INFLUENCE OF TECHNOLOGY PROCESS ON RESPONSIVENESS … · 2020. 12. 5. · nonwoven textiles for the footwear industry – especially for the provision of hygienic properties. The

INFLUENCE OF TECHNOLOGY PROCESS ON RESPONSIVENESS OF FOOTWEAR NONWOVENS

Dunja Šajn Gorjanc1*, Ana Bras1, Boštjan Novak2

1 University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Textiles, Graphic Arts and Design, Ljubljana, Slovenia, Snežniska 5, SI-1000 Ljubljana

2Alpina d. o. o., Strojarska 2, 4226 Žiri, Slovenia*Corresponding author. E-mail: [email protected], tel.: +386 1 2003220

1. Introduction

The footwear industry present currently in the market is faced with a multitude of new materials. The type of the material depends on the price of the product and its quality. Nonwoven textiles which are intended for the use in the footwear industry are predominantly made of chemical fi bres. Recently, the manufactured materials made from recycled material have been on the increase. The properties which are important in strengthening the footwear and foot rests during the wearing are resistance to abrasion, water vapour permeability and water permeability, heat resistance and mechanical characteristics (i.e. viscoelastic deformation and pressure).

In the footwear industry, knitwear, woven and nonwoven textiles are used. Knitwear is very elastic and fl exible, and can often not be coated due to their open structure. Woven fabrics are used to a lesser extent for coating. Nonwoven textiles are

the most commonly used. However, many nonwoven textiles cannot be directly coated due to their rough and uneven surface. Therefore, the coating and lamination techniques are commonly used in the footwear industry. [1, 2]

2. Theoretical Part

In the footwear industry, woven fabrics, knitted fabrics and also nonwoven textiles are used. Knitted fabrics are fl exible and stretchable, and can usually not be directly coated due to their fl exibility and open structure. They are generally coated with a transfer coating to produce coated materials with a soft touch [1]. The knit is formed by bending the thread into a loop and tangling into the loop. We distinguish between different types of knitting. According to the knitting process, we know two basic types of knitting, i.e. warp and weft knitted fabrics. The warp knitted fabric consists of loops from basic threads, connected

Abstract:

Nonwovens represent a part of technical textiles that are used for clothing (“cloth tech”). Nonwovens are also used in the footwear industry mainly for functional purposes, where the aesthetic properties are not of great importance. They are mainly used for support and reinforcement of footwear. All three groups of textiles are used for footwear, i.e. woven fabrics, knitted fabrics and nonwovens that are produced directly from fi bres, yarns or threads mainly from chemical fi bres and in a small proportion from natural fi bres.

Footwear textiles need to have good mechanical properties (at compressive loading), abrasion resistance, permeability properties and heat resistance. These properties are in close connection with the nonwoven structure or composite materials.

The basic intention of the presented research was to analyse the infl uence of the technology process on nonwovens for footwear responsiveness. Analysed footwear nonwovens in the presented research were on one side coated but on the other side consisted of a two-layer laminate. For this purpose, two different technological processes were used (coating and lamination). The results of the presented research showed that laminated samples express higher elastic recovery at compressive loading than coated samples. The treatment does not have an important infl uence on elastic recovery at compressive loading. Laminated samples express higher water permeability and lower absorption of water than coated samples, even after 24 hours of treatment in distilled water and compressive loading. The treatment of specimens in distilled water for 24 hours and compressive load of 789.6 N does not have an important infl uence on elastic recovery at compressive loading, water vapour permeability, air permeability and absorption of analysed samples. Air permeability could not be measured on coated samples.

Keywords:

nonwovens, coated textiles, laminates, mechanical and permeability properties

AUTEX Research Journal, Vol. 20, No 4, December 2020, DOI 10.2478/aut-2019-0053

© 2020 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

in the vertical and horizontal direction. The weft knitted fabric is made up of loops from a single thread, connected in the horizontal direction to a loop type. The loops of a warp knitted fabric are made from many interlaced loops; therefore, it is almost impossible to mate. The weft knitted fabric can be welded in the opposite direction of knitting, while the left-right knitted fabric is welded in the direction of knitting.

