The effects of hollow yarn and fabric structure on permeability and moisture management properties of woven fabrics

Abstract In this work, the effects of weft yarn (two plied, two plied cotton/PVA, siro core spun, and ring core-spun weft yarn) and fabric structure (plain, twill, and sateen construction) on air and water vapor permeability, vertical wicking height, and moisture management properties of the fabrics were analyzed in detail. The scope of the research was to obtain better performance by producing hollow and microporous structures.


Introduction
Today, new product research recontinues in the field of both apparel and home textiles.Not only the product's design and fashion parameters but also performance characteristics are effective in choosing a product.Comfort expectations in apparel products contain many components, they need to provide both physical and psychological comfort.Thermal comfort, soft handle, high absorbency, easy cleaning, etc. as functional properties can be given as an example in home textiles.
The parameters affecting the comfort property are fiber type and structure, the yarn type, fabric construction, and finishing processes.When the previous studies are reviewed, it can be seen that especially the fiber type, fiber structure, yarn structure, and the applied finishing processes of textile materials are investigated.
The hydrophilic and thermal comfort properties of fabrics have been studied by many researchers.Various researchers have stated that bio-polishing is applied to the fabric (Eker, 2011), surface treatments such as plasma (Ozdogan, 2006) and innovative finishing techniques in pretreatment (Perincek, 2006) positively affect the hydrophilicity of the fabric.The effects of yarn and fabric structure on fabric hydrophilicity have been investigated by different researchers.The effects of yarn and fabric structure on the absorbency properties of knitted fabrics (Legersk a et al., 2020;Ozgen & Altas, 2014) and woven fabrics (Namligoz et al., 2010;Saricam & Kalaoglu, 2014;Yuksel & Okur, 2011) were investigated.When the hydrophilic properties of fabrics with a pile surface were examined, it was seen that pile structure, pile height, and the finishing processes they saw affected absorbency (Oner, 2008;Unal, 2007).Ozdil (2007) studied comparing the thermal comfort properties of socks made from different raw materials and it was stated that porosity affects the air permeability value, and socks with a raw material blend have lower water vapor permeability than 100% cotton socks.Ozdil et al. (2009) investigated the moisture transmission properties of single jersey fabrics produced using cotton yarns produced in different yarn counts and twist coefficients.It was determined that a more compact structure was obtained with a high twist coefficient, while the absorption speed, spreading speed and maximum spreading area decreased, but the wetting time increased, and the increase in yarn fineness had an opposite effect on all these values.
The liquid transport mechanism depends on the effect of capillary forces and surface characteristics.As the spaces between the fibers narrow, the moisture drainage ability of the textile material increases.The fabric structure absorbs moisture easily when the narrow capillaries form is effective (Baltu snikait_ e et al., 2014).It is considered that the existence of air gap within the yarn structure can affect the transmission features of fabric (Mukhopadhyay et al., 2011).Fangueiro et al. (2009) investigated the performance of knitted fabrics obtained from functional yarns produced by blending wool and moisture management fibers such as Coolmax and Finecool.It was found that fabrics with Coolmax showed the highest performance properties, while fabrics with wool showed low water absorbency properties, but had a high drying rate.
Especially by using water-soluble fibers, hollow core spun yarns give positive results in terms of moisture transmission and comfort.It is stated by many researchers that the textile product having hollow or microporous structures gives affirmative results when using the staple fibers or filament yarns of polyvinyl alcohol (PVA).Mukhopadhyay et al. (2011) investigated the thermal comfort properties of single jersey fabrics produced from the ring and siro core spun yarns (80/20 cotton/PVA).When entire thermal comfort properties were evaluated, the values of hollow siro spun yarns were found to be better.It has been stated that the only advantage of sirospun yarn over ring yarn is the increase in water vapor permeability.Sharma et al. (2016) investigated moisture transmission changes after removing the cotton from the knitted fabrics produced with 100% PET (polyester) and 80/20 PET/cotton blended ring and vortex spun yarns.It was observed that while the properties of the modified fabric such as air permeability and water vapor permeability improved, its absorption ability decreased.The liquid absorption and general absorption properties of the fabrics produced with vortex yarns are lower than ring yarns, while air and water vapor permeability is better.Different properties such as weight, thickness, pilling, air, and water vapor permeability, capillary absorbency, and thermal comfort properties of fabrics knitted from yarns containing different PVA ratios with the ring core spun yarn production technique were investigated by various researchers (Aytac, 2016;Aytac & Gurkan Unal, 2018;Celep & Yuksekkaya, 2016).It has been stated that fabrics with different sizes of gaps obtained by changing the PVA ratio have a more voluminous structure, better thermal comfort properties, and faster water absorption time than fabrics produced with conventional ring yarns (Alasehirli, 2009;Celep, 2015).Ishtiaque et al. (2008), investigated the effects of microporous woven fabric structure on bending properties, tensile properties, weight, air permeability, and moisture vapor transmission rate by producing staple PVA fiber and cotton blend yarns.Lolaki et al. (2017) investigated the fabric density, fabric weight, air permeability, and fabric porosity values by producing sateen woven fabrics using cotton-PVA siro core spun yarns and PVA folded with double ring yarn in the weft.Gao et al. (2022) produced different multilayer fabrics and compared their thermal wet comfort properties with plain knitted fabrics.According to their results, the fabric produced with profiled polyester and low proportion of cotton as the inner layer and a high proportion of modified PEA (modified polyacrylate fiber) and viscose as the hygroscopic exothermic layer have better moisture management characteristics and evenly distributed hygroscopic heat generation.
There are comprehensive studies on the effects of hollow and microporous yarn structure in knitted fabrics by comparing different yarn properties, fabric structures, and raw materials.However, there are few studies on woven fabrics produced with hollow yarns.In this study, the effects of yarn structure and woven fabric construction on air and water vapor permeability, vertical wicking height, and moisture management properties were analyzed in detail.

