Abstract

The breaking force of warp yarns taken per segments on the loom is measured using three weaves from the same warp on different looms. To simulate the deformation of warp yarns, samples from the warp beam are taken and, after various conditions of cyclic stress on a dynamometer, the most approximate degree of warp deformation is that which occurs in the weaving process per segments on the loom and per weave types. The F-test, t-test, χ2-test, and correlation coefficient reveal that there are no differences among breaking force values of the yarns from the looms or on yarns after cyclic stress and relaxation measured on the dynamometer, meaning that deformation imparted to the warp on the loom during weaving is very similar. Deformation caused by friction among yarns and imparted by metal pieces is not discussed here, but is included in the deformation caused by stress. Under the same conditions of cyclic stress, the elongation of the warp during stress in the segments of the loom is tested, and the conclusion is reached that elongation follows yarn deformation almost linearly. Investigations involve the same weaving conditions on the same loom and with the same warp, employing the three weaves. Dynamic tension of the warp is measured for each weave in the course of weaving, and the change in tension caused by changing the weave is registered.

In this paper, the synthesis, characterization and application of a copolymer as a sizing agent obtained by the grafting of methacrylic acid on hydrolyzed potato starch were investigated. Starch hydrolysis was performed in order to reduce the average molar mass (i.e. the size of the macromolecules). Grafting of methacrylic acid on hydrolyzed potato starch was performed to obtain a product that can be effective in textile processing, for example, for sizing yarn. The grafting of the monomer has been confirmed by Fourier transform infrared spectroscopy spectra of hydrolyzed and grafted potato starch. The distribution of molar masses was determined chromatographically. The results obtained by sizing of cotton yarn with the new starch agent confirmed its higher breaking strength, elongation, abrasion resistance, reduced hairiness, better evenness, etc. Grafted hydrolyzed potato starch (almost identical to the commercial medium) exhibits better performance as a potential agent for sizing cotton yarn than ungrafted hydrolyzed starch.

The purpose of sizing is to improve physical-mechanical parameters of warp threads, thus, decreasing thread breakage rate in weaving [1][2][3][4][5]. Good sizing consists not only of sizing, but also of drying, which has not been fully investigated to date. As size particles are found in the solution, they move over the whole cross-section of the yarn during the drying process. Yarn drying has changed due to the development of sizing machines. The first dryers were mostly convection ovens in which air currents were used for warp drying. Today, contact drying is the most widely used. It was of great interest to perform research into the possible usage of microwave in the warp sizing, with regard to the performance as well as economical reasons. No such paper has been found in the published literature.For the purpose of this study, we used a newly constructed sizing laboratory device presented in Figure 1. Various types of dryers, convection (I), contact (II) and microwave (III), could be applied after the sizing process. The sizing device enabled a continuous control and regulation of the following parameters: sizing velocity, temperature of the sizing agent, tension and inlet moisture of the warp, outlet moisture of the warp, after drying and drying intensity. The dryer should dry the sized warp in a short period of time to the moisture content it had before sizing, or even less than that. The highest energy consumption in sizing is in the drying procedure. Therefore, the research and development of microwave drying of the sized warp could lead to a considerable reduction in energy consumption.The idea of microwave (MW) application for textile finishing processes first originated in the 1970s when cellulose fabrics were treated with Durable Press (DP) finishing agents and cured in the microwave oven. Although these first results were promising, the idea was abandoned until 1995, when Miller patented his Pre-set process without being aware of the earlier patent. Both cases involved garment microwave treatment, but they were abandoned because the efforts to control the process failed. Until now, microwaves have been used for textile finishing in the combined desizing, scouring and bleaching processes, durable press finishing [6, 7], dyeing and drying processes, as well as for eradication of insects from wool textiles. 1 Microwave dielectric heating is based on activation of polar molecules in treated medium (polarization phenomenon). In a microwave electromagnetic field oscillating at 2.5 GHz, which is a preferred frequency for heating applications, the charge changes polarity nearly five billion times per second. Under the influence of a high frequency Abstract The paper describes our research of microwave usage in drying the size pick-up. An analysis of three different drying processes in relation to physical-mechanical properties of sized yarn has been carried out. Under the same sizing conditions, but different drying methods, the following parameters were determined: breaking force, elongation at break, abrasi...