Weft knitting is the simplest method of converting yarn into fabrics. The types of weft knitting are plain knit, purl knit, interlock knit and rib knit. If a weft knitted fabric has one side consisting only of face stitches and the opposite side consisting of back stitches, then it is described as a plain knitted fabric. Plain knitted fabrics are produced by using one linear array of needles. If on both sides of a relaxed weft knitted fabric only reverse stitches are visible, then the latter is defined as a purl knitted fabric. Purl fabrics are produced by meshing the stitches in adjacent courses in opposite directions either by using special latch needles with two needle hooks or by transferring the fabric from bed to bed between each knitting action. Interlock knitted structures could be considered as a combination of two rib knitted structures. The reverse stitches of one rib knitted structure are covered by the face stitches of the second rib knitted structure. Thus, only face stitches are visible on both sides of the fabric and it is difficult to detect the reverse stitches even when the fabric is stretched widthwise.

A relaxed weft knitted fabric where only face stitches are visible on both sides is referred to as a rib knitted fabric. It is produced by meshing the stitches in adjacent wales in opposite directions. This is achieved by knitting with two needle systems which are placed opposite to one another. [1, 2]

2.1 Methods of manufacturing nonwoven laminates and coated nonwovens for sports footwear

The laminates are composed of at least two layers of which at least one layer is textile. The finished product or laminate formations depend on the number and type of aggregate layers as well as on the type of the binder.

The types of binders most commonly used in laminated textiles are powder, adhesive, flamed or special binders – adhesives.

Regarding the binding principle of the binder, we distinguish among dry, wet and flame activation of the binder.

2.1.1 Laminating textiles

Critical factors to consider are the lamination method and the choice of the material. The simplest method is the method with calendars.

In recent years, the production of laminated textiles with the so-called “hot-melt” lamination has greatly expanded. [1]

Method with calendars

The materials are brought into the machine in several layers with a binder in the middle (sandwich). The binder may be

powder, a net or a film. Heat passes through the material for the binder to soften and in this way connect individual layers to one another. This can result in thermal damage, e.g. waxing and breaking of layers. [3]

Open lamination system

Before the materials are guided between the laminating rollers, the hot-melt of the polymer, which is located between the materials, is melt due to infrared rays [3].

The melt of the polymer is in the form of a film or a net. Due to the polymeric coating on the surface of the material, the upper cylinder must be coated with Teflon so it does not collapse. The bottom roller can be coated with silicone. [3]

Wide laminated closed lamination system

A “hot-melt” binder is applied through a slit nozzle over the entire width of the first substrate. In the area between the laminating and guide roller, another substrate is supplied, which joins under the pressure of the two cylinders into the laminate [1, 3].

The analysed samples were laminated using hot-melt lamination with a calendar.

2.1.2 Coating of textiles

With various coating processes for hardened textiles, these become impervious to liquids, waterproof, flame retardant etc.

For the coating of textiles with dispersions, pastes, foams and plastisols, squeegees are used, which are of various shapes and in different layouts [3].

For knitted fabrics that are more open and elastic in comparison with woven fabrics, transfer coating is used.

These materials cannot be coated with direct printing as they would deform or wiggle under the loading of the material prior to coating (that means for handling or flattening the material prior to coating).

Transfer coating

In transfer coating, the polymer is first sprayed onto the transfer paper to form a film, and only then, the film is imprinted onto the material. The polymer does not come into contact with the material until it is in the form of a film. The upper layer is first applied to the transfer paper with a squeegee and then dried in a dryer. The base layer is applied to the second layer above the first layer and then, the material is laid over the base layer. The compression roller combines all three layers together. The transfer paper then goes together with the coating and the material into the dryer where the two layers are dried and combined. The base layer is glued to the material. The coated material is then wound onto the coil at the exit of the dryer.

Transfer coating is more expensive than direct coating due to the cost of transfer paper. [1]


http://www.autexrj.com/ 540

Coating with rotary printing roller

A polymer mixture is located inside a perforated rotary printing roller, which rotates and applies the polymer to the surface of the material.

