STUDY OF THE PHYSICAL-MECHANICAL PROPERTIES OF DENIM FABRIC WITH STRETCH CHARACTERISTICS

ABSTRACT

The article analyzes the features of the use of everyday clothing and comfort criteria, which are very important for consumers. It has been established that the period of wearing everyday clothes can be long and vary in terms of wear resistance. Convenience is also considered one of the requirements. It is assessed on a number of parameters such as the elasticity and breathability of denim. As a result of the study, it was determined that an increase in the amount of lycra in the fiber composition of the fabric affected its flexibility and breathability. Increasing these indicators increases the comfort and elasticity of denim fabrics.

АННОТАЦИЯ

В статье проанализированы особенности эксплуатации повседневной одежды и критерии  комфортности, которые очень важны для потребителей. Установлено, что срок ношения повседневной одежды может быть длительным и варьироваться по показателям  износостойкости. Удобство также считается одним из требований. Он оценивается по ряду параметров, таких как эластичность и воздухопроницаемость джинсовой ткани. В результате исследования определено, что увеличение количества лайкры в составе волокон ткани повлияло на ее гибкость и воздухопроницаемость. Увеличение этих показателей повышает комфортность и эластичность джинсовых тканей.

Keywords: Stretch denim, lycra; fabric shrinkage, breathability, stretch, elongation at break, abrasion resistance, fabric wrinkling.

Ключевые слова: Джинсовая ткань стрейч, лайкра, усадка ткани, воздухопроницаемость, растяжение, удлинение при разрыве, устойчивость к истиранию, образование складок на ткани.

Comprehensive measures are being taken in our republic to modernize the textile industry, increase the production of high-quality, competitive and export-oriented finished products from local raw materials, and certain results are being achieved. Production indicators for 2021. 1,005 thousand tons of cotton fiber were processed and 862 thousand tons of cotton yarn were spun, of which 716 million sq.m. cotton fabrics, 204 thousand tons of knitted fabrics, 2 billion pieces of clothing and knitwear, 458 million pairs of socks.

Denim, the favorite fabric of the youth, has indeed come a long way. Consumer choice, although erratic and unpredictable, has remained much the same when choosing jeans as a garment [1]. The scope of denim clothing is expanding every year, and its share in the world market has increased unpredictably over the past few decades. In recent years, the fashion trend has shifted from denim to stretch denim (jeans with elastane) [2]. Stretch denim typically adds an elastic component (such as elastane) to the fabric to provide a degree of stretch to the garment [3, 4]. Denim is a heavy, coarse fabric made from 100% cotton yarn dyed with indigo dye [5-7]. Traditional denim is a very stiff and dense fabric with a high mass per unit area. In jeans technologies, it is mainly woven with similar cuts three up-one down (3/1) and two up-one down (2/1) [8-10]. The denim is available in attractive indigo colors and is produced in a wide range. Denim is classified in the range of 300-600 g/m2, known as heavy denim. Today, consumers demand durability and comfort in their fashion items, including jeans [11-14]. Özdil [5] investigated the stretch and coverage characteristics of denim fabrics containing varying amounts of elastane. Test results have shown that increasing the amount of elastane in denim improves stretch-related comfort. To increase the extensibility of denim, it is also possible to use yarn, the main part of which consists of lycra thread and cotton fiber with a sheath [5]. The performance and comfort factors of this garment are very important during use. In general, the ability of tissues to easily stretch in accordance with body movements, as well as to recover from stretching, are desirable properties. Elastane denim has become increasingly popular in recent years due to the demand for more comfortable clothing. Some of the earlier research focused on the effect of Lycra on the physical and strength properties of denim. Some recent research has focused on the antibacterial properties of denim. However, there has been limited research into the performance impact of Lycra-containing denim. In addition to consumer properties, this research aims to study the influence of the fabric on warp and weft density, Lycra content, as well as the stretch and recovery properties of the fabric. To do this, different properties of denim fabrics were measured with different amounts of elastane added to yarns twisted in the weave direction. Tensile properties, flow rates, and air permeability were determined. The influence of the content of Lycra on the thickness of the fabric, its uniformity, elasticity, and recovery properties was evaluated. The influence of the type of shear on the physical and strength properties of the fabric was also studied.

The relationship between the direction of twist of the warp and weft threads, in particular, their dependence on shear, is considered. Twisting the thread to the right or left differently affects the surface structure, appearance, and pattern of the fabric in different cases. These figures are reflected in different crops. There are weft types for different jeans designs, such as the analysis of a woven weft formed by placing three wefts on a loom to form a twill weft that is one weft more than a canvas weft. The resulting clippings and their full images are shown in Figs. 1 a, b. As can be seen from these cuts, the number of threads in the warp is equal to the number of threads in the warp. RT =RA= 4, single coatings move one thread relative to each other, i.e. S=1.

