **45** 85 132 0.22 0.57 44 **45** 85 133 0.22 0.33 44 **45** 85 133 0.23 3.05 46 **47** 85 133 0.23 1.14 46 **47** 85 132 0.23 0.76 46 **47** 85 134 0.23 0.57 46 **47** 85 136 0.22 0.33 46 **47** 85 136 0.23 3.05 48 **49** 85 136 0.23 1.14 48 **49** 85 139 0.22 0.76 48 **49** 85 138 0.23 0.57 48 **49** 85 140 0.23 0.33 48 49 85 138 0.23

**Fabric warp sett, warps/cm**

**Fabric weight, g/m²**

**Fabric thickness, mm** 

**Adjusted weft sett, wefts/cm**

Table 4. Structural properties of satin weave sample fabrics

and lowest weft yarn filament fineness.


Table 2. Structural properties of plain weave sample fabrics


Table 3. Structural properties of twill weave sample fabrics

**Fabric weft sett, wefts/cm**

3.05 28 **30** 77 117 0.25 1.14 28 **30** 77 112 0.23 0.76 28 **30** 77 111 0.23 0.57 28 **30** 77 113 0.24 0.33 28 **30** 77 114 0.24 3.05 30 **32** 77 118 0.24 1.14 30 **32** 77 116 0.23 0.76 30 **32** 77 115 0.22 0.57 30 **32** 77 116 0.22 0.33 30 **32** 77 117 0.22 3.05 32 **34** 77 119 0.24 1.14 32 **34** 77 120 0.22 0.76 32 **34** 77 118 0.21 0.57 32 **34** 77 120 0.22 0.33 32 **34** 77 121 0.22 3.05 33 **36** 77 121 0.23 1.14 33 **36** 77 122 0.22 0.76 33 **36** 77 120 0.21 0.57 33 **36** 77 121 0.22 0.33 33 **36** 77 123 0.21

**Fabric warp sett, warps/cm**

**Fabric warp sett, warps/cm**

**Fabric weight, g/m²**

**Fabric thickness, mm** 

**Fabric weight, g/m²**

**Fabric thickness, mm** 

**Adjusted weft sett, wefts/cm**

Table 2. Structural properties of plain weave sample fabrics

Table 3. Structural properties of twill weave sample fabrics

**Adjusted weft sett, wefts/cm**

**Fabric weft sett, wefts/cm**

3.05 40 **41** 85 125 0.22 1.14 40 **41** 85 128 0.22 0.76 40 **41** 85 126 0.22 0.57 40 **41** 85 129 0.22 0.33 40 **41** 85 130 0.22 3.05 42 **43** 85 128 0.22 1.14 42 **43** 85 130 0.22 0.76 42 **43** 85 130 0.22 0.57 42 **43** 85 132 0.22 0.33 42 **43** 85 133 0.22 3.05 44 **45** 85 131 0.22 1.14 44 **45** 85 133 0.22 0.76 44 **45** 85 132 0.22 0.57 44 **45** 85 135 0.22 0.33 44 **45** 85 137 0.23 3.05 46 **47** 85 134 0.23 1.14 46 **47** 85 136 0.22 0.76 46 **47** 85 136 0.22 0.57 46 **47** 85 138 0.23 0.33 46 **47** 85 141 0.23

**Weft yarn filament fineness, dtex**

**Weave type** 

**Plain** 

**Weave type** 

**2/3 Twill (Z)** 

**Weft yarn filament fineness, dtex**


Table 4. Structural properties of satin weave sample fabrics

Figure 2 shows the SEM views of three of fabric samples which have the highest weft sett and lowest weft yarn filament fineness.

Fig. 2. SEM views of fabric samples X 100 with 0.33 dtex weft yarn filament fineness and 1.14 dtex warp yarn filament fineness (a) Plain, 36 wefts/cm, 77 warps/cm, (b) Twill, 47 wefts/cm, 85 warps/cm, (c) Satin, 49 wefts/cm, 85 warps/cm

All yarn and fabric samples were conditioned according to ISO 139 before tests and tests were performed in the standard atmosphere of 20±2ºC and 65±4% humidity. The air permeability of sample fabrics was measured by SDL Atlas Digital air permeability test device according to ISO 9237 with 20 cm² test head and 200 Pa air pressure drop. Each

Figure 3 exhibits the air permeability of plain weave samples for different filament fineness and weft sett. The highest air permeability value is 71.2 mm/sec and the lowest value is 10.2 mm/sec. As seen from Figure 3, increasing weft sett values cause a decrease of air permeability values for plain weave samples. Higher weft sett values provide the gaps between the yarns which the air pass through to become smaller thus lead to lower air permeability. The literature survey shows that some former studies on this topic (Fatahi & Yazdi, 2010; Çay &Tarakçoğlu, 2008; Çay &Tarakçoğlu, 2007) are agree with our work. Nevertheless, it must be considered that the effect of weft sett on air permeability is more obvious for coarser filaments. In other words the influence of weft sett on air permeability decreases as the filament fineness decreases. On the other hand lower filament finenesses cause lower air permeability. Because, lower filament fineness results in higher number of filament in yarn cross section. Thus, dimensions of gaps between the filaments within the yarns decreases. This is an expected result, since micro voids between the fibers become smaller as the fiber diameter decreases, thus the air permeability decreases as pointed out in

The statistical analyses show that the best fitting model is the cubic model for plain weave type. ANOVA results for air permeability of plain weave type samples is given in

> **Mean Square**

**Model** 7541.65 7 1077.38 637.04 < 0.0001 Significant **A** 635.42 1 635.42 375.72 < 0.0001 Significant **B** 261.96 1 261.96 154.89 < 0.0001 Significant **A2** 90.57 1 90.57 53.55 < 0.0001 Significant **B2** 280.35 1 280.35 165.77 < 0.0001 Significant **AB** 1174.29 1 1174.29 694.34 < 0.0001 Significant **A2B** 118.57 1 188.57 70.11 < 0.0001 Significant

**Lack of Fit** 47.25 12 3.94 11.46 < 0.0001 Significant

ANOVA results in Table 5 show that the effect of filament fineness (A) and weft sett (B) on

Air Permeability (mm/sec) = 36.02279 + 450.27578 A + 1.132469 B + 47.20693 A2

In this equation (1); A and B are the filament fineness (dtex) and weft sett (wefts/cm) independent variables respectively. The air permeability of plain weave polyester

+ 0.053972 B2 - 29.40924 AB – 1.35053 A2B + 0.47562 AB2 (1)

**F** 

**value P value Significance** 

an earlier study (Varshney, 2010).

**Source Sum of** 

**squares** 

**Degree of freedom** 

**AB2** 138.09 1 138.09 81.65

Table 5. ANOVA results for air permeability of plain weave type samples

air permeability is significant for plain weave samples from a statistical approach.

The regression equation of the cubic model for plain weave type is as follows:

**Residual** 54.12 32 1.69

**Pure Error** 6.87 20 0.34

**Cor. Total** 7595.77 39

Table 5.

sample was replicated twice and ten repeated measurements were done for each replication. The mean values of the test results were used in graphical representation.

Design-Expert statistical software package was used to interpret the experimental data and to compose the regression models. Regression models were formed to define the relationship between independent variables (filament fineness and weft sett) and response variable (air permeability) for plain, twill and satin weave types. General Factorial Design was selected to compose regression models. The air permeability test results of samples were used to analyze the general factorial design. The analysis of variance, lack of fit tests and residual analysis were performed to select the proper model for the air permeability.