Material and method
In this paper, the air permeability, water vapor permeability, moisture management, and hydrophilicity properties of 12 different samples in plain, twill, and sateen fabric structures with 4 different weft yarns were examined in detail.
The study's main purpose is to develop fabric structures with increased functionality that can be used for different purposes in both apparel and home textile production by using the hollow yarn structure in the weft.It is aimed to examine the effects of the yarn production method and weaving construction on the comfort properties of fabrics containing 100% cotton hollow weft yarns, produced with different methods and removing PVA multifilament by washing.The experimental plan was given in Table 1.
Due to the long float lengths in sateen and twill fabrics, the effect of weft yarns on the fabric surface is aimed to be increased compared to the plain fabric.Subsequently, the fabrics have been washed and the PVA filament has been dissolved to obtain hollow yarn structures.The final yarn count (59 tex) and the sheath-core ratio (88%-12% cotton/PVA) have been kept constant.The washing process was performed to dissolve the PVA yarn.The experimental plan and fabrics' codes are given in detail in Table 1.
All test samples were conditioned for 24 h in standard atmospheric conditions (20 C ± 2 temperatures, 65 ± 4% relative humidity) according to TS EN ISO 139.The hydrophilicity measurement was made according to the DIN 53924 (testing of textiles À velocity of soaking water of textile fabrics (method by determining the rising height) standard).Three samples were taken from different parts of the fabric in the weft and warp directions and the average was recorded.The vertical wicking height (mm) in the 30th, 60th, and 90th second was recorded.Three measurements were made from each fabric sample in the weft and warp directions (5, 15, 30, 60, 90, 120, 150, 180, 210, 240, 270, and 300 s).Air permeability values of fabrics were measured in TEXTEST Instruments/FX3300 device according to TS 391 EN ISO 9237 standard.The measurement was made under a 20 cm 2 area and 100 Pa pressure.In the study, water vapor permeability was made in the Permetest device according to ISO EN 31092 standard.For testing the liquid moisture transport capabilities of the fabrics, the Moisture Management Tester (MMT) was used and the tests were performed according to the AATCC Test Method 195-2012.
Origin Pro 2023 Graphing & Analysis Programme was used for graphs and SPSS 18.0 statistical program was used to evaluate the test data obtained in the study.The results were evaluated by applying a one-way analysis of variance (one-way ANOVAanalysis of variance) to examine the effect of fabric structure and weft yarn structure used on fabric properties.In addition, the differences between the groups were examined by applying the Student-Newman-Keuls test and the Tamhane T2 test, whether the variances were equal or not.

