Band 6, Heft 3

We introduce a new concept of ring-spinning. The model system built on the basis of this concept is capable of producing yarns at a production rate of up to 4 times that of the traditional ring-spinning system. This is a direct result of a ring rotational speed of up to 40,000 rpm. This new concept is termed ‘magnetic spinning’, and it principally consists of a lightweight rotor suspended magnetically inside a fixed stator; the rotor can spin freely inside the stator. The stator is equipped with four magnetic actuators that always keep the rotor in its central position. The rotor in this configuration replaces the ring and traveller in the traditional spinning system. The system’s concept and control analysis are discussed in this paper.

The effect of lap hank, card draft, draft/doublings and drafts at speed frame, ring frame, rotor and air-jet on packing density parameters were analysed using the Taguchi method. The trends of change in packing density with process variables are opposite to those of the yarn diameter and helix angle of the ring, rotor and air-jet yarns studied. The packing density is found to be the highest in air-jet yarn and the lowest in rotor yarn. An increase in draft in the air-jet and a decrease in the rotor spinner increases the packing density of the respective yarns.

High-modulus and high-tenacity polypropylene fibres were prepared by drawing as-spun filaments on a heater with a temperature gradient. The results on two different MFI PP show that the fibre properties are significantly affected by the temperature profiles at the final stage of drawing on a gradient heater. High crystal perfection and crystallinity at very high draw ratios have been obtained for the gradient drawn fibres. The gradient drawn filaments showed superior mechanical properties when compared to filaments drawn over a constant temperature heater. Fibres with an initial modulus of 16.4 GPa and tenacity of 875 MPa were obtained in the process. The molecular weight of the parent material significantly influenced the mechanical properties of the material. High molecular-weight (low MFI - Melt Flow Index) materials are characterised by comparatively lower modulus but higher tenacity values. High draw ratios were possible for the higher MFI samples, leading to more orientation and modulus.

The optimum-size add-on for corespun Dref yarns and 100% cotton Dref yarns was studied, and was found to be approximately 15%. A rich size recipe consisting of acrylic at high add-on further improves the weavability, although it fails to bring the weaving potential to a par with that of ring- and rotor-yarns sized with normal modified starch at low add-on.

In recent times, a wide range of textile materials has been used as thermal insulators in many industrial applications. The thermal insulating properties of textile fabrics depend on their thermal conductivity, density, thickness and thermal emission characteristics. Experiments have been made with the aim of studying heat transfer by conduction through the different types of fabrics used as thermal insulators. 100% polyester and 100% polypropylene nonwoven fabrics are used in this work as case studies. The temperature variation through the selected fabrics is measured under different operating parameters such as densities and inlet temperature. The thermal response and behaviour for the selected fabrics used in this work as thermal insulators are illustrated. The relationship between the thermal conductivity and material density of the selected fabrics is studied. Polyester fabric has higher thermal resistance and specific heat resistance than polypropylene. Fabric thickness has a significant effect on the fabric temperature variations. The results of ?[Anova-two way measurements] are presented for 100% polyester and 100% polypropylene nonwoven fabrics. The temperature variation of the fabric increased with the testing time, and also decreased with the increase of fabric weight up to a certain limit beyond its optimum level. The results show that the selected nonwoven fabrics are suitable for usage as thermal insulators.

In this article, a method for assessing the quality of now-widespread neuron models is presented. Attention has been paid to the significance of analysing individual input quantities in the model constructed. Then, the parameters which are quantitative measures of the neural model’s quality have to be specified. The need for structural verification of the network is stressed, which is the basis for stating that the neural model obtained has been well matched with the investigation results. The assessment of the neural model’s quality has been shown, using a model of the flow characteristics of fabrics as an example.

Non-absorbable sutures are monofilaments or braided structures generally made of polyamide, polyester or polypropylene. The success of a suture is widely linked to its mechanical performance features, such as tensile strength and dimensional stability. We introduced an additional treatment in the manufacture of non-absorbable braided sutures made of polyester. This treatment is based on heat setting of the textile structure by using textile-industry stabilisstabilisation techniques. Boiling water, saturated vapour and dry heat have been tested to stabilise a braided polyester suture. The three techniques involved longitudinal and transversal shrinkages. Heat setting with saturated vapour, and especially with dry heat, increased the breaking strength of the textile structure.

Carboxymethyl cellulose (CMC) is a water-soluble cellulose derivative widely used in textile preparations, especially for the application of sizes, which are removed shortly after the weaving process. In this paper, a strategy is given for using CMC as an anionical polymeric modifier of cotton surfaces with permanent character-imparting stable properties, such as after cationic dyeing, durable press properties and polyelectrolyte layer formation, without the use of dangerous chemicals like chloroacetic acid or salts. Thus CMC was fixed onto cotton by using CMC and Na-hydroxydichlorotriazine as an anchoring chemical. The fabric samples before and after finishing were monitored for polyelectrolyte titration values, wet and dry crease recovery angle, and K/S values after fixation of cationic dyestuff.

In this study, the toxicity of reactive dyes and dyed fabrics was investigated using spermatozoa cells in vitro. Boar semen was exposed to different concentrations of monochlorotriazinyl dyes: yellow, red and blue. The spermatozoa cells were also exposed to extracts of dyed fabrics. After 24 and 72 hours respectively, the viability of the cells was evaluated by microscopy. The mean inhibitor concentrations IC50, showing the concentration of the dye when half of the cells are dead compared to the control sample, were calculated from the viability values. After 24 hours’ exposure, the IC50 value calculated for the yellow dye was 135μg/ml, and after 72 hours 60μg/ml. The IC50 value for the red dye was 124μg/ml after 24 hours, and 46μg/ml after 72 hours. The IC50 value for the blue dye after 24 hours was 127μg/ml. After 72 hours, the blue dye caused high toxicity: more than half the cells were dead. Cotton fabrics dyed using these three reactive dyestuffs were extracted by water and analysed by the spermatozoa motility inhibition test. The viability of the cells when exposed to fabric extracts was good. However, after 72 hours’ exposure, the standard deviation and coefficient of variation values for cell viability of fabric extracts were large. The spermatozoa inhibition test indicated the toxicity of pure dyes, the dyed fabrics having no adverse effects. The spermatozoa test seems to be useful when screening different substances and when used in addition to other tests. The spermatozoa motility inhibition test can be used for textile material studies.