The advantage of this method is that the mixture is placed onto the surface of the material, causing no deformation. This means that non-woven textiles and very light elastic materials can be coated with this process. In practice, only simple aquatic compounds are used for this method.

This method is also used for point coating with a binder, adhesive and hot-melt melt.

The analysed samples were coated using a rotary printing roller. [1, 3]

2.2 Research review in the field of nonwoven textiles for sports footwear

So far, research has been focused on the so-called eco-needle bonded nonwovens used for the footwear industry [4].

Similarly, articles also discuss the use of bamboo fibres for nonwoven textiles for the footwear industry – especially for the provision of hygienic properties. The natural bamboo fibre is known to have a natural antibacterial effect [5].

The research also focuses on 3D nonwoven structures that are constructed after the so-called strutto procedure, where, according to the carding process, the fibres in nonwovens are diverted from the horizontal to the vertical direction by vertical lapping (with a vibrating or rotating roller) [6].

Furthermore, some recent research has been devoted to the production of artificial leather from needling or general mechanically bonded nonwovens, e.g. with water jets (spunlace nonwovens) [7].

Current research also addresses the compression load of nonwovens in the dry and wet state of the footwear industry [8], as well as the thermal and permeability properties of such nonwovens [9], and the influence of technological parameters (in mechanical bonding) on the structural and related mechanical and physical properties of nonwovens for the footwear industry [10].

In the footwear industry, it is very important that the products prevent the user from developing an unpleasant smell in order to avoid the growth of microorganisms (fungi), maintain the dryness and influence the user’s thermal comfort [11].

Previous research shows that, due to the ecological aspect, biodegradability, recycling [12], low cost and product quality [13] are of the essence. Therefore, environmental awareness has prompted many industries – especially in high-income countries – to consider more sustainable modes of operation [14].

Environmentally friendly biocomposites have been developed from biodegradable reinforcing polymers [15].

Research has confirmed that textile waste material can be safely used to strengthen the structure of fibres in the production [16].

Moreover, it was explored that the fibres for clothing and footwear industry are robust, have high tensile strength, non-flammable properties, water repellence, air permeability [17] and thermal conductivity which is important as well [18].

The mechanical properties of fibres from chemical fibres (bicomponent fibres) are in addition to needle bonding also influenced by the conditions of heat treatment, which affects the change in the fibre density and consequently their specific surfaces [18, 19].

3. Experimental Part

3.1 Materials

The materials used in this research were made of laminated and coated nonwovens, and are used for sports shoes.

The analysed coated and laminated nonwoven textiles used in the research are intended for the footwear industry. They were produced by the dry-laid (carded) web formation process and were mechanically bonded (by needling).

The nonwovens from PES fibres were on the front side coated with a hot-melt PES coating (cf. Table 1). The coating was conducted with a rotary printing roller. The coated PES nonwoven samples are labelled P1 to P5 and their mass ranges from 800 to 1785 g/m2.

On the other side, the laminated nonwoven samples consisted of PES (back) fibres, and 2D and 3D warp knitted fabric from PA and PES fibres (cf. Tables 1 and 2). A hot-melt lamination with a calendar was performed for lamination. The laminated nonwoven samples are labelled L1 to L5 and their mass ranges from 580 to 800 g/m2.

The coated and laminated nonwoven samples were measured in untreated and the so-called treated conditions, where they were immersed for 24 hours in distilled water, dried and loaded for 24 hours with the load of 789.6 N. This corresponds to the weight of 80 kg, representing the average mass of a person.

Table 1 shows the chemical composition and structure of analysed samples.

3.1.1 Structural properties of analysed samples

The structural characteristics of analysed samples are given in Tables 2 and 3, i.e. mass, thickness, chemical composition and diameter of fibres. The results are given for untreated samples and for the samples after 24 hours of immersion in distilled water and loading at 789.6 N, i.e. the so-called “treated samples”.



Tables 4 and 5 show the SEM analysis of analysed samples at 30×, 1000× and 300× magnification.