Figure 1. 1/3 cover, twill bevel

In smooth fabrics, the supporting surface is formed by comb-like ridges of a wave of threads. Shear has a significant effect on the supporting surface of the fabric, i.e. the longer the coating, the larger the bearing surface area. During tissue friction, the supporting surface is first damaged. Fabric with a large surface area is resistant to friction. In addition, the surface area of the backing affects the breathability of the fabric. Breathability is an important property of the fabric and is expressed in the ability to pass air and provide good air exchange in clothing, maintaining a certain ratio of moisture and air in the air space under the fabric. The thickness of the elastic denim was measured with a thickness gauge (Karl Schroder KG) at a pressure of 0.5 kPa according to BS EN ISO 9073-2:1997. Yarn density was measured using a sampling window according to ISO 7211/2-1984. The weight per unit area (g/m²) was measured using a 100 cm² round sample according to ISO 3801-1977 standard test method.

The wear resistance of the samples was determined. To determine this property, we used the M235/3 friction tool. This equipment is used to test the abrasion resistance of various types of fabrics. The air temperature in the room should be 20±3 °C, and humidity 60±5%. Samples of 0.38 mm and 0.140 mm are cut out on special cutting equipment. During the experiment, the applied loads should be selected based on the thickness of the fabric (9 or 12 kPa). When casting the upper part of the machine, it is necessary to pay attention to the correct fall of the metal balls.

We used the AP-360SM Air Permeability Tester to determine the air permeability of the samples. This device is a special device for testing the breathability of various types of fabrics. The air temperature in the room should be 20±3 °C, and humidity 60±5%. Adjustment range 0.5-390 cm³/cm² sec. The sample is prepared in the following size: 160x160mm. When conducting an experiment, it is necessary to select a nozzle of the required diameter, based on the thickness of the tissue. When using the equipment, the water level must be at the indicated location. The machine operates from a power source with a voltage of 220 V and a frequency of 50 Hz.

The creasing of the samples was determined on the device AB-6. This tool is used to test the folding properties of various types of fabrics. To use the device, the air temperature in the room must be 20±3 °C, and humidity 60±5%. The sample is prepared with a size of 150x40 mm. The sample is then placed between the glass plates in a bent position. A weight of 500 g is placed on top and held for 5 minutes. Then the sample is taken from a glass container and clamped in a special clamp. After 5 minutes, the results obtained are calculated using the following formula for the wrinkle resistance coefficient.

                                                               (1)

here, a - opening angle

k- anti-wrinkle coefficient.

In the research work, based on the technological factors used in the previous work, and from the selected raw materials, denim samples were made in 5 versions in the conditions of an educational laboratory and a manufacturing enterprise, and their physical and mechanical characteristics have been studied.

In research work in order to create a technology for the production of fabric from mixed fiber with stretch using cotton and chemical polyester and elastane yarns grown in our country, work is underway to produce and expand new ranges of fabric. This, in turn, creates opportunities for expanding and localizing the range of fabrics, obtaining denim from a new range of fibers of a mixed composition.

Table 1.

Physical and mechanical properties of experimental fabric samples.

The physical and mechanical parameters of the samples of experimental fabrics were determined in the testing laboratories of the Uzbek-Turkish Testing Center LLC located in Tashkent, tensile strength, F (cN), specific tensile strength, (cN / tex), elongation at break, ɛ (%), a number of similar tests were carried out and the results were obtained (https://uzttm.uz): The physical and mechanical parameters of the obtained experimental tissue samples of 7 variants are presented in Table 1.

Based on the results of the study, the following conclusion was made. That is, option I, II, IV, V, VI, and VII of the elastic suit fabric not only has a short production technology, but also quality indicators: 100% cotton, the breathability of the fiber of 4 fabric samples is increased by 54% compared to 1 fabric sample with lycra thread, and moisture absorption is higher by 80%. The tensile strength of the fabric is 84% higher for fabric sample 1, and the fabric with the addition of lycra yarn has not only elasticity but also meets the requirements of GOST for denim fabrics in terms of consumer characteristics, appearance, and quality. indicators. Fabric samples of options 1 and 4, produced on the basis of the technology proposed in the scientific work, are woven from local raw materials and satisfy the need for costume fabrics.

It can be seen that the fabric with high elasticity frees the movement of the person. However, after the force is removed, the fabric should return to its original dimensions. The fabric with the addition of lycra stretches well and restores elasticity. Due to the fact that lycra thread has high elasticity and elastic recovery, an increase in elasticity was observed, and with an increase in the amount of lycra in the fabric, technological and hygienic factors increased.

The breathability of a fabric is the ability of a fabric to fully allow atmospheric air to pass through the fabric and reach the skin. Depending on the use of fabric, air permeability indicators are determined. For example, high breathability may be desirable for garments in hot climates. However, in cold climates, it can be negative. A high breathability value is observed in a fabric with a low content of lycra and decreases with an increase in the content of lycra. As the amount of Lycra in the fabric increases, the shrinkage of the woven fabric increases, which increases the thickness of the fabric, resulting in higher resistance to airflow. Statistical analysis showed that there was a significant difference in the breathability of the three denim fabrics with different Lycra content.

The results obtained in this study showed that the amount of Lycra has a significant effect on the physical and elastic properties of denim. The tear strength of the Lycra-containing fabric decreased across the width of the weave, while the tensile strength of the fabric increased towards the warp due to the greater fabric support provided by the weft threads. As the thickness of the fabric increased, the penetration and stiffness of the fabric increased. As the amount of Lycra in the fabric increased, the stretch, shrinkage, and uniformity increased. Methods for the production of new types of elastic fabrics "Jeans" from local raw materials are determined based on the development of fabric production technology on modern looms.

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