Results and evaluation
The effects of the weaving construction and the weft yarn property on the air permeability, relative water vapor permeability, Plain weave a Twill a Sateen a Two-plied yarn (100% cotton) Warp density 20 threads/cm, weft density 15 threads/cm.vertical wicking height (in the weft and warp direction), and moisture management properties were investigated and variance analysis results are given in Table 2.

Air permeability
Air permeability, the breathability of the fabrics, is affected by fabric parameters such as weaving construction, porosity, thickness, weft and warp density, yarn count, and hairiness.Yarn properties were given in Supplementary Appendix 1.The rate of airflow passing through the fabrics is measured and the effect of fabric and weft yarn structure was found to be statistically significant (Table 2).The air permeability of the fabrics increased in plain, twill, and sateen fabrics, respectively (Figure 1).The differences between them were also found statistically significant compared to the multiple comparisons.It can be considered that the air permeability is increased as longer float lengths can provide wider gaps for air passage.
(Tamhane T2) test.According to the fabric weight, density, and thickness evaluation results, the weight values of plain fabrics were found to be higher than the others.Although fabric density in the warp direction was lower than the others, it was found to be highest in the weft direction.Therefore it is thought that the air permeability value is lower than other weaving constructions.
Within plain fabrics, according to weft yarns type, the air permeability values from the highest to the lowest are listed as siro core spun, two-plied yarn, plied yarn (two plied cotton þ PVA), and ring core-spun yarn.The difference between them was found to be statistically significant.
For twill fabrics, the lowest air permeability value was obtained when ring core-spun weft yarns were used, while the highest air permeability values were obtained when plied yarn (two plied cotton þ PVA) was used.The difference between them is statistically significant.When the effect of weft yarn type on the air permeability values of the fabrics in the sateen fabrics is examined; they are listed as plied yarn (two plied cotton þ PVA), ring core spun, siro core spun and two-plied yarn, from the highest to the lowest.According to these results, the difference between the groups was found to be statistically significant.
It was not possible to generalize the effect of weft yarn type for air permeability according to the test results.But the highest air permeability was obtained when plied (two plied cotton þ PVA) microporous weft yarn structure was used in sateen fabrics, while the lowest was obtained with ring core spun yarn in plain fabrics.It is thought that the higher hairiness of ring yarns than the others reduces the air permeability values (Figure 2).

Relative water vapor permeability
Good water vapor permeability of a fabric, transmits the vapor perspiration at the skin surface, is affected by the porosity, thickness, weight, and fiber properties of the fabric.According to the analysis of variance, the effect of the fabric structure on the relative water vapor permeability value was found to be statistically significant, however, the effect of weft yarn type is not significant (Table 2).Besides, the water vapor permeability of hollow yarns is slightly higher than the two plied yarn (Table 2, Figure 3).Contrary to a previous study, siro spinning system did not increase water vapor permeability compared to ring yarns (Mukhopadhyay et al., 2011).The difference between the values of sateen and twill fabrics was not significant, but the difference between the values of these fabrics and plain fabrics was statistically significant.The highest relative water vapor permeability value was found in the plain fabrics, in contrast to the air permeability (Figure 3).In sateen and twill fabrics, weft yarns make long floating height on the fabric surface (Figure 2).Although the plain fabrics' weight is higher than the others, the density in the warp direction was found to be slightly lower, and therefore, it is thought that moisture transmission through fibers is higher than other fabric types due to higher porosity and higher weft-warp yarn connections.