3.2 Methods

3.2.1 Elastic recovery at compression loading

Since the methods for elastic recovery at compression loading are performed only on the whole footwear according to the ASTM F1976 - 13 standard [20], the measurements were conducted as follows:

• Diameter of the upper clamp: 6 cm,

• Load: 930 N,

• Surface area: 10 × 10 cm,

• Number of measurements: ten samples of two parallels,

• Number of cycles: 10 cycles to 930 N force, at the last cycle, the sample was loaded for 10 min, then the sample was relieved for 3 minutes, after which we also performed the control cycle.

3.2.2 Water vapour permeability

Water vapour permeability analysis was performed according to the ASTM standard: E 96/E96M [21].

Table 1. Presentation of analysed samples

SamplesChemical

composition Structure

Front Back Front Back

L1 PA 6,6 PES 2D warp knitted fabric Nonwoven

L2 PA PES 2D warp knitted fabric Nonwoven

L3 PES PES 3D warp knitted fabric Nonwoven

L4 PA PES 2D warp knitted fabric Nonwoven

L5 PA 6,6 PES 2D warp knitted fabric Nonwoven

P1 PES PES Hot- melt PES coating Nonwoven

P2 PES PES Hot-melt PES coating Nonwoven




Table 2. Chemical composition, mass and thickness of untreated and treated samples

SamplesChemical composition

Mass,M [g/m2]

Thickness,h [mm]

Front Back Untreated Treated Untreated Treated

L1 PA 6,6 PES 581.5 604.1 1.625 1.839

L2 PA PES 687.9 619.9 1.647 1.600

L3 PES PES 389.1 369.5 2.267 2.425

L4 PA PES 690.9 719.8 1.874 1.901

L5 PA 6,6 PES 800.7 824.9 3.013 2.923

P1 PES PES 1785.4 1873.7 2.537 2.511

P2 PES PES 1679.5 1855.9 2.722 2.751

P3 PES PES 1729.4 1756.0 2.642 2.659

P4 PES PES 1709.7 1742.7 2.922 2.786

P5 PES PES 1577.6 1801.1 2.968 3.006



7 ml of distilled water was poured into a water cup, for the water to cover the bottom of the container. The empty space represents certain resistance to the water vapour fl ow, which is also required in order to prevent the water from touching the test piece when it moves.

The temperature in the chamber was 23 °C and the relative humidity was 55%. The test specimen was attached to the water cup and covered with a cover with an aperture of 3 cm in diameter. The water cup was weighed together with the sample and placed into the chamber. After 24 hours, we took the dish out of the chamber, weighed it again and recorded the mass. The water vapour permeability was calculated with equation (1).

(1)Where: m = the difference in the mass of the water cup with water and sample immediately and after 24 hours (g), S = the surface of the lid open (m2) and t = time (h).

3.2.3 Air permeability

Air permeability was measured according to the ISO 9237 standard [22] at the pressure 100 Pa, the test surface was 100 cm2 and the air volume was 10 l/min. We prepared ten samples, for each sample the fi ve parallels were made.

3.2.4 Static absorption test

The absorption test method was performed according to AATCC 21 [23].

The samples were weighed and immersed into a beaker with distilled water for 10 minutes. The water height in the cup was 10 cm. After 10 minutes, the samples were removed, purged with an absorbent paper and loaded with the weight of 10 kg (metal roller). The tested sample was again weighed and fi nally, the percentage of absorbed water in the sample after the loading was calculated. The water absorption was calculated using equation (2).

(2)

Where: A = absorption (%), mwet = mass of wet sample (g), mdry

= mass of dry sample (g).

3.2.5 Porosity

In their structure, textiles have empty places called pores. Similarly, nonwoven textiles contain pores. These may be larger or smaller, and are formed depending on the way the nonwoven textile is bonded, i.e. mechanically, thermally or chemically. The degree of openness depends on the surface.

Description of device for measuring porosity

The apparatus consists of a compressor that creates pressure of 8 bar, a reducing valve which reduces the pressure to 2.5 bar and an auxiliary tank to which the rotameter is connected with a measuring range of up to 833 cm3/s and a U-manometer. A pressure regulator valve is present between the auxiliary tank and the rotameter. Through the rotameter, the moving air comes into the measuring element with a clamped pattern. The measuring head allows the clamping of samples of diameter from 1.5 to 10 cm. The pressure-fl ow measurement should be carried out as accurately as possible on the air permeability measuring apparatus. We made two measurements. First, we made the measurements for the dry sample and then for the wet. Distilled water was used as the wetting agent for textiles. The dry and wet sample was introduced into the measuring head and the pressure/air fl ow were measured at predetermined fl ow rates.

