M. Stamenkovic’s research while affiliated with Technical Faculty in Bor and other places

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. [Projekat Ministarstva nauke Republike Srbije, br. TR 34020: The Development of New and the Improvement of the Existing Technological Processes for the Production of Technical Textiles]

The bentonite was treated in different ways and the changes in structure were monitored. Acid activation with sulphuric acid of investigated bentonite caused the increase in specific volume of micropore-mesopore. It was shown that activation by acid obtained at a constant temperature and constant period of time provides the possibility to obtain samples of bentonite of searched porosity only by changing the concentration of sulphuric and hydrochloric acid. By thermal activation of bentonite clay in the temperature range 100-1100 0C, samples of desired porosity were acquired. [Projekat Ministarstva nauke Republike Srbije, br. 174007i br. TR 34020]

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.

Organic modification of mineral clay using the monomer ethenyl acetate was performed. The exchange of inorganic interlayer clay cations was achieved using the cationic surfactant Genamine CTAC and Asepsol. Aiming to investigate the influence of organic modifications on adsorptive clay properties, dried composites of clay/ethenyl acetate, with different percentages of clay were soaked in distilled water. The influence of the temperature on the adsorptive properties of organoclays was also followed. The adsorptive properties of the obtained composites of organoclays with Luviskol, Carbopole and purine were investigated along with their capability for removing Pb2+ from water in charged systems. [Projekat Ministarstva nauke Republike Srbije, br. TR 34020, br. 172047 i br. 174007]

The purpose of this paper was to determine the unknown concentration of dichlortriazinyl reactive dyes, namely Reactive Yellow 22 and Reactive Blue 163, in dyed cotton fabric. The samples of cotton fabric were dyed individually with each dye as well as with a mixture of two dyes. The unknown concentrations of dyes were determined by measuring the corresponding reflectance values of dyed fabric samples and then using the relation between the concentration and reflectance values of the samples. The method set by Kubelka and Munk was used. The accuracy and repeatability of the concentrations determination were calculated by the statistical processing of the data obtained by measurements. Relative errors of individual determination of Reactive Yellow 22 and Reactive Blue 163 were 3.66 and 5.94% respectively. Relative errors in determination of Reactive Yellow 22 and Reactive Blue 163 in a mixture were 3.47 and 3.19%, respectively. The results showed that reflectance spectrophotometry can be successfully used as the method for concentration determination of Reactive Yellow 22 and Reactive Blue 163 in dyed cotton fabric and can therefore be applied as the shade control method in dyeing.

Adsorption behaviour of direct dye on cotton (dyeing) vi,as examined in order to gain data on colour binding mechanism and defining conditions of natural fibres dyeing process without any usual additions - electrolytes and other auxiliaries, as the basic precondition for optimising conventional or alternative, ecological additives. Adsorption was conducted under various conditions. It was determined that it depends upon contact time, initial dye concentration and adsorbent amount. The longer contact time is the more colour transfers on the yarn. Dye concentration in solution descends during the adsorption process. There is continuous growth of removed dye amount along with adsorbents amount. Characteristic illustration gained from Freundlich isotherm has confirmed that this model provides enough precise description of experimental data for direct dye in comparison to Langmuir isotherm.

Dyeing of polyester fabric is carryng out in slightly acidic medium; the dyebath pH value is adjusted to 4.5-5.5, which results in the huge amount of acidic industrial wastewater. In this paper, dyeing of polyester knitwear with four disperse dyes in the pH range 4.5-7, in order to reduce the amount of acid used in the dyeing process, was investigated. Colour differences between the samples dyed at pH 6.0 and 7.0 and one dyed at pH 4.5 were asseessed using the technique of reflectiometry and expressed in terms of CIELAB coordinates and their acceptability were determined according to M&S 83A and CMC (2:1) standards. It was found that at pH 6.0 and 7.0 Disperse Yellow 3 and Disperse Yellow 23 produced dyeabilities which were acceptable according to both M&S 83A and CMC (2:1) standard in comparation to the dyeability obtained at pH 4.5. Disperse Yellow 5 and Disperse Yellow 60 did not produce acceptable dyeabilities neither at pH 6.0 nor pH 7.0, according to both M&S 83A and CMC (2:1) standard, in comparation to the dyeability obtained at pH 4.5. It can be assumed that polyester dyeing with Disperse Yellow 3 and Disperse Yellow 23 can be carried out at pH 6-7, which will reduce the wastewaters acidity, as well as the amount of neutralising agent recquired for their neutralisation. © SGEM2011 All Rights Reserved by the International Multidisciplinary Scientific GeoConference SGEM.

Defining thresholds for yarn strain in manufacturing process is crucial for appropriately adjusting these processes and keeping high yarn quality. That is the main reason why the issue has drawn so much intention. The knowledge of elasticity limits and yield points is very important for the optimization of the production process and further twisted woolen yarns processing. Therefore, this paper defines the limits for elasticity and yield points and breaking forces of woolen yarns with the linear density of 21x2 tex, 23x2 tex and 25x2 tex, obtained by two-for-one twisting method. The interrelationship between the forces and the elongations at elasticity limits, yield points and breaking force of these yarns are also analyzed. Besides, on the basis of experimental results and equations, real mathematical dependences are set, which can be used to predict forces and elongations of woolen yarns at elasticity limits, yield points and breaking limits.

In the winding process, on its way from the spinning tube to the bobbin, yarn was exposed to different influences that caused various tensions in different sectors. The increase in the tension force brought about a decrease in the linear density of all the wound yarns. All of this influenced the resulting tension with which the yarn was wound onto the bobbin. After two weeks, the deformation characteristics of these yarns were examined. Also determined were values of the breaking forces and relative elongation at break for all the linear density. On the basis of a F-ε curve, elasticity limits were defined as well as the yield point of the wound yarns analysed. Making use of the recommendations of some investigators, it was possible to project the breaking forces, elasticity limit force and forces at the yield point. The quality control of raw materials, process control and yarn quality control are a necessary help for the technologist to establish a well-set winding process. It is only on the basis of the exact parameters provided by such controls that it becomes possible to intervene correctly and in time in order to achieve optimal results and obtain good quality wound yarn.