Porosity knitted spatial structure, and future trends

Vojislav Gligorijevic1, Jovan Stepanovic1, Vasilije Petrović2, Nenad Ćirkovic1

University of NisFaculty of Technology Leskovac1

Technical fakulet "Mihajlo Pupin" Zrenjaninu2

Abstract Spatial knitting different types with similar structures are produced on machines Shima Seiki fineness 7. In order to achieve different porosity knitting in order to achieve different porosity, capillary radii and angle of capillaries on a horizontal surface were changed to a different number of space between two rows of yarn single jersey knitting, as well as varying the space between two consecutive rows trap. Capillary radii were calculated using the model and porosity based on the weight of the sample knitting, thickness and surface area 50.26 cm2. Vertical absorption tests were performed on eleven samples using a knitting machine for testing the absorption of records found. The rate of absorption and total absorption was compared with the theoretical parameters of twists and apsorpcijom.Samples knitting with higher porosity have higher total absorption in contrast to the samples with lower porosity and lower overall ability absorption. However, knitting patterns with lower capillary radius and high capillary angle (sin φ) on the horizon absorption.Total show lower rates of absorption per unit area seems to vary with the thickness of knitting, knitting thicker higher overall absorption per unit area. Total absorption varies from 800% to 1 500% and that the rate of absorption of some structures is very high in comparison with other structures. The future of the textile structures can be produced in water in geo-textiles, agro-textiles and clothing materials under different conditions in agriculture drop by drop.

Key words: knitted structure, porosity, structure, absorption, corner of capillaries, capillary radii, geo-textiles, agro textiles.

Introduction

In the process of wearing garments made of knitted and transverse spatial Basics of knitted knittig is one of the key factors that influence the physiological wear comfort is the transfer of liquids or moisture in the knitting.Knittig to quickly transfer moisture / liquid away from the skin surface carriers feel more comfortable and keep the skin dry. At high levels of physical activity, such as athletes , when there is an extensive body perspiration , it is not only desirable for the knittig next to the skin to absorb liquid faster, but that has been passed down through the mesh immediately in order to avoid the nuisance of knitting that sticks to the skin. To avoid this unpleasant occurrence, comfort of the knittig can be improved by understanding the mechanism of liquid transfer.Mathematical modeling of surface tension transmission flow in the yarn and knitting can provide a way to develop such an understanding. In capillary flow through knitting, yarn and its composition are responsible for the major part of the liquid stocks (Hollies et al. , 1956, 1957).For these above reasons Vresna are many researches to study the behavior of the liquid in the spatial structure of the knit. This also applies to the basics and simple cross woven knittig. Among the extensive research in this area, the yarn is treated as a porous media ( Amico, 2000, 2002 ), or as a transfer fluid that can be described by Darcy's law ( Rahl et al. , 1997, Chatterjee, 1985), or as a capillary tube ( id Kamath, 199. Nioni, 2006 Pervelz et a., 2000, 2001 and Washburn,1921) through which the liquid can model - Lucas - Washburn kinetics ( Washburn , 1921 ). In the first case , however, the characteristic parameters, such as permeability are difficult to quantify and are always obtained empirically ( Benltoufa et al. , 2007).In another, somewhat similar, the effective radius of the capillary tube, the effective contact angle, etc. , are also determined by placing the experimental data. An extensive review of the literature in this area shows that, although widely to the research in this area, a comprehensive model to simulate capillary flow through the fabric of the structural parameters is still missing.

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The current transport properties

Transfer the liquid through the knitwear is usually in two stages. First, wet the surface of the liquid absorbed in knitwear and yarns by capillary attraction and also in the structure of the fiber in the case of hydrophilic polymers. Second, the fluid moves through the structure of a combination of diffusion and capillary movement of liquid. In the case of material produced from hydrophilic fibers , such as cotton or wool , the initial wetting liquid molecules allows for access to the fiber surface and then efficiently move " the solution " to the structure of the polymer while the polymer becomes saturated . The liquid then enters the capillary spaces between fibers and runs or wicks to move away from the structure of the reservoir fluid. Distance traveled depends on the contact angle between the liquid and the polymer, and the physical dimensions of the capillary space. The fluid that enters the solution within the fiber is effectively trapped and prevented from moving away from the source.Of course , hydrophobic polymers prevent the liquid solution enters the fiber and thus prevent capture of moisture. With time fluid has traveled along the capillary cross will evaporate, and then diffused into vazdužni space knitting. If there is a pressure gradient across the air molecules knitting fluid will be transferred to the air space and the knitting. Higher air flow will be determined by the pressure gradient, and thus a higher gear fluid. When you make a comparison between the fabric and knitted kntting made from the same polymer combination / fiber / yarn then capillary wick and the liquid in a polymer solution, of course, be similar. The main difference will be in the flow of air through the fabric and knotted knitting to be more porous and thus the transmission fluid level will be higher.