In wet samples, we paid particular attention to the pressure at which the fi rst bubble of air appeared on the sample surface as well as to the fl ow along it. We were careful that the pressure increased similarly in the dry and wet sample measurements. [24, 25]

3.3 Statistical analysis

The purpose of the statistical analysis was to determine the coincidence of differences between the analysed samples produced using the laminated and coated process on the one hand, and between the untreated and treated samples,

Table 3. Fibre diameter of samples

Samples

Diameter of fi bres[µm]

Untreated Treated

Front (warp

knitted)

Back(nonwoven)

Front (warp

knitted)

Back(nonwoven)

L1 24.3 21.3 24.1 21.1

L2 26.1 21.4 25.9 20.9

L3 13.8 9.5 14.1 9.4

L4 25.9 20.5 26.2 20.1

L5 25.9 38.5 25.6 37.8

P1 / 19.3 / 20.1

P2 / 19 / 19.8

P3 / 18.8 / 17.8

P4 / 19.3 / 18.9

P5 / 16.9 / 17.1



i.e. those that were immersed in distilled water for 24 hours and loaded with the force of 789.6 N. For this purpose, we selected a one-way and two-way ANOVA analysis. In a one-way ANOVA, we study only one property or an indicator of the property (in our case that was the treatment), and in a two-way or multiple analysis, this property or indicator of properties is observed through several factors. With the F-distribution, we determine whether the scattering between and within groups is random or statistically significant. [26]

We studied the effects of the following factors:

• impact of the technology process (lamination and coating of nonwovens) and

• treatment of samples for 24 hours in distilled water at the load of 789.6 N.

Table 4. SEM analysis of nonwoven laminates

Samples Front Back

30× magnification 1000× magnification 300× magnification

L1

L2

L3

L4

L5



4. Results with Discussion

4.1 Elastic recovery at compressive loading

The results of elastic recovery at compressive loading are shown in Table 7.

The results of the two-way ANOVA are collected in Table 6, the F-test determining the importance of the influence of individual factors on the analysed property (cf. Table 6).

Table 5. SEM analysis of coated nonwoven samples

SamplesFront Back

30× magnification 700× magnification 1000× magnification

P1

P2

P3

P4

P5



The measurements showed that 24 hours of treating samples in distilled water at the load of 789.6 N does not affect elastic recovery, since the differences among all analysed samples were minimal.

4.2 Water vapour permeability

Table 8 shows the results of water vapour permeability.

The research results of water vapour permeability show that the water vapour permeability of coated samples (P1–5) ranged from 18.23 g/m2h and 23.34 g/m2h, whereby the water vapour permeability of laminated samples (L1–5) was expectedly higher and ranged from 61.57 g/m2h to 70.49 g/m2h. The highest water permeability characterised the laminated sample L3 (389.1 g/m2h) and the diameter of fibres – the fibres of nonwoven part of the sample (9.5 μm) and 3D warp knitted fabric fibres part in the analysed textile laminate (13.8 μm). The lowest water vapour permeability was expressed at sample P3 (18.23 g/m2h), which was coated and had at the same time also a very high mass (1729.4 g/m2). It was followed by sample P1, which had water vapour permeability of 18.86 g/m2h and mass 1785.4 g/m2. The analysis of results of water vapour permeability also shows that the 24 hour treatment of samples in distilled water at the load of 789.6 N does not affect water vapour permeability, since the differences among all analysed samples were minimal.

4.3 Air permeability

The results of air permeability are shown in Table 9.

