In this paper, the effect of false-twist texturing parameters (texturing speed, heater temperature, draw ratio and disc-to-yarn speed ratio (D/Y ratio)) on the structure and crimp properties of polyester yarn has been studied using a high temperature heater and high texturing speeds. Textured yarn was analyzed and characterized in terms of the degree of crystallinity, degree of orientation and crimp properties (crimp contraction, crimp module and crimp stability). The most important parameters, significantly affecting yarn temperature and its uniformity and thus textured yarn structure and crimp properties, are texturing speed and heater temperature. Depending on these texturing parameters, the degree of crystallinity and orientation varied in the range of 24.48 to 36.66% and 0.371 to 0.595, respectively. The crimp characteristics increase with the increase in heater temperature, and decrease with the increase in texturing speed. The effect of draw ratio and D/Y ratio on the textured yarn structure and properties is less pronounced. Obtained results show that partially oriented polyester yarn used in this study can be textured at significantly higher texturing speed (up to 1100 m/min) than the standard texturing speed (up to 700 m/min) used for the yarn count examined.

Predicting the behavior of geotextiles made of polyesters and polypropylene fibers is described by differential equations derived from mechanical models. Thereby, we describe the behavior of geotextiles up to the elastic limit. The elastic limit represents the permissible load which the geotextile material may be subjected to during exploitation, and without distorting its structure. The elastic limit is defined by analyzing the stress–strain curve of analyzed geotextiles. Nonwoven geotextile materials of polyester and polypropylene fibers with surface mass of 150, 200, 250, 300 and 500 g/m² were used as experimental material.

The influence of using formic, oxalic, citric, tartaric, hydrochloric, nitric, sulphuric and phosphoric acid for dyebath pH adjustment was investigated upon the dyeing of polyester fabric with CI Disperse Yellow 60. The positions of colour in CIELab coordinates of the samples dyed with the addition of tested acids were assessed and compared to those dyed with the addition of acetic acid. It was found that the differences in dyeabilities obtained with the addition of citric, oxalic, hydrochloric, nitric and sulphuric acid are entirely acceptable according to both M&S 83A and CMC (2:1) standards in comparison to the dyeability obtained with the addition of acetic acid.

The properties of textured POY PES multifilament yarns are conditioned by texturing temperature, texturing speed, stretching degree and by the ratio of disc peripheral speed and yarn speed. In the paper attention is focused on crimping of yarns. New method for defining crimping limits is proposed. The method is based on the flow analysis of the force-elongation function. POY multifilament polyester yarns, having the fineness of 167f36x1 dtex were analyzed. The texturing of PES multifilament yarns was performed using different first heater temperatures (350 oC, 400 oC, 450 oC) and maintaining the constant temperature of the second heater (180 oC), then with different texturing speeds (500 m/min, 600 m/min, 700 m/min, 900 m/min, 1000 m/min, 1100 m/min), using different ratio of the disc circumferential speed to yarn speed (2.15, 2.20, 2.25) and at the extension degree of 1.665.

Deformations of woven materials occur in the process of forming fabrics into more complex textile structures, as well as during the exploitation of finished products. Several factors influence the deformation properties of textile materials. The key factors are the properties of the yarn used, the construction of the fabric and the density of the warp and weft threads. The anisotropic properties of woven materials impose the need to analyze the deformation in the direction of the warp and in the direction of the weft of fabric. In addition, the research includes the analysis of the deformation of woven materials at an angle of 45 ° in relation to the direction of the warp. The results of the research showed that increasing the density of the weft threads leads to an improvement in the characteristics at the limit of yielding and breaking in the direction of the weft and at an angle of 45 °. Based on the obtained results, dependencies were proposed that can be used to predict the deformation of woven textile materials in a plain weave using tensile force in the direction of the warp, in the direction of the weft and at an angle of 45 °.