ComfortComfort knitting is a very complex issue and the complexity of the variables involved. For example, the knitwear that is comfortable in cool dry environment can be uncomfortable to wear in hot humid climates. In order to have a meaningful discussion should state the following:• environmental conditions , including temperature , humidity , wind speed and precipitation ;• the level of activities of ;• function of clothing, such as underwear, outerwear, jackets ( rowboat ) , trim , etc. ;• fitting clothing.The perception of comfort is carried out through a number of physiological interaction of textiles and the wearer:• mechanical interaction between the surface of the skin and fibers and yarns. This includes the roughness or smoothness, as well as pressure, shear and tear.• humidity as the holder of sweating or urination rain in the outer layer.• Temperature condition in the body generates heat through exercise or penetration of heat to the surface from the outside.Against this complex background knitwear offer benefits in three major areas.First,the strength properties of knitwear offer better compliance and preventing the excess of pressure and / or the development of shear between the garment and the body surface. This is especially important for underwear , as well as for active sportswear and swimwear to the extent that the vast majority of these goods are made of knitwear . Second, as already mentioned, knitwear offer substantial advantages over the fabric in terms of isolation, especially when they are protected from the wind.Third, knitwear behave well when there is a need for the transfer of sweat from the skin surface. These features increase the advantage of the natural extension of active sports applications.Conversely, knitwear does not provide good protection from the wind and cold and must be used in such circumstances under knitwear inserted podstavna tkanina.Slično are difficult to effectively waterproof.

Capillary rise of modeling 3D woven structuresMacro-and micro-porosityIt was developed for capillary rise Savka channel model. Porous medium knitwear contains pores that are filled with fluid. Pores can communicate and exchange matter and energy. Hard part is called "matrix" can be deformed, but he must have cohesion (Okarango, 2004).

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The phenomena occurring in porous depend on the geometry of the solid matrix, which may be consolidated or porosity (ε) is characterized by a particular form of average, geometric or static size and usually capillary rise modeling is defined as the ratio of pore volume to total volume available (Bories and Pratt : Techniques de l'Ingenieur (8A 250)):

ε (% )=

V a

V T : (1)where Va - The volume of available pore through which the fluid runoff occurs, VT-total volume of the sample.Braided structures (Figure 1 and 2) is a porous medium that offers several advantages.Physically it is a comfort feature, such as high elasticity, comfort in shape, softer touch and better feel fresh, and more.Porosity is one of the important physical properties, which affects the comfort aspect and use.

Figure 1.Three dimensional elementary Jersey loop shape. Figure 2.Ribbed interlacement 1+1.

Analyzing the knitted structure (Figure 3), we observe two porous scales: macro pores - vacuum between the yarn structure and micro-pores a vacuum between the fibers into yarn.

Figure 3. Side view of Jersey loops (macro and micro-channels), Right geometric design of the unit cell 3D knitwear.

Macro-porosity

In a study (Benltoufa and others., 2007), macro porosity channels is determined as follows:

εmacro=1− πd2 ℓ CW

2 t (2)

where t- is the thickness of the sample, ℓ− the length of the yarn in the loop (mm), d-diameter of yarn, C-number rows of loops, W-series of loops.

Micro-porosityPorosity of yarn is defined as:

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ε micro=1−

V of nsfibers in yarn

V Yarn (3)As pointed Norvick (Suh, 1967), there is a wide range of cross-section yarn in woven structures. So they need some simplification in an attempt to develop a theoretical model geometry. In the modeling we assume [2, 3, 4] that the yarn has a circular cross section and uniform diameter, which in reality it is not.So:

V zarn)

πdzarn2 Lloop

4 (4) where Lloop elementary length of the yarn loops. As can be seen from Figure 3 the diameter of the yarn dyarn = t/2, where t is the thickness of the knitwear.Then:

V zarn=

πt 2 Lloop

16 (5)Also, the volume ns fiber in the yarn cross-section is:

V ns fibers=ns π

d fibers2

4Lloop

(6)Substituting (5) and (6) into (3) yields:

ε micro=1−

4 ns d fiber2

t2 (7)

In fact, capillary progression between the knitting yarn can simulate the flow between two parallel plates distant (capillary length) (Figure 4). While, on the scale of the cross (between fibers) can be analyzed as a flow in the capillary tube radius Rmi (Figure 5).