The highest air permeability was seen at sample L1 (229.8 l/min), followed by sample L2 (222.5 l/min). Samples L1 (18.5%) and L2 (8.8%) had a higher proportion of surface openness compared to other samples. Sample L3 had the lowest air

From the results of elastic recovery at compressive loading, it can be seen that the elastic recovery of laminated samples ranged from 42.65% to 64.87%. For coated samples, the elastic recovery was on average lower and ranged from 51.13% to 62.88%. Sample L1 had the highest elastic recovery among laminated samples, while the lowest was observed at sample L5. Sample L1 also had the highest value of elastic recovery after 24 hours of relaxation (98.30%), whereas sample L3 (91.62%) had the lowest value. The highest value of elastic recovery among coated samples characterised sample P1 (62.88%) and the lowest sample P5 (51.12%).

All coated samples had a very high elastic recovery value after 24 hours of relaxation, since the differences between the measurements were minimal. Sample P4 had the highest value (99.93%), while the lowest was measured at sample P5 (97.32%).

Table 6. Two-way ANOVA

Source of

variation

Degrees of

freedomSum of squares Mean

square F-test

Factor 1 nMS = i – 1 AMS = jMSi – ) 2 = FMS =

Factor 2 nVS = j – 1 AVS = jVSj – ) 2 = FVS =

Error

no = (i – 1) (j – 1) = N – i –

j + 1

AO = (xMSiVSj – MSi – VSj – )

So2 =

N = i · j

Total ns = N – 1 AS = (xMSiVSj – ) s2 =

Table 7. Results of elastic recovery at compressive loading of untreated and treated samples

Samples

Elastic recovery at compressive loading,Eel [%]

Elastic recovery after 24 hours of relaxation,Eel [%]

Untreated Treated Untreated Treated

L1 64.87 51.80 98.30 96.81

L2 59.34 56.87 98.10 99.94

L3 64.01 63.39 91.62 99.88

L4 61.70 60.07 97.86 95.30

L5 42.65 40.73 97.60 96.97

P1 62.88 68.10 99.77 97.72

P2 59.66 58.31 99.85 99.36

P3 53.84 49.10 98.77 97.02

P4 53.08 64.80 99.93 97.77

P5 51.13 68.22 97.32 97.02



permeability (88.54 l/min), despite the fact that it had the lowest mass (389.1 g/ m2) and the smallest fibre diameter for nonwoven (9.5 mm) and 3D warp knitted fabric (13.8 mm). It also had low surface openness, which was 5.1%, and the smallest pore diameter, ranging from 17 to 90 μm.

The results of the air permeability analysis show that the treated samples (after 24 hours of treatment in distilled water and loading) have higher air permeability values, the reason being a large number of pores after 24 hours of treatment in distilled water and loading and, consequently, greater surface openness.

Air permeability of coated samples could not be measured.

4.4 Static absorption test

Table 10 shows the results of the static absorption test.

Table 10. Results of static absorption test

Samples

Absorption of water,A [%]

Untreated Treated

L1 6.93 6.87

L2 5.93 7.97

L3 80.00 117.27

L4 7.51 7.67

L5 6.65 10.93

P1 41.75 44.91

P2 41.44 40.75

P3 42.64 45.43

P4 45.06 54.01

P5 44.55 49.88

Absorption depends on the structure of the material and its chemical composition. The results show that among laminates, the highest water absorption of both treated and untreated sample L3 resulted from the highest number of pores, i.e. 11952 pores for the untreated sample L3 and 6335 pores for the treated sample. Other analysed laminated samples (L1–L5) showed a similar number of pores (100–300). Thus, the values of absorption were similar and ranged from 5.93% to 7.51%.

Coated samples had higher absorption values compared to laminates. The reason was the water-impermeable polymeric coating and consequently a smaller amount of water being caught when loading the metal roller, which remains in the samples during static absorption analysis. Values differed very little from each other, both in untreated samples and in treated samples (after 24-hour treatment in distilled water and loading). There were no major differences between the absorption values for coated samples, since the absorption values ranged from 41.44% to 45%.

4.5 Porosity

Table 11 shows the results of measuring porosity on the front side, while Table 12 shows the results of the proportion of a medium surface openness, and the number of pores of the untreated samples and the treated samples after 24 hours of treatment in distilled water and loading.

