INVESTIGATION OF STRENGTH CHARACTERISTICS OF SEAMS IN PROTECTIVE CLOTHING MADE FROM RECYCLED MATERIALS

ABSTRACT

This article is dedicated to determining the strength of seams in special clothing made from recycled materials. The experiment utilized untreated and hydrophobic cotton fiber materials. The aim of the study was to assess the impact of fabric types and stitching parameters on the strength of joints subjected to operational loads. Various joining methods were employed in the experiments, taking into account fiber types, weave density, and processing methods. The results demonstrated that selecting optimal combinations of materials and sewing technologies can increase seam strength to a level comparable with garments made from primary raw materials. The obtained data will be applied in the production of field clothing for workers in the agro-industrial sector.

АННОТАЦИЯ

Данная статья посвящена определению прочности соединительных швов специальной одежды из вторичных материалов. В эксперименте использовались необработанные и гидрофобные материалы из хлопкового волокна. Целью работы являлось определение влияния типов тканей и параметров строчки на прочность соединений, подвергаемых эксплуатационным нагрузкам. В ходе экспериментов применялись различные методы соединения, учитывались типы волокон, плотность переплетения и вид обработки. Результаты показали, что выбор оптимальных сочетаний материалов и технологий прошивки позволяет повысить прочность швов до уровня, сопоставимого с изделиями из первичного сырья. Полученные данные будут использованы при внедрении в производство полевой одежды для работников агропромышленного комплекса.

Keywords: Recycled material, seam strength, tensile strength, tensile elongation, hydrophobic fabric.

Ключевые слова: вторичный материал, прочность шва, разрывная нагрузка, разрывное удлинение, гидрофобная ткань.

Introduction

During the operation of special clothing for agricultural workers, it is important to preserve the appearance and reliability of the product throughout its entire service life. Workwear is an engineering system consisting of individual parts (details) connected by structural and technological joints (technological units of the structure). The reliability of the entire system will depend on the reliability of its elements, and external force impacts will be distributed among individual elements. The development of textile materials for field workers' special clothing in the agricultural sector requires, first of all, the creation of new durable materials that meet the modern level of protective properties under the influence of various adverse physical and mechanical environmental factors. In it, the employee should feel maximally protected from adverse factors, the clothing should be comfortable and help the employee cope with their range of responsibilities [1].

Textile materials processed from recycled cotton raw materials open up great prospects for expanding the range of special clothing [2]. Consequently, the development of special-purpose products for the agro-industrial complex is a pressing task for sewing materials science. When analyzing the suitability of materials for field workers' special clothing, reliability as a property to retain its original value is of greatest importance: wear, mechanical wear of textile material in places exposed to aggressive environments, strength of seams in places subjected to increased workload. The strength of the connecting joints should not be lower than the reliability of the fabric from which it is made. In this regard, it is important to assess the strength of the connecting joints of the field special clothing of agricultural workers made of recycled materials, taking into account the service life and operational impacts.

The strength of the design of special clothing and individual units is influenced by various factors [1]. All of them affect the means of joining differently and ultimately lead to a decrease in the strength of the joints of the product parts. For example, dust not only contaminates clothing but also penetrates the areas where parts are joined. As a result of the cyclic loads acting on the product, dust causes abrasive action on the means of joining parts. The effect of thermal factors leads to aging and changes in the structure of materials connecting parts - sewing thread polymer, adhesive in adhesive joints, or polymer of the base material in welded joints [3]. It is important to note that these influences occur during the action of external and sometimes internal stresses or under their influence.

The quality of threaded connections in the design of the workpiece is determined by the structure of the seam, the type of interweaving, the properties of the fabric and thread, the parameters of the seam, and the technological modes [4]. The thickness of the fabric affects the value of the structural additions and the seam structure. The criterion of seam reliability during stretching is the work function for tearing. The strength of the connecting joints is important for the operational characteristics of clothing and includes the main structural joints. The tensile strength is the main strength indicator considered when evaluating fabric, which allows determining their durability, i.e., resistance to mechanical influences [5].

One of the requirements for special clothing is to keep its owner dry and reliable during operation after exposure to light and weather conditions. Therefore, studying and predicting the strength characteristics of special clothing after exposure to light and weather is a pressing task in researching recycled materials. The purpose of the proposed work is to determine the strength of the connecting joints of the special clothing of agricultural workers, obtained from recycled materials, taking into account operational impacts.

Materials and methods

As a research object, samples of fabrics from recycled raw materials containing 100% cotton in the warp, 50% cotton, and 50% viscose in the weft, treated with a water-repellent emulsion based on perftoracrylate and diisocyanate oligomers (PDOE) [6], were selected. The same fabric was subjected to the experiment before and after applying the water-repellent impregnation (Table 1). These fabrics, based on physical-mechanical and structural studies, were previously recommended for the production of field workers' special clothing [7].

Table 1.

Physical and mechanical properties of the studied materials from recycled raw materials

The authors have conducted a thorough analysis of working conditions and the external environment, as well as a systematic study of a complex of hazardous and harmful factors affecting field workers [1]. The topography of wear of the connecting seams of existing special clothing parts was studied (Fig. 1) and it was established that during the work process of workers, the following seams on special clothing parts experience great tension: the side, shoulder seam of the jacket and sleeve, the armhole seam, the step and side seam of the trousers, the middle seam of the trousers, etc.

Figure 1. Seam rupture areas in special clothing

Threaded connection of the samples was performed on a universal DDL 8700 JUKI plush stitch sewing machine. All seams are made with a single thread (cotton-lavsan No44LX).  The research was conducted on 4 fabric samples with 16 connecting and edge threaded seam constructions. When choosing seam designs and technological allowances for processing, the peculiarities of nodal processing of special clothing, fabric shedding (open cuts were basted with machine chain stitch), clothing cut and silhouette, and the share direction in the clothing cut details were taken into account [3]. To verify the elongation strength of the stitch seams, the samples were cut at different angles to the fabric's direction: along the warp threads (longitudinal seam); 90° to the warp threads (transverse seam) [8]. The seams are made in two variants: stitched and stitched with a different number of stitches per 10 mm: 4, 3, 2,5. Studies of the tensile strength of threaded connections were conducted on five experimental samples of special clothing before destruction, then the average values of the obtained results were determined. The results of experimental studies of joint strength are presented in Table 3.

The tensile strength of the seams was investigated using standard methods [8] on the "Autograph" (Japan) tear machine. Table 2 shows the characteristics and diagram of the seams used in special clothing.

Table 2.

Characteristics and patterns of secular clothing seams

Results and discussions

The results of the study of the strength properties of threaded seams of special clothing on fabric samples from recycled raw materials showed that all seam samples are characterized by high tensile strength (420...570 N) and elongation at break, resistance to tearing (61...51%) (Table. 3).