Analysis of the Drapeability and Bending Rigidity of Clothing Packages—A Preliminary Study

Abstract

This paper concerns the study of the multidirectional drape and bending rigidity of clothing packages combined with three types of adhesive inserts. The aim of this research was to investigate the effect of introducing seams of differentiated complexity to clothing packages consisting of cotton fabric and adhesive inserts. The adhesive inserts were differentiated according to their mass per square meter. Three kinds of seams differing by the number of bent and sewn layers were introduced into packages, and two techniques of bonding, differentiated by the sequence of operations, were applied. The results of the influence of bonding technique on the bending rigidity and multidirectional drape for packages with seams and those without them are discussed. All of the tests carried out were aimed at answering the question of how seam introduction and its complexity (the number of sewn layers) influence the bending rigidity and drapeability of clothing packages in order to facilitate clothing technologists in the proper selection of appropriate adhesive inserts for the engineered design of clothing products.

1. Introduction

The textile industry has been undergoing a transformation for several years, adapting to the legislation introduced by the European Union concerning ecological business and production within the frame of the circular economy [1]. Despite the reduction in waste generated during production and the change from conventional techniques to modern ones, the process of bonding garments with adhesive inserts is still indispensable in the practices of the garment industry.

Adhesive insert manufacturers are constantly improving their product lines by using smaller amounts of virgin raw material and using recycled raw materials for production. Changes are also taking place in the use of technology to produce basic materials and adhesive inserts (thermoplastics) and how they are combined. Any modifications in the selection of alternative raw materials and the techniques for manufacturing adhesive inserts should meet relevant criteria during their production. The features required of garment products after the application of adhesive inserts are as follows:

• Strengthening the material, where there is a danger of stretching.
• Improving fabric hand.
• Increasing the durability of the shapes of individual parts of a garment or achieving a certain degree of garment relaxation [2].

The properties of adhesive inserts depend on the properties of basic materials, the type of thermoplastic agent, the geometric distribution, and the shape of glue points. The thermoplastic agent should be inexpensive, suitable for application and materials, and provide good bonds. The properties that are mainly studied in this paper are as follows: the bending rigidity and drape. The material fabric’s bending rigidity influences the comfort of the clothing wearer. The bending rigidity of cotton and cotton/PES fabrics versus their drapeability was examined by Frydrych and Matusiak [3].

Additionally, the bending rigidity influences a garment’s appearance [4] and ability to make folds [5]. However, rigidity is also an important factor influencing fabric hand [6].

In 1930, fabric bending behavior was studied very precisely by Peirce [7]. Models, systems, and methods of measuring bending rigidity have been described by Syerko and others [8], Sadeghi and others [9], and Dziworska [10].

Fabric behavior during bending is nonlinear and divided into two components: frictional resistance and bending rigidity (Grosberg et al. [11] and Kedia [12]). Sadeghi, Jeddi & Najar [9] studied the bending rigidity of woven fabric with different twill weaves (1/2, 1/3, 1/4, and 1/5) and plain structures using an energy method and higher values of bending rigidity for the plain weaves because of very close yarn intersections.

Matusiak [4] investigated the influence of the linear density of weft yarns for nine variants of seersucker fabrics. She measured their bending rigidity using a cantilever tester and an MOO3F digital pneumatic tester. The influence of various sewing conditions on the bending properties of the seams was studied by Suda & Nagasaka [13].

The drape is a unique property that allows a fabric to be bent in more than one direction when two-dimensional fabrics are converted into a three-dimensional garment form. Hu and Chung [14] present a fundamental drape analysis of seamed (radial and circular seams) fabrics using Cusick’s drape meter for plain and twill fabrics with various fiber contents of cotton, linen, silk, wool, and polyester.

Kendra, Frydrych, and Sybilska [15,16] studied the influence of different seams on fabric drape. The authors examined the behavior of different fabrics under their own gravity without a seam or with a seam in the warp, weft, and diagonal directions according to PN-73/P-04736. Seams were applied according to PN-83/P-84501. Based on the obtained results, the influence of raw material, weave, and seam directions was discussed.

Jevsnik and Zunic-Lojen [17] also analyzed drape using a Cusick drape meter with a video camera and drape analyzer and found that the number of folds and the drape coefficient for the samples with seams were greater or, in some cases, equal to those for samples without seams. The distribution and form of folds were also changed.