Table 8. Results of water vapour permeability of untreated and treated samples

Samples Water vapour permeabilityWVT [g/m2h]

Untreated Treated

L1 61.57 65.62

L2 61.99 62.23

L3 70.49 75.55

L4 64.98 62.99

L5 62.66 61.98

P1 18.86 19.33

P2 20.18 21.25

P3 18.23 17.15

P4 20.11 19.89

P5 23.34 24.68

Table 9. Results of air permeability before and after 24-hour treatment

SamplesAir permeability

Q [l/min]

Untreated Treated

L1 229.8 238.5

L2 222.46 286.0

L3 88.54 155.1

L4 204.94 210.4

L5 145.30 150.8

P1 / /

P2 / /

P3 / /

P4 / /

P5 / /



Sample L3, which consisted of 3D warp knitted fabric and nonwoven textile, had the largest number of pores, which at the same time had the smallest diameter (17–90 mm). Sample L3 also had the highest water absorption. Moreover, water vapour permeability and air permeability were the highest at sample L3. The fibre diameter at sample L3 was the lowest among the analysed materials (front 13.8 μm and back 9.53 μm). The largest pore diameter was measured at samples L2 (1335 μm) and L5 (1130 μm). For all observed samples, the highest openness value was shown at sample L1 (18.58%), while for other analysed samples, the surface opening ranged between 3 and 10% in untreated and between 3 and 25% in treated samples. After 24 hours of treatment in distilled water and sample loading, for all samples, except for samples L2 and L3, the proportion of the medium open surface increased.

4.6 Statistical analysis results

The results of the two-way ANOVA are shown in Tables 13, 14, 15 and 16, while the results of the one-way ANOVA are shown in Tables 17 and 18.

The results of the statistical analysis of the influence of the technology process and sample treatment on elastic recovery at compressive loading showed that both analysed factors did not have a statistically significant effect on elastic recovery at compression loading.

The results of the statistical analysis of the influence of the technology process and sample treatment on elastic recovery after 24 hours of relaxation showed that both analysed factors did not have a statistically significant effect on elastic recovery after 24 hours of relaxation.

The results of the statistical analysis of the influence of sample treatment on the surface openness showed that the treatment did not have a statistically significant effect on the surface openness of analysed samples.

The results of the statistical analysis of the influence of the technology process and sample treatment on the absorption of water showed that the technology process had a statistically significant influence on the absorption of water, while the treatment of samples had no statistically significant effect.

Table 11. Measured porosity values

Samples

Porosity

Maximal diameter of pores,Dmax [µm]

Minimal diameter of pores,DRmin [µm]


L1 184 277 23 19

L2 1335 489 19 22

L3 90 71 17 17

L4 918 734 24 20

L5 1130 277 22 17

Table 12. Results of medium open surface and number of pores of treated and untreated samples

Sample

Porosity

Proportion of medium open surface (%) Number of pores


L1 18.57 88.16 373 1837

L2 9.81 3.47 307 655

L3 5.19 4.95 11952 6335

L4 3.94 24.74 154 570

L5 6.63 19.82 164 1433



The results of the statistical analysis of the influence of the technology process and sample treatment on the water vapour

permeability of samples showed that the technology process had a statistically significant influence on the water vapour

Table 13. Two-way ANOVA results for influence of technology process and sample treatment on elastic recovery at compression loading

Source of variation

Degrees of freedom

Sum of squares Mean square

F-test Validity of hypothesis H0

and H 1Fcal Ftab

Technology process nMS = 9 AMS = 819.22 = 91.02 FMS = 2.49 3.18 Fcal < Ftab

Valid H0

Treatment nVS = 1 AVS = 3.39 = 3.39 FVS = 0.093 5.12 Fcal < FtabValid H0

Error no = 9 AO = 328.92 So2 = 36.57

Total ns = 19 AS = 1151.53

Table 14. Table of two-way ANOVA for influence of technology process and sample treatment on elastic recovery after 24 hours of relaxation