Figure 4. Capillary progressionbetween yarns (macro channels)

Figure 5. Capillary progressionbetween fibers (micro channels)

Model ordinary Single jersey knitted knitting as porous

The unit cell of a regular Single jersey knitted structure (Figure 6) is a loop, which is created by the abstraction between the yarn loops. The loops are arranged in rows and rows, where you can see the empty space of the unit cell is almost the same cylinder, which limited the scope of yarn loops created. Since there is a uniform distribution of loops that make up the knitting, there is a unique array of circular cylinders in a unit area, while knitting usually can be modeled as a layer with identical cylindrical pores perpendicular to the surface.

Figure 6. Right-ordinary person Single Jersey knitted structure (Dias Monaragala, 2006).

The experimental part

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Distance between series

Directionseries

Direction rows

Gaps in the unit cell modeled in 2D as a circle of radius R

Thickness

For the experimental investigation of absorption capacity, are woven of different patterns of spatial structure similar knitted knitting machines Shima Seiki to finesse 7 [11]. In order to achieve different porosity, capillary radii and angle on surface capillaries was changed to different numbers of spatial yarn between two knitted rows with varying number of space between two consecutive rows traps. Table 1 [11, 3] shows the specification of different knitting polyester spatial structures used in the experimental and theoretical works. It also shows the capillary radiuses, which are calculated by the model and the porosity of the fabric sample weight, thickness and surface area of 50.26 cm2. Capillary radii given in Table 1 are calculated using jednadžine (Delkumburewatte, 2007):

r=√ t⋅1w⋅S−[rows⋅c √(t2+ S

w2 )⋅1/ (1−crimp )] /105⋅T / ρf

170⋅rows⋅c⋅√( t2+ Sw2 )⋅π

,

(8)where t is the thickness of knitting, w is a series of loops per cm, c the number of rows per cm, S is the number of needle space needle between two traps, 'rows' is the number of spatial yarn in one repeat, T is the number of spatial yarn and ρf is fiber density.

Table 1 Specification ofknitting, porosity, capillary radii and its spatial patterns [11], with the diagram shown below [3].

Sample Spatial Thickness(mm)

Weight(gr)

Series percm

Rows per cm

Loopsper cm2

Capillary radius ( m)μ

Porosity

Spatial 21 9 13.20 5.40 5.00 6.67 33.35 60.94 0.960Spatial 22 10 13.35 5.35 4.60 6.67 30.68 55.63 0.960

Spatial 23 6 9.55 4.20 4.62 6.60 30.50 59.09 0.9607Spatial 24 7 10.20 4.69 4.81 6.29 30.30 56.69 0.957

Spatial 25 8 10.40 5.09 4.81 6.29 30.30 53.20 0.953Spatial 26 9 10.15 5.15 4.63 5.93 17.50 51.64 0.952

Spatial 27 10 10.45 5.40 4.44 6.30 28.00 48.14 0.944Spatial 7 12 10.30 6.60 5.00 5.60 28.00 48.86 0.931

Spatial 8 8 11.10 5.42 4.40 6.75 29.70 63.30 0.959Spatial10 6 9.10 4.52 4.40 7.00 30.20 58.12 0.957

Spatial 11 7 10.30 4.95 4.06 7.56 30.70 56.66 0.958

5

0 2 4 6 8 10 12 140

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

Series2Series4Series6Series8Series10Series12Series14Series16

The experimental results

Figure 7 shows the experimental absorption grams per 100 grams of knitting [11], while Figure 8 shows the absorption of water in grams per 50 cm2 [11]. In the case of materials for clothing, it is important to know the capacity of absorption per square unit of area, and percentage. Figure 7 shows that samples knitting with higher porosity have higher total absorption. For example, the pattern SP-21 with a porosity of 0.960 and a sample SP-8 with a porosity of 0.959 higher overall absorption capacity (absorption) around 1200%. Also, knitting patterns less porosity, SP-7 with porosity of 0.931 and SP-27 with a porosity of 0.944, with lower overall absorption capacity (absorption;) of 900%. The total absorption of other knitting patterns have a similar sequence according to their porosity variations as given in Table 1. Figure 7 shows that the samples knitting SP-21, SP-22, SP-26 and SP-8 have a higher absorption rate and consistent from beginning to saturation with respect to other structures in tabeli.To also shows that the rate of absorption between saturation and 400% absorption, similar to most structures. However, knitting patterns with lower capillary radius and high capillary angle (sin φ) on the horizon showed a lower rate of absorption. Figure 8 shows the absorption per unit area of knitting patterns followed a similar pattern in terms of percentage of absorption. However, the total absorption per unit area seems to vary with the thickness of knitting, knitting thicker higher overall absorption per unit area.

Figure 7. The experimental absorption rate spatial twists given in Table 1 as a percentage [11].