Nachiappan, Gnanavel, and Ananthakrishnan [18] studied the drape of ten fabrics and analyzed three types of seams and three stitch densities. The drape coefficient of seamed samples was different from that of the control sample (without seams).

The influence of seam introduction in the warp, weft, and bias directions was also examined by Adamiec and Frydrych [19]. Non-unified trends were observed for the results of fabric drape for the samples with seams and those without seams; the behavior of fabrics with seams was different and dependent on the kind of seam and its direction. So far, we have not found information about similar measurements for fabrics bonded with adhesive inserts.

Kim & Takatera studied the shear rigidity of laminated fabrics with different weave densities and adhesive inserts. It was observed that the value of shear rigidity of the adhesive inserts and the bonded fabric increases with the increase in the mass per square meter [20].

The purpose of the presented study was to compare the mechanical parameters, like the bending rigidity and drapeability of garment packages (the basic material plus adhesive inserts) with and without seams. As can be observed, based on the literature, such measurements with seams are not so common, but they are important for clothing technologists, who should be able to predict the behavior of fabrics with adhesive inserts. In the presented research, three adhesive inserts were bonded with the use of two sequences of operation (two techniques) and three selected seams. Two techniques were investigated because, sometimes, unexpected drapeability of clothing packages is observed if they are too thick. Changing the operation sequence can solve this issue. In the study, basic tests on fabric were carried out, and the parameters of clothing packages were determined. The analogous experiment for wool fabrics with adhesive inserts, but without seams, was described in the authors’ previous paper [21]. In this paper, we would like to answer the question of how seam introduction and its complexity (the number of sewn layers) influence the bending rigidity and drapeability of the clothing package to be able to predict its behavior in the produced garment.

2. Materials and Methods

2.1. Basic Materials

A cotton fabric of 0.47 ± 0.005 mm thickness and a mass per square meter of 113.06 ± 2.36, as well as three non-woven recycled polyester adhesive inserts, were used for this study. The metrologicalparameters of the basic cotton fabric are shown in

Table 1. Metrological parameters of the cotton fabric.

Breaking Force [N]	Strain at Break [%]	Number of Threads per 1 dm
Warp 296.80 ± 18.19	14.45 ± 0.65	217.2 ± 2.6
Weft 210.80 ± 26.24	20.73 ± 19.16	132.2 ± 16.2

.

Three adhesive inserts made of recycled polyester, produced using non-woven techniques with random fiber orientations, were used for this study. The raw material used in the adhesive inserts was 100% recycled polyester, while the adhesive points were made of polyamide. The inserts (successively named CE 1016, CE 1026, and CE1036) varied in their mass per square meter, but parameters such as the type of fabric raw material, the type of adhesive mean, the number of adhesive points (37 distributed randomly), and the method of applying the adhesive mean were the same, according to the producer. For a better description and to be sure that the parameters given by the manufacturer were correct, parameters such as the mass per square meter, thickness, breaking force, and strain at break of the adhesive inserts were examined. The results are shown in

Table 2. Metrological parameters of the adhesive inserts.

Measured Parameter	CE 1016	CE 1026	CE 1036
Mass per square meter [g/m2]	27.07 ± 0.36	29.81 ± 1.11	40.05 ± 0.95
Thickness [mm]	0.25 ± 0.006	0.28 ± 0.009	0.34 ± 0.006
Breaking force [N]	15.53 ± 1.95	3.19 ± 0.09	3.49 ± 0.06
Strain at break [%]	8.93 ± 1.29	31.83 ± 0.94	26.87 ± 2.89

.

The results of breaking force and strain at break suggest that the adhesive insert of sample CE 1016 was produced from a different raw material than the rest of the adhesive inserts.

2.2. Sample Preparation

Fabric samples without adhesive inserts and garment packages with three adhesive inserts were prepared for measurement. Three seams, which are the most commonly used in the apparel industry according to PN-83/P-84501, ref. [22] were selected for testing. They differ mainly by the number of bent and sewn-together layers, highlighted further by the seam complexity. They are presented in Figure 1, Figure 2 and Figure 3.