Water absorbency and vertical wicking properties
Yarn intersections in the fabric contribute to the capillary movement of fluids rather than large pores by acting as a reservoir and providing flowing to all capillar branches equally.The more regular the gaps in the fabric structure, the better the transmission of the fluid.The use of PVA in the yarn structure and its removal creates gaps of different sizes in the cross-section of the yarn.Vertical wicking height shows the movement of water in the fabric as capillaries and is related to yarn geometry (spaces within and between yarns) (Chen et al., 2016).The vertical wicking height (mm) is measured in time (at the end of 5, 15, 30, 60, 90, 120, 150, 180, 210, 240, 270, and 300 s).It was observed that due to the high hydrophilicity, the rising continues after 300 s and does not reach a stable state.The vertical wicking height values after 30, 60 and 90 s were given in Figure 4.The effect of weave construction on vertical wicking height values (warp and weft directions) was found to be statistically significant (Table 2).However, the effect of weft yarn type on fabric vertical wicking height values in both weft and warp directions was not found statistically significant (Table 3).
According to the results of the multiple comparison test (Tamhane 2), the highest hydrophilicity was found in sateen and twill fabrics (warp and weft directions).The difference between them was not statistically significant but the difference between plain fabrics and these fabrics was found significant.
Since the effect of the weave construction (warp and weft direction) was found significant, an additional evaluation was made for each construction to determine the effect of the weft yarn type.According to the analysis of variance, the effect of  the weft yarn type on the hydrophilicity values of the all fabrics (warp and weft directions) was not found statistically significant.The effect of the fabric construction can be more prominent as all yarns are 100% cotton and the difference between them is very meager (Figure 4).Besides, the vertical wicking height the warp direction was slightly higher than in the weft direction, depending on time.Due to the hollow yarn structure, it is thought that the progress of water through the fiber channels is slower than the two plied yarns.In a previous study on water absorbency in terry cloth, it was stated that although untwisted pile yarns cannot transmit water through the fiber channel in the yarn, they absorb the same amount of water as a result, but the duration is different (Cruz et al., 2017).