Figure 8. Absorption spatial knittig listed in Table 1 (50 grams per cm2) [11].

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Figure 9. Theoretical and experimental absorption selected spatial structure [11].

Figure 9 shows the comparison of theoretical and experimental absorption five chosen space. T and E indicate the theoretical (continuous) and experimental (dots) absorption of selected samples of SP-24, SP-25, SP-26, SP-8 and SP-11th.It shows that the theoretical and experimental total absorption is almost the same with the given structures.When the experimental values are compared with the theoretical rate raise upwards of liquid, the sample is almost the same, although there are some differences. In the initial stages of the theoretical absorption rate is higher than the experimental, because we took the average constant contact angle of 75 ° (cos75 = 0.2588), which is lower than the actual dynamic contact angle. At the beginning of the dynamic contact angle is closer to 90 ° (Heinrich and al. , 2006) and thus provides a closer cos 90 0 Thus , the value of ℓ ( t) jednadžini 2 will be lower until it reaches the dynamic contact angle of 75 °. After that, the dynamic contact angle will be less than 75 ° , which leads to higher values of ℓ ( t) jednadžini 2 So the theoretical absorption rate will be lower than at the start date to the theoretical value of the dynamic contact angle of 75 ° . Similarly, after reaching a dynamic contact angle of 75 ° the actual theoretical absorption rate must be higher than the theoretical value given to excess.Figure 9 shows that the time required for saturation of the theoretical and experimental varies between 6 and 10 minutes for a given structure. The theoretical time required for saturation is greater than the experimental time for the same explanation given as to the rate of absorption after the dynamic contact angle of 75 ° .The models were developed to predict the absorption of knitted spatial structures can be used directly for the planned total absorption in knitted spatial structures made of monofilament yarn texturing . The model can be used to predict the absorption rate and the time required for saturation. However, if the dynamic contact angle is considered in formula, shape , and absorption saturation time can be predicted accurately.

Future TrendsTextile structures can be produced in water in geo-textiles, agro-textiles and clothing materials under different conditions.Special woven structures can be produced as a liquid batteries for medical and technical textiles. Kapilarnni effects and gravity can be used to 'pump' ground water for agricultural purposes in the area, drop by drop, if properly designed.

Literature

[1] Sofien Benltoufa, Ph.D., Faten Fayala, Ph.D., Sassi BenNasrallah, Ph.D. LESTE (Laboratoire d'Etude des Systèmes Thermiques et Energétiques), Monastir, TUNISIA, Capillary Rise in Macro and Micro Pores of Jersey Knitting Structure, Journal of Engineered Fibers and Fabrics 47 http://www.jeffjournal.org Volume 3, Issue 3 – 2008.[2] Vojislav R. Gligorijević. Projektovanje pletenih materijala /. - Leskovac :Tehnološki fakultet, 2010 (Leskovac : V.Gligorijević). - 1 elektronski optički disk (CD-ROM) ; 12 cm.,ISBN 978-86-82367-86-4.[3] Vojislav R. Gligorijevic. Tehnology of Knitting with the Theoretical Experimental and Analysis : #a #comprehensive handbook and practical guide / Vojislav R. - 1st ed. in English. - Leskovac : V. Gligorijević, 2011., ISBN 978-86-914211-3-7.[4] Vojislav R. Gligorijević. Tehnologija pletenja sa teorijskom i eksperimentalnom analizom / -Leskovac:V.Gligorijević,2011.,ISBN 978-86-914211-2.[5] S.C.Amico and C.Lekakou, 2002, axial impregnation of a fibre bundle. Part 2. Theoretical analysis, Polymer Composites, 23(2), pp.264-273, 2002. [6]S.C.Amico and C.Lekakou, 2000, Axial impregnation of a fibre bundle; Part 1-Capillary experiments through woven fabrics, Composites A, 31(12) special issue, pp.1331-1344, 2000. [7] O. Rahli, L. Tadrist, M. Miscevic, R. Santini, J. Fluid Eng. Trans. ASME 119 (1997) 188.

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[8] P.K. Chatterjee, Absorbency, Elsevier Scientific, New York, 1985. [9] Y.K. Kamath, S.B. Hornby, H.-D. Weigmann, and M.F. Wilde, 1994, Wicking of Spin Finishes and Related Liquids into Continuous Filament Yarns, Textile Research Journal 64: 33-40, 1994.[10] S. Benltoufa, F. Fayala, M., Cheikhrouhou and S. Ben Nasrallah; "Porosity Determination of Jersey Structure "Autex Research Journal, N°1, March 2007 (pp 63-69). [11] G. B. DELKUMBUREWATTE, Weft-knitted structures for moisture management,Open University of Sri Lanka, Sri Lanka.

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