The Method of Preparing Clothing Packages with and Without Seams

The samples were prepared with and without adhesive inserts. The package samples were prepared in two ways, differing by the sequences of undergluing and sewing operations. Clothing technologists sometimes face disadvantages if they are sewing very complex seams (consisting of many layers). There are two kinds of disadvantages—difficulties during the sewing process and worsening of the garment’s appearance. Therefore, the presented experiment is important in deepening the knowledge of technologists, who tend to improve garments’ appearance.

The figures below illustrate how the clothing packages with seams were prepared for the experiment on the example of seam 1.01.01.

• Sequence of undergluing → sewing

Initially, all of the necessary fabric elements were bonded with the adhesive insert and then sewn, forming the required seam. Figure 4 graphically shows the process of preparing the package sample in the sequence of undergluing → sewing.

• Sequence of sewing → undergluing

In order to have a garment package prepared in the order of sewing → undergluing, it was first necessary to connect all of the fabric elements using the appropriate number of seams and to then combine the previously made samples using the seams with an appropriate adhesive insert. Figure 5 illustrates the process of creating a garment package with a seam in the order of sewing → undergluing.

A similar procedure was applied for the rest of the seams. For sewing, an industrial sewing machine SIRUBA DL-7200 (Siruba, Taiwan) was used, which sews with stitch class 301 according to PN 83/P-84502 (Ariadna, Lodz, Poland). The sewing thread used was TALIA 120 (Ariadna, Lodz, Poland), i.e., a cut polyester sewing thread produced by Ariadna, using a GROZ-BECKERT DB X 1 90/14 (Albstadt, Baden-Württemberg, Germany) sewing needle, and an average stitch pitch of 3 mm was used. The tension was set for this material so that the bottom and top threads formed proper interlacing.

The bonding parameters were as follows: temperature T = 130 °C, time t = 14 s, and pressure = 3 bars.

2.3. Basic Parameters of Clothing Packages

The clothing packages were prepared according to the techniques described in the previous subchapter; the clothing packages underwent metrological analysis. The metrological parameters of the clothing packages prepared using the two techniques are shown in

Table 3. Metrological parameters of clothing packages.

Measured Parameter	CE 1016	CE 1026	CE 1036
Mass per square meter [g/m2]	138.40 ± 1.82	143.72 ± 2.18	154.56 ± 0.89
Thickness [mm]	0.61 ± 0.030	0.66 ± 0.011	0.70 ± 0.008
Breaking force [N]	323.60 ± 45.16	347.10 ± 20.94	377.00 ± 13.09
Strain at break [%]	13.57 ± 1.07	13.48 ± 0.81	14.62 ± 0.80

. Since seam joints along the warp threads are more often implemented in the garment industry, strength tests were carried out for clothing packages in the warp direction only.

2.4. Determination of the Multidirectional Drape Coefficient

The tests were carried out for each fabric variant with or without an adhesive insert and then for the fabric packages with seams. The test was performed on the drape meter in accordance with PN-73/P04736 [23]. To carry out the test, three specimens with a diameter of 200 mm each were cut from the fabric, and a circle with a radius of 70 mm was marked in the center.

Samples with seams were cut in such a way that the seam was applied along the sample diameter. The specimen was then placed between the support disc and the clamping disc, and the measurement was taken. The three specimens were taken for measurement of each sample package variant (i.e., without a seam and with a particular seam). The values of multidirectional drape coefficients were calculated according to Equation (1). The test was performed for the right and left sides of each prepared specimen (six repetitions), and the arithmetic mean was calculated.

Multidirectional drape coefficient K_u:

$${\mathrm{K}}_{\mathrm{u}}={\displaystyle \frac{\pi r^2-S}{\pi (r^2-r_1^2)}} \times \mathrm{100\%}$$

(1)

where

• r₁—radius of the support disc, m.
• r—radius of the specimen, m.
• S—mean of the projection area of the tested specimen, m².