The results of moisture management properties
The moisture transport through the fabric under transient humidity conditions is an important factor that inspirations the comfort of the user.Scientific understanding of the moisture management properties for the design of products is important in terms of clothing and comfort.(Das et al., 2007;Supuren et al., 2011).While the effect of fabric construction on water absorbency values was found to be significant according to the results of the vertical wicking height test, the effect of the weft yarn production technique was not found statistically significant.Considering that examining the effects of hollow yarn structure on moisture management properties of fabrics would be beneficial for product design, measurement was also made with a moisture management test device (MMT).To see the effect of the yarn structure, an additional evaluation was made for the each fabric structure and yarn type to see the effect of the fabric structure.
In the MMT test, the top and bottom wetting times (s) of the fabrics give the time when the fabrics start to get wet.The absorption rate (%/s) shows the average moisture absorption ability and is related to the material's surface properties.The spreading velocity (mm/s) is calculated by using the maximum lower and upper wetting radius (mm) values.The OMMC value, which shows the total moisture management capacity, is a value calculated using these values, and the higher it is, the higher the liquid moisture transmission ability of the fabric (Supuren et al., 2011).
To see the effect of weft yarn structure on moisture transmission properties, a one-way analysis of variance (one-way ANOVA) was applied for each fabric (Table 3), and the effect of yarn structure was found to be statistically significant.
Wetting is the initial part of fluid spreading and the characteristics of the wetting liquid and the surface energy of the textile product affect the wetting.The surface energy of the textile products depends on fiber properties (fiber structure, cross-sectional shape, surface purity, and roughness of fiber surface), yarn properties, fabric properties, capillary forces, cover factor, fabric density, and surface roughness.On the other hand, arranging of the fibers or yarns into a fabric, the capillary radius, the number of capillaries formed and tortuosity of the channels within the material, water absorption capability of fiber affect the wicking.(Tang et al., 2014) The effect of weft yarn structure on the moisture management properties of plain fabrics was found to be significant for the other values except max wetted radius (top and bottom).When the results for twill fabrics were examined, the effect of weft yarn structure on moisture management properties found to be statistically significant except for the lower wetting time, upper absorption rate, and upper largest wetting diameter values (Table 3).According to the results of variance analysis of the effect of weft yarn structure on the moisture transmission properties of sateen fabrics; the effect on the other results was found to be statistically significant except for only the upper wetting time and the max wetted radius bottom values (Table 4).Surface wetting time shows the time when the upper and lower surfaces of the fabrics start to get wet, and the shorter it is, the sooner the fabric absorbs water.If this time is less than 3 s, the wetting rate is called 'very fast' (Chen et al., 2016).When the plain weave structure is used, the lowest wetting time of the upper surface is obtained when the ring core spun weft yarns (3 s) are used, while a similar result is obtained for the wetting time of the lower surface (3.46 s).When the time for the wetting of the bottom fabric surface of plain fabrics is examined, it is seen that the values of the fabrics produced from plied yarns (two plied cotton þ PVA) are the longest.For the bottom wetting times, the difference between the fabrics using two plied yarns was significant.The wetting times of the fabrics using two plied yarns are the longest.In this case, it can be said that when hollow yarns are used, water is absorbed from the top surface to the bottom surface in a shorter time.
In sateen weave, the weft yarns dominate on fabric surfaces more than other weaving structures.It can be said that although the top wetting time is lower for two-plied weft yarns, hollow yarns transmit water to the bottom more quickly in this study.The findings support the results of vertical wicking height.
The absorption rate is the initial slope of the curves of the water contained in the material.When it is between 50 and 100 (%/s), it shows a high water absorption rate (Chen et al., 2016).Only the fabrics using two plied yarn (34.12%/s) have the lowest value.The difference between them was found to be statistically significant.The top and bottom absorption rate (%/s) is higher in microporous fabrics produced using plied weft yarn (two plied cotton þ PVA) compared to the others.
Accumulative one-way transport index R values are calculated by the device and are the difference in the total moisture saturation between the two sides of the fabric.As stated in the user manual of the MMT device, it is stated that 'good/excellent accumulative one-way transport index R-value should be used for fabrics that provide moisture management.A low accumulative one-way transport index R-value should be used for fastabsorbing and fast-drying fabrics'.The moisture management test results were evaluated according to a five-grade scale in the given AATCC Test Method 195-2012(Baltu snikait_ e et al., 2014).When the results were examined; the value of the sateen fabric, in which the two plied weft yarns were used, was found to be the lowest (R ¼ 45).On the other hand, the highest value was obtained when the ring core spun weft yarns were used Table 3.The moisture management properties of fabrics (MMT) (Baltu snikait_ e et al., 2014;Supuren et al., 2011).(R ¼ 132) and for plain fabrics where the siro core spun weft yarns were (R ¼ 131).According to the AATCC standard, the lowest R value of the fabric sample is Grade 1, weak (<50), while the other two fabric samples are grade 3, good (100-200, good).When the twill structure is used, the accumulative oneway transport index R values for the other types except for plied (two plied cotton þ PVA) weft yarn (R ¼ 113, good) is considered as 2nd degree, medium (50-100).If a generalization is made according to the results, when hollow yarns are used in the weft in sateen fabrics, the accumulative one-way transport index R values are considered to be good.
As the total moisture management capacity (OMMC) value, which is calculated by the device from the parameters of the accumulative one-way transport index R-value and the moisture drying rate of the fabric, increases the ability of total transport increases as well.When the results were examined, the lowest OMMC value was found for the sateen fabrics in which two plied weft yarn was used (OMMC ¼ 0.29), and it was evaluated as 2nd degree, medium (0.2-0.4,medium) according to the AATCC standard.The highest values were obtained when plied (two plied cotton þ PVA) weft yarns (OMMC ¼ 0.52) in sateen structure and siro core spun yarns (OMMC ¼ 0.51) in plain structure, were used.According to the AATCC standard, the results of both fabric samples are evaluated as 3rd degree (good) (0.4-0.6).The results of all fabric samples were found to be 3rd degree (good) in plain fabrics, and 3rd degree (good) when hollow yarns were used for satin fabrics.When the twill weave structure is used, the result is again qualified as 3rd degree (good) except for the fabric sample using ring core spun yarn.