Source of variation

Degrees of freedom



and H 1Fcal Ftab

Technology process nMS = 9 AMS = 26.28 = 2.92 FMS = 0.56611 3.18 Fcal < Ftab

Valid H0

Treatment nVS = 1 AVS = 0.088 = 0.088 FVS = 0.017143 5.12 Fcal < FtabValid H0

Error no = 9 AO = 46.43 So2 = 5.15

Total ns = 19 AS = 72.81

Table 15. Table of one-way ANOVA for influence of surface openness

Source of variation

Degrees of freedom



and H 1Fcal Ftab

Between groups nMS = 1 AMS = 940.43 = 940.46 1.51 5.32 Fcal < Ftab

Valid H0

Within groups nVS = 8 AVS = 4967.42 = 620.94

Total 9 AS = 5907.85

Table 16. Table of two-way ANOVA for influence of technology process and sample treatment on water absorption

Source of variation

Degrees of freedom



and H1Fcal Ftab

Technology process nMS = 9 AMS = 15222.16 = 1691.35 FMS = 26.74 3.18 Fcal > Ftab

Valid H1

Treatment nVS = 1 AVS = 199.90 =199.90 FVS = 3.16 5.12 Fcal < FtabValid H0

Error no = 9 AO = 569.26 So2 = 63.25

Total ns = 19 AS = 15991.32



permeability values of samples, whereas the processing of samples had no statistically significant effect.

The results of the statistical analysis of the influence of sample treatment on air permeability showed that sample treatment did not have a statistically significant effect.

5. Conclusions

In the presented research, we compared laminated and coated nonwovens used for sports footwear. We treated them in the so-called untreated condition immediately after the production and then immersed them for 24 hours in distilled water, dried them and loaded then for 24 hours at 789.6 N.

Based on the research, it can be concluded that the untreated laminated samples have on average a higher value of elastic recovery at compression loading and after 24 hours of relaxation compared to coated samples.

The treatment of samples in distilled water at the load of 789.6 N for 24 hours did not affect the values of elastic recovery at compression loading, as the differences between all samples were minimal. All samples also exhibited a very high value of elastic recovery after 24 hours of relaxation (over 95%).

The results of the water vapour permeability analysis led to the conclusion that the laminated samples have by about 3 times higher values than the coated samples. The lower values of

water vapour permeability of coated samples were mainly a consequence of the polymeric coating.

The treated laminated samples had higher air permeability values than the untreated laminated samples. This resulted from a higher number of pores (except for sample L3) after 24 hours of treatment in distilled water and loading, and consequently greater openness of the surface. Air permeability of coated samples could not be measured.

Based on the absorption results, it is evident that the coated samples had by approximately 8 times higher values than the laminated samples. An exception was the laminated sample L3, both untreated and treated, which had the highest absorption values. The reason was in its 3D structure and the largest number of micropores.

The absorption values changed minimally after 24 hours of treatment in distilled water and loading.

The results of the statistical analysis of the influence of the technology process showed that the latter has a significant influence on the absorption of water and water vapour permeability, while it interestingly has no statistically significant influence on elastic recovery at compression loading.

The statistical analysis also showed that the treatment of samples has no statistically significant influence on the measured values.

Table 17. Table of two-way ANOVA for influence of technology process and sample treatment on water vapour permeability

Source of variation

Degrees of freedom



and H1Fcal Ftab

Technology process nMS = 9 AMS = 10202.54 = 1133.61 FMS = 463.33 3.18 Fcal > Ftab

Valid H1

Treatment nVS = 1 AVS = 3.41 = 3.41 FVS = 1.39 5.12 Fcal< FtabValid H0

Error no = 9 AO = 22.02 So2 = 2.45

Total ns = 19 AS = 10227.97

Table 18. Table of one-way ANOVA for influence of sample treatment on air permeability

Source of variation

Degrees of freedom


F-testValidity of hypothesis H0

and H1Fcal

Ftab

Between groups nMS = 1 AMS =

2242.81 = 2242.81 0.65 5.32 Fcal < FtabValid H0

Within groups nVS = 8 AVS =

27547.99 = 3443.50

Total ns = 9 AS = 29790.84



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INFLUENCE OF TECHNOLOGY PROCESS ON RESPONSIVENESS … · 2020. 12. 5. · nonwoven textiles for the footwear industry – especially for the provision of hygienic properties. The