2.5. Determination of Bending Rigidity

The bending rigidity measurements were performed using the cantilever method elaborated by Peirce. The specimens for the bending rigidity test were cut from the fabric in the longitudinal and transverse directions with appropriate dimensions of 300 × 30 mm according to PN-ISO 9073-7 [24]. Specimens with seams were prepared in such a way that the seam was in the middle of the sample width. For each sample package variant, five specimens were prepared. Each specimen was measured four times (from both sides—right and left—and for both ends). Therefore, 20 measurements for each sample were performed. Measurements were taken in the weft and warp directions for the fabric without an adhesive insert and without seams, whereas for the fabric with the adhesive insert and with seams, the bending length was determined in the warp direction only. The measurement results were read to the nearest 1 mm. Based on the overhang length, the bending length was calculated according to Formula (2). Then, the bending rigidity B was calculated according to Formula (3), and the general bending rigidity Bo was calculated according to Formula (4). All tests were conducted under normal working conditions.

C = l/2

(2)

where l is the overhang length.

Bending rigidity in one direction (warp or weft) was calculated according to Equation (3):

Bi = Mp C³ g

(3)

where

• Mp—mass per square meter.
• C—bending length.
• g—Earth acceleration (g = 9806 m/s²).

General bending rigidity was calculated as a geometrical mean:

B = (Bw × Bo) ½

(4)

where

• Bw—bending rigidity in the weft direction.
• Bo—bending rigidity in the warp direction.

3. Results

3.1. Results of the Multidirectional Drape Coefficient

Figure 6 shows the values of the multidirectional drape coefficient for the fabric alone and with successive adhesive inserts. The garment package with the adhesive insert CE 1016 deviates from the downward trend seen in the graph, which is undoubtedly related to the influence of the other properties of the garment package, e.g., its strain at break and strength, as found in an earlier study included in Table 2.

Below (Figure 7), a graphical representation of the relationship between the drape coefficient and the type of adhesive insert used is presented, as well as the order in which the garment package was prepared with seam 1.01.01.

Analyzing the values of the drape coefficient for samples with seam 1.01.01, one can see a decrease in the value of the drape coefficient for garment packages compared to the fabric without the adhesive insert. With the use of thicker and thicker adhesive inserts, the drape coefficient decreases. The garment package with the CE 1016 adhesive insert is characterized by lower values of the drape coefficient than expected, thus disrupting the downward trend. This decrease is probably due to the different mechanical characteristics of the adhesive insert compared to the other adhesive inserts. The order in which the garment package is made affects the value of the drape coefficient as well.

Figure 8 shows the analogous relationship for the garment package prepared with seam 2.02.10.

For samples with seam 2.02.10, the value of the drape coefficient decreases with the use of thicker adhesive inserts. For the order in which the garment package was made, it was observed that higher values of the drape coefficient are characterized by packages made in the order of undergluing → sewing than those made in the order of sewing → undergluing.

Figure 9 shows the dependence of the drape coefficient on the type of adhesive insert used and the order in which the garment package was prepared with seam 2.04.05.

For samples with seam 2.04.05, the value of the drape coefficient decreases with the use of thicker and thicker adhesive inserts (as for the other seams). As in the case of previous seams for the order in which the garment package was made, it was observed that the higher values of the drape coefficient are characterized by packages made in the order of undergluing → sewing than those made in the order of sewing → undergluing (as before).

Student’s t-test was carried out to check whether the differences in drape values between the two bonding techniques were significant. First, Fisher’s exact test was performed to check whether the results are from the same population. The results of Fisher’s exact test are given in

Table 4. Results of Fisher’s exact test for the drape variances in both bonding techniques.

Kind of Adhesive Insert/Type of Seam	1.01.01	2.02.10	2.04.05
CE 1016	4.04	3.75	1.35
CE 1026	4.20	1.01	1.44
CE 1036	4.15	4.04	1.18

, whereas the results of Student’s t-test are presented in

Table 5. Results of Student’s t-test for the drape differences obtained from both bonding techniques.

Kind of Adhesive Insert/Type of Seam	1.01.01	2.02.10	2.04.05
CE 1016	0.07	1.65	3.24
CE 1026	4.16	1.46	0.21
CE 1036	0.41	1.35	1.23

. The number of measurements was n = 6.

From the results of Fisher’s exact test (F < F_0.95 = 5.21), it can be concluded that at the significance level α = 0.05, there were no significant differences between variances in all of the cases, meaning that all of the samples belong to the same population and Student’s t-test can be applied to investigate differences between the mean values of drape for both techniques.

