Band 7, Heft 3

This article is a review which concerns microfibres, their classification, manufacturing methods, different fibre forms, general properties, as well as their various applications. A brief attitude related to economical problems and future prospects is presented.

The retained strength of wet spliced yarns can be controlled to some extent by suitable choices of certain factors related to the process. In order to understand how these variables influence the breaking force of wet spliced yarns, a central composite design was formulated and three variables - yarn count, the duration of air joining and the duration of water joining - were considered. Analysis of the results indicates that yarn count and length of splice contribute significantly to this mechanical property of wet sized spliced yarns. The duration of water joining, the duration of air joining of splice and the recipe size have a considerable effects.

The present work investigates the compressive properties of SBCF/PA12 commingled unidirectional composites manufactured by the hot compression moulding technique. Different forms of failure mechanism have been observed microscopically for different laminate thicknesses (6, 8, 10, and 12 layers). In addition, fibre-length distribution curves have been developed at failure points. Thus, failure explanations for the SBCF/PA 12 composite during the compression test could be developed, depending upon microscopic observations. Moreover, the effect of laminate thicknesses on compressive behaviour; stress, strain and modulus has been analysed. It was found that by increasing laminate thickness the compressive stress is decreased, the strain is increased and the modulus is decreased significantly.

A design methodology for the production of complex shapes through near net shape manufacturing is presented. The data was obtained by using a 3-D circular braiding machine that was designed and constructed by Prof. Dr. Aly El-Shiekh. Production of a braided truss shows the procedures required for producing right-angled and contoured parts, as well as the feasibility of producing such parts. The FRPC (Fibre-Reinforced Polymer Composites) truss reinforcement system was designed to simulate the conventional iron truss reinforcement system typically used in a concrete bridge deck. A technical comparison of FRPC (Fibre-Reinforced Polymer Composites) truss and steel truss is carried out with respect to weight, cost, compression and bending strength. Experimental results are presented to show how the nominal stresses (compression and bending) of 3-D braided composite trusses depend on truss height, truss width and truss angle, i.e. the number of working layers, number of yarns per each layer, braiding pattern and number of beats per cycle. It is shown that accurate mathematical models could be developed from the laboratory data to predict the compression and bending stresses of the truss from the basic braiding machine settings by using factorial design. The excellent fit of the predicted values with the measured values confirms that the mathematical models developed can be used to make accurate prediction of the compression and bending stresses from a knowledge of the truss specifications.

The moisture transmission behaviour of a clothing assembly plays a very important role in influencing its efficiency with respect to thermophysiological body comfort. This paper is in two parts. Part I deals with the processes involved in moisture transmission and the factors at play. Part II is concerned with selecting the measurement techniques which are of great importance in determining fabric factors that influence comfort. The instruments and methods used for testing purposes should adequately simulate the exact conditions for which the fabric will be used, in order to determine the effectiveness of that fabric for a particular wearing situation and environmental condition. The testing methods used and the apparatus developed by different researchers for determining moisture transmission through textiles by different mechanisms are discussed in this paper. Moreover, this part of the paper deals with the mathematical models of liquid and vapour transport through textile materials developed by several scientists in order to understand the exact phenomena involved and to predict the factors affecting the transmission under a particular condition.

We investigated the cytotoxicity of reactive dyes and dyed fabrics using human keratinocyte HaCaT cells in vitro. The HaCaT cells were exposed to three monochlortriazinyl dyes: yellow, red and blue with different concentrations. The HaCaT cells were also exposed to water extracts of dyed fabrics. After 72 hours exposure, the protein contents of the samples compared to the protein contents of non-exposed cells were measured. The level of protein content indicates the viability of the cells. The mean inhibitory concentration values (IC50) showed the dye concentration when the protein content of the sample was 50% of the protein content of the non-exposed cells. The mean inhibitory concentration values (IC20) when the protein content of the samples was 80% were also measured. The IC20 values show the limiting value of toxicity. The IC50 values show whether samples are clearly toxic. The IC50 value for the yellow dye was 237μg/ml and the IC20 value was 78μg/ml. The IC50 for the red dye was 155μg/ml: the red dye caused adverse effects under the lowest dye concentration (28μg/ml). The IC50 value for the blue dye was 278μg/ml and the IC20 value was 112μg/ml. Cotton fabrics dyed using these same three reactive dyes were extracted with water and the extracts were analysed using the HaCaT cell line. The viability of the cells was good, the protein content of the samples being over 80% compared to the non-exposed cells. The HaCaT cell test indicated the toxicity of pure dyes; the dyed fabrics had no adverse effect. The human keratinocyte HaCaT cells seem to be a useful tool for the study of the purity/toxicity of dyes and other substances applied to textiles.

We investigated the cytotoxicity of reactive dyes and dyed fabrics using an in vitro hepa-1 cytotoxicity test. Hepa-1-mouse cells were exposed to three monochlortriazinyl dyes: yellow, red and blue with different concentrations. The hepa-1-mouse cells were also exposed to water extracts of dyed fabrics. After 72 hours exposure, the viability of the cells was detected by measuring the protein content of the cells. The mean inhibitory concentration IC50, which shows the sample concentration when the protein content is 50%, was compared to the total protein content of the non-exposed cells. The inhibitory concentration IC20 value, which shows the sample concentration when the protein content is 80%, was also measured. The IC20 value shows the limiting value of low toxicity. The values measured showed high toxic effects of the dyes. The blue dye was shown to be the most toxic, although the red dye showed toxicity at the lowest concentrations. Wheras the pure dyes showed toxicity under low concentrations, the dyed fabrics showed no toxicity. The hepa-1 cytotoxicity test and the spermatozoa motility inhibition test supported each other, giving similar results. Both tests can be used when studying the toxicity of textile substances.