Conclusion
The effect of the weft yarn structure and weaving structure on air permeability, water vapor permeability, vertical wicking height (hydrophilicity), and moisture management properties of the fabrics in three different weaving constructions, produced using hollow yarn and microporous yarn structures were examined.The effect of weave structure was found to be significant for all tested properties.After washing for removing PVA multifilament, the density values in the weft and warp directions increased and therefore the weight of the fabric increased due to shrinkage for all fabric types, and the values of plain fabrics were found to be higher than the other fabrics.While the air permeability and vertical wicking height (hydrophilicity) values in the weft and warp directions of the sateen and twill fabrics were found higher than the plain fabrics, the water vapor permeability values were found to be lower.
The effect of the weft yarn structure on the air permeability value was found to be significant, but contrary to the other studies, the effect on water vapor permeability and capillarity was not found to be significant in the warp and weft direction.It is thought that all of the fabrics are 100% cotton, the density values are very close to each other and the difference between them is not found statistically significant.For sateen and twill structures, the highest air permeability values were obtained when the plied yarn (two plied cotton þ PVA) microporous yarn structure was used in the weft.Among the hollow yarn structures, the lowest air permeability value was obtained when ring core spun yarns with higher yarn hairiness values were used.
The efficiency of liquid transport in textile products is an important factor affecting the physiological comfort of users.The effect of weaving structure and weft yarn type on the moisture management properties was found to be significant.Better results are obtained when plied (two plied cotton þ PVA) microporous weft yarn structure is used for all fabric types, regarding to wetting times, absorption rate, maximum wetting radius, and spreading speed.It is thought that if a hydrophobic fiber is preferred instead of 100% cotton, the effect of the hollow yarn structure will be observed more clearly.In previous studies, it has been stated that moisture transmission is faster due to the microporous structure and lower packing density (Chandrasekaran et al., 2018;Mukhopadhyay et al., 2011).In a study conducted for the hollow yarn structure produced by the siro-spun method, it was stated that better thermal conductivity, wicking capacity, air permeability, and water vapor permeability values were obtained compared to the hollow yarn structure produced by the ring method (Mukhopadhyay et al., 2011).In this study, it has been observed that the results vary depending on the fabric structure, but when the water vapor permeability and vertical wicking in the weft direction are considered, hollow siro-spun yarns for all fabric structures give better results than those produced by the ring method.On the other hand, in terms of OMMC, ring core spun hollow yarns in sateen fabrics showed better results than siro core spun hollow yarn structures.
The porous or hollow yarn structure has been found to provide better water and air permeability, wicking and moisture management properties to fabrics.Fabrics should be facilitating the transport of liquid away from the skin and evaporation of liquid to the outside environment.While the microporous structure stands out in terms of moisture management, significantly better results have been observed in sateen fabrics, where the modified structure is more effective on the fabric surface, compared to other fabric structures.It is thought that it would be beneficial to keep these results in mind when designing products with improved functional properties for clothing or home textiles.

Disclosure statement
No potential conflict of interest was reported by the author(s).

References
Alasehirli, G. ( 2009).An investigation of hollow yarn manufacturing techniques on ring spinning machine and evaluation of yarn

Figure 2 .
Figure 2. Images of plain, twill and sateen fabrics woven with different weft yarns after washing (Leica microscope).

Figure 3 .
Figure 3.The results of water vapor permeability.

Figure 4 .
Figure 4.The vertical wicking height values of plain, twill and sateen fabrics (mm/s) in the weft and warp direction.

Table 1 .
The experimental plan and fabrics' codes.

Table 2 .
The effect of weaving construction and weft yarn structure on air permeability, relative water vapor permeability, and hydrophilicity (analysis of variance).
Figure 1.The air permeability test results.

Table 4 .
The effect of yarn type on moisture management properties of fabrics (one-way variance analyses).