For Student’s t-test in the majority of cases, t < t_0.95 = 2.23 at degrees of freedom k = 10, so it was concluded that the differences were not statistically important. Only in two cases, for the fabric package with adhesive insert CE 1026 and seam type 1.01.01 and the fabric package with adhesive insert CE 1016 and seam type 2.04.05, were the differences statistically significant at the significance level α = 0.01 (t > t_0.99 = 3.17).

3.2. Results of Bending Rigidity

Figure 10 shows the dependence of bending rigidity on the type of adhesive insert applied for the fabric and seamless garment packages. The bending rigidity in the warp direction shows higher values than the bending rigidity in the weft direction. The garment package with the adhesive insert CE 1016 is distinguished by the highest value of bending rigidity; the lowest value of bending rigidity is the fabric without an adhesive insert.

Figure 11 graphically illustrates the bending rigidity values for the fabric itself and the garment packages with seam 1.01.01. The order of making the garment package significantly affects the value of bending rigidity. For the order of undergluing → sewing, higher values of bending rigidity were observed than for the order of sewing → undergluing. For the clothing package with the adhesive insert CE 1016, the differences in bending rigidity values are the smallest, while for the other two packages, they are significantly higher. For the garment package with the adhesive insert CE 1016, the bending rigidity for the order of undergluing → sewing is greater by 17% compared to the order of package preparation sewing → undergluing; for the garment package with the adhesive insert CE 1026, the bending rigidity is greater by 355% compared to the order of package preparation sewing → undergluing, and for the garment package with the adhesive insert CE 1036, the bending rigidity is greater by 328% compared to the order of package preparation sewing → undergluing.

Figure 12 shows the dependence of bending rigidity on the type of adhesive insert for the fabric sample and clothing packages with seam 2.02.10. Garment packages with seam 2.02.10 have higher values of bending rigidity compared to garment packages with seam 1.01.01. Similarly, as before, the order of making the garment package affects the value of bending rigidity. For the order of undergluing → sewing, we can observe higher values of bending rigidity than for the order of sewing → undergluing in two cases (CE 1026 and CE 1036). For a garment package with the CE 1026 adhesive insert, it is 167% higher than for the order of package preparation sewing → undergluing, whereas for the garment package with the CE 1036 adhesive insert, it is 208% higher than for the order of package preparation sewing → undergluing.

Figure 13 shows the analogous values for the fabric sample and clothing packages with seam 2.04.05. The values of bending rigidity for packages with seam 2.04.05 have the largest values among all of the clothing packages with seams, which is related to the increase in the layer number in the seam. In relation to the order in which the garment package was made, differences in bending rigidity values are evident. For the order of undergluing → sewing, the bending rigidity values for garment packages are much higher than for the fabric sample itself.

Student’s t-test was carried out to check whether the differences in bending rigidity values between the two bonding techniques were significant. First, Fisher’s exact test was performed to check whether the results are from the same population. The results of Fisher’s exact test are given in

Table 6. Results of Fisher’s exact test for the bending rigidity variances in both bonding techniques.

Kind of Adhesive Insert/Type of Seam	1.01.01	2.02.10	2.04.05
CE 1016	2.09	1.63	1.45
CE 1026	2.08	1.75	1.70
CE 1036	2.09	2.03	1.53

, whereas the results of Student’s t-test are shown in

Table 7. Results of Student’s t-test for the bending rigidity differences between both bonding techniques.

Kind of Adhesive Insert/Type of Seam	1.01.01	2.02.10	2.04.05
CE 1016	3.64	4.64	46.33
CE 1026	29.21	15.73	64.98
CE 1036	45.37	27.12	47.02

. The number of measurements was n = 20.

From the results of Fisher’s exact test (F < F_0.95 = 2.09), it can be concluded that at the significance level α = 0.05, there are no significant differences between variances in a majority of the cases (in two cases F = 2.09), so the majority of samples belongs to the same population and Student’s t-test can be applied to investigate differences between the mean values of drape for both techniques.

For Student’s t-test among all the test variants, t > t_0.99 = 2.71 at degrees of freedom k = 38, so differences between the two bonding techniques are statistically important at the significance level α = 0.01.

3.3. Influence of Bending Rigidity on the Drape Coefficient

Below, there are figures showing the relationship between bending rigidity and the multidirectional drape coefficient for the fabric itself and clothing packages without seams, Figure 14, and those with seams, Figure 15, Figure 16 and Figure 17, respectively.

