Omar Harzallah

Influence of Pre-wetting on the Characteristics of a Sized Yarn

The preparation of a warp yarn is a key element of the success of weaving. Under the economic pressure to which the world textile industry is subjected, an increased attention is given to the equipment, to the products and the processes used in the preparation of warp yarns for weaving. The yarn, the sizing equipment and the size must be adapted to each other, so powerful yarns able to resist the weaving requests with lower cost can be obtained. The aim of this work was the study of the mechanical behavior of sized yarns after a pre-wetting operation with hot water and the drying of these yarns on the sizing machine. First, we showed that the heat transfer coefficient was the same, no matter whether the yarn was pre-wetted or not. Pre-wetting did not decrease the production. However, despite containing less size, the yarn hairiness was reduced as compared to sizing without pre-wetting. The initial modulus of sized yarn with pre-wetting was higher than that of classically sized yarn and the sized yarn with this new technology of sizing presented a more important immediate recovery. Moreover, we studied the influence of a preliminary wetting on the structure of the size bridges between fibers by using scanning electron microscopy. Examination of the cross-section of sized yarn showed that if the yarn was pre-wetted, the bridges between fibers could be observed to a higher extent at the periphery of the yarn, which explained the good mechanical behavior.

Textile Surfaces Analysis and Modeling based on Statistical Methods: Variance Analysis and Autocorrelation Functions

Statistical analysis using between-variance are usually used in various industries. In this paper we propose to apply these statistical analysis tools to textile surfaces. Based on early theories [1— 9] statistical tools have been developed to take into account periodic and random defects observed on linear textiles. Indeed, in the textile industry the raw material presents a strong random unevenness and moreover each processing step introduces its own periodic irregularity (e.g. faults due to an elliptic roller or defective gear). A method for determining these irregularities is developed whereby it is possible to define the function of the variance-mass per unit area of the fibrous web if the overall mass variance of the web produced during the industrial process is known. Indeed, with the help of the autocorrelation function, the between-area-density variance function B(S) of the fibrous web can be predicted and the shape of the B(S) curve is determined. The two types of irregularities have also been examined and analyzed. Random irregularities were developed based on the functions of the most common distributions (isoprobable, equiprobable, uniform distributions). Then, the periodic irregularities have been developed and generalized. Finally, we discussed the actual industrial case known as a superposition of periodic and random irregularities.

Macro and Micro Characterization of Biopolymers: Case of Cotton Fibre

This chapter’s aim is to give the reader an overview of different methods used to characterise biopolymers based on the case of cotton fibre. It is not meant to be an exhaustive list of methods, but to give examples that illustrate as clearly as possible the most used and most efficient methods. The cotton fibre is a very complex biopolymer whose properties depend on varietal and environmental conditions. Cotton fibre is a very well adapted example to describe the different methods to characterise the morphology, the mechanical properties on single fibres or on fibre bundles and the surface properties. Reference methods are described as well as more advanced methods based on experiments which have been carried out by the authors and their co-workers.

Preparation of Cellulosic Fibers from Sugarcane for Textile Use

The production of natural fibers is not sufficient to accommodate the textile needs of the growing world population. Therefore, textile research is exploring alternative natural resources to produce fibers. Though typically known for its nutritional use, the sugarcane can also be used for textile production because of its high fiber content. The aim of our study was to extract fibers from sugarcane and to analyze their mechanical behavior. Cane particles were treated with an alkaline solution in order to get cellulosic fibers. Physical and mechanical characterizations were carried out on these fibers: linear density, fineness, tensile properties, and bending rigidity. Their microstructure was analyzed to better understand their behavior. The results showed a strong influence of extraction parameters on the characteristics of fibers. Depending on these parameters, fibers fineness ranged from 8 to 80 tex, length ranged from 19 to 62 mm, and tenacity ranged from 7 and 25 cN/tex.

Influence of wetting phenomenon on the characteristics of a sized yarn

The aim of this work is to study the effect of the addition of a wetting agent to a size solution and to the water used for the pre-wetting to know if it is possible to reduce size content of the yarn with mechanical properties allowing a good ‘weavability’. The effect on the physical and mechanical characteristics of adding the wetting agent was examined. In the tensile test, as a result of adding the wetting agent to a size solution, an increase in the Young modulus of the yarn sized classically was induced, and a decrease with a pre-wetting technique. Concerning the bending rigidity, the same conclusion as for the tensile strength has been demonstrated by using the Kawabata unit. These deteriorations have been explained by using scanning electron microscopy. Indeed, the micrographs seem to show that the fibers of yarns sized with the pre-wetting technique are coated with the size film and not bridged to themselves with the size which explained the decrease of the mechanical properties. However this coating is not recommended in the sizing process.

Development of multifunctional different cross-sectional shaped coaxial composite filaments for SMART textile applications

The aim of this study is to design a spinneret that can be used efficiently for the manufacturing of coaxial composite filaments. Poly(ethylene terephthalate) was used as resin matrix with 99.9% pure copper filament as the core. The characterization of the polymer was done to determine polymer thermal and rheological properties. Multi-shaped coaxial composite filaments were obtained after successful laboratory-scale melt extrusion machine modification and spinneret development. The cross-sectional surface and shape were analyzed with a scanning electron microscope. Coaxial filaments having the cross-section including elliptical, triangular, rectangular and circular shapes were developed. The characterization of spinneret design and coaxial composite filaments were also reported. The effect of spinneret design parameters on the cross-sectional shape of the filament were analyzed.

Performance characterization of multifunctional different cross-sectional-shaped coaxial composite filaments for SMART textile applications

The aim of this study is to investigate the effect of spinneret design parameters on cross-sectional shape and mechanical performance characteristics of coaxial composite filaments. A number of different cross-sectional-shaped metal/polymer core/sheath coaxial composite filaments were developed by changing spinneret design parameters. The cross-sectional shapes obtained were circular, rectangular, triangular and elliptical shapes. The mechanical performance of filaments was evaluated for application in sensors and actuators. The change of cross-sectional shape significantly influences mechanical properties of developed filaments which express their vulnerability during applied stresses in their life cycle.

Investigation of the Physical and Mechanical Properties of Raffia Vinifera Fibers along the Stem

ABSTRACT The study of the physical and mechanical properties of raffia vinifera fibers along the stem is examined in this work. In central Africa, these fibers are already being used by craftsmen in the field of textile and decoration. The cross-section of fibers is higher at the base of the stem and grows from the periphery toward the center on a transverse position. By the Archimedes method, the obtained bulk density was between 0.1288 g/cm3 and 0.2368 g/cm3 and in a transverse position, it increases from the center toward the periphery. The dynamic tensile tests were used to estimate the Young’s modulus that lies among 0.88 GPa and 7.9 GPa and the low values are at the base of the stem. The specific Young’s modulus was deduced and varied from 7.33 GPa/(g/cm3) and 66.00 GPa/(g/cm3). Finally, through the strain, the microfibril angle was found and it is oscillated from 29.81° to 48.65°.

Variance Analysis and Autocorrelation Function for 2D Fiber Lap Statistical Analysis

This chapter reports on the statistical analysis of 2D fiber lap using variance analy‐ sis and autocorrelation function. It begins with a short overview of the nonwoven processes showing the importance of lap and web formation. It then proceeds to de‐ scribe the theory of the ideal fiber web. The real defects are taken into account based on random irregularity, periodic irregularity, and compound irregularity. To conclude, the chapter highlights the efficiency of this theoretical approach and its application on 2D fibrous material.