For fabric samples and clothing packages without seams, it was observed that as the bending rigidity increases, the value of the drape coefficient decreases. As the mass per square meter increases, the value of the drape coefficient also decreases.

For specimens with seam 1.01.01, the values of the drape coefficient for garment packages are lower than for the fabric itself. In Figure 16, an analogous graph is presented for seam 2.02.10.

For the samples with seam 2.02.10, it was observed that as the bending rigidity increases, the values of the drape coefficient take on similar values regardless of the type of adhesive insert used, but the drape coefficient values for the order of package sample preparation undergluing → sewing are greater than in the opposite case.

For specimens with seam 2.04.05, it was observed that as the bending rigidity increases for clothing packages, the value of the drape coefficient decreases. This trend is valid for both bonding techniques, but still, the values of the drape coefficient are higher for the order undergluing → sewing than for the opposite one.

4. Discussion

The values of bending rigidity depending on the bonding technique are higher for the sequence undergluing → sewing in comparison with the order sewing → undergluing. This happened because with the first technique, each layer in the seam was underglued, so the seam was thicker and more complex. Considering only the garment packages made in the order of undergluing → sewing, it can be seen that the bending rigidity value increases with the use of thicker and thicker adhesive inserts. In summary, if bonding is performed before sewing, more layers have to be sewn, so the package becomes stiffer. Differences between the bending rigidity values of the packages are statistically significant.

Based on Figure 6, Figure 7, Figure 8 and Figure 9, we can observe that thicker packages had lower drape coefficient values. A thicker fabric package creates fewer folds, whereas a thinner fabric package creates more folds and has a lower drape coefficient value. For the order in which the garment package was made, it was observed that the higher values of drape coefficient (shallow folds) are characteristic of packages made in the order of undergluing → sewing than those made in the order of sewing → undergluing (as before). Differences in drape for both techniques are not statistically significant. If a clothing designer cares about good drapability and many folds, they should use the second bonding technique. Nevertheless, the second bonding technique cannot always be applied to the industrial process due to economic and work organization reasons.

In the paper, we also tried to answer the question of why the use of more complex seam types increases bending rigidity but has less effect on the drape coefficient. As mentioned above, a more complex seam means it has more layers, which creates a stiffer fabric package. A stiff fabric package creates fewer folds under its own weight. If the fabric package is stiff enough (not flexible), the differences in the depth of folds are less visible.

5. Conclusions

The following conclusions can be drawn directly based on the study presented:

• The mass per square meter affects the value of the drape coefficient. As the mass per square meter increases, the value of the drape coefficient decreases, i.e., the sample becomes stiffer and creates fewer folds.
• By undergluing the fabric even with the thinnest adhesive insert, the bending rigidity value increases, i.e., the sample becomes stiffer. With the use of thicker and thicker adhesive inserts, the bending rigidity increases, but the multidirectional drape coefficient decreases.
• Clothing packages prepared in the order of undergluing → sewing show higher bending rigidity values than the clothing packages prepared in the order of sewing → undergluing.
• The order of garment package preparation affects the value of the drape coefficient. For packages prepared in the order of undergluing → sewing, the values of the multidirectional drape coefficient are slightly higher than for packages prepared in the order of sewing → undergluing, but the observed differences are not statistically significant.
• The use of seams increases the value of bending rigidity. With the use of more complex seams (with more fabric layers in the cross-section), the bending rigidity increases. The complexity of the seam (layer count) does not significantly affect the value of the multidirectional drape coefficient of clothing packages.

The presented research was carried out for a limited assortment of fabrics (only cotton fabric) and adhesive inserts, but to obtain general conclusions, the investigation should be continued for a wider sample package representation (synthetics or fabrics made of blended yarns). Some of the presented conclusions were expected intuitively, although we did not find in the literature any investigations measuring the properties of sample packages (like the bending rigidity and multidirectional drape coefficient) with the introduction of different kinds of seams, as well as with different sequences of bonding techniques. This is the novelty of the presented research. The second technique, in many cases, gives better results concerning the appearance of ready garments. Nevertheless, the second bonding technique cannot always be applied to the industrial process of “pret-a-porter” clothing. It can be more often applied to “haute couture” creations, where economic and work organization aspects do not play so much of a role.