Band 5, Heft 1

This paper presents a method for improving the yarn-end preparation on a splicer by forming a loop outside the opening tube which assures gentle delivery of the yarn to the opening tube, as well as control of the yarn-end length which will be prepared. Twelve groups of yarns were selected and tested using the new technique and a standard splicer. The new technique for yarn-end preparation showed better results in comparison to the standard splicer, especially for high twisted and plied yarn.

Over the past century or so, determining the predictive models of yarn strength has been the subject of a number of investigations, because yarn strength is a principle component of yarn quality. The aim of these models is to enable the yarn strength to be predicted from the properties of its component fibres as well as other parameters. The development of predictive modelling of yarn strength is always significant both in theory and in practice. In this article, a review of various predictive models of yarn strength is presented.

Spider dragline silk is an extremely strong biopolymer and has unique combination of desirable mechanical properties. In the present paper dragline of Golden Nephila spider was studied for dimensional, structural, physical and tensile properties. The test results established significant variability in diameter and denier of dragline filaments. The filaments possessed nearly circular cross-section and were found to be sensitive to moisture. The draglines exhibited super contraction in water. It has high strength and large elongation to break (45.9 cN/tex and 38.7 %, respectively). X-ray crystallinity of 17.5 % was obtained. The fibres were also subjected to thermo- mechanical and dynamic mechanical analysis.

Microwave irradiation technique was used for the chemical modification and grafting of protein fibrous materials, such as domestic silk (Bombyx mori), tussah silk (Antheraea pernyi), and wool fibres. Epoxide compounds Denacol EX810 and EX313 reacted effectively with the protein substrates. As alkali catalysts, sodium hydroxide was more effective than sodium thiocyanate. The optimum concentration was 0.25 w%. Weight gain values up to 8% were attained with 10-15 min irradiation time at 200W power. Graftcopolymerisation of vinyl monomers onto protein fibres resulted in variable weight gains, depending on the kind of fibre, the grafting monomer used, and the concentration of the padding solution. For example, after grafting with iso-propyl methacrylate (IPMA), the weight gain of fibrous proteins took place in the following order: Bombyx mori silk > tussah silk > wool. Bombyx mori silk gained more weight with IPMA than with 2- hydroxyethyl methacrylate (HEMA) or methacrylamide (MAA). The weight gain of Bombyx mori silk with HEMA significantly increased when the initial monomer concentration was raised to 400% owf, reaching a maximum value of 40%. The tensile properties of the protein fibres grafted with IPMA, MAA, and HEMA remained unchanged or slightly improved compared to the reference fibres. Fibres modified with epoxides showed a drop in tensile performance. The surface morphology of fibres treated with epoxide compounds or graft-copolymerised with vinyl monomers was almost unaffected, with the exception of HEMA-grafted fibres, which showed the presence of homopolymer deposited onto the surface at a weight gain exceeding 20%.

This paper describes a quick prototyping unit for fibrous multifunctional structures which has been set-up at the University of Minho. This unit provides for fast development of technical samples for a variety of special applications, mainly in the areas of health and well-being, sports goods, personnel protection, techno-fashion, the civil construction and building industries, composite materials, and so on. The unit works systematically through the areas of conceptualisation, design and simulation, development, manufacturing and testing of technical and intelligent textile materials and structures, providing solutions for technical problems. New structures are developed for specific applications where special requirements are needed. It provides the best solution in terms of materials, structures, technologies and cost. The technologies involved include advanced CAD systems, FEA (finite element analyses), testing of mechanical properties, permeability, conductivity, microscopy, as well as smallscale- computer controlled manufacturing of yarns, nonwovens, wovens, warp & weft knits, braids and hybrid structures. Special finishings and surface treatments, coating and lamination are also possible. The unit is used for research, education and to provide services for companies in emerging markets for advanced textile materials. Examples of the novel products developed are provided.

Two kni:ed wool fabrics with the same cover factor, yarn count and twist were used our experiment. The only variable introduced was the mean diameter of the wools, 19.2 μm and 25.6 μm. The aim of the work was to evaluate the effect of proteolyHc enzyme treatment on the pilling behaviour of fabrics, and in parHcular on the yarn structure with different concentraHons of proteolyHc enzyme, and then the pilling behaviour was measured by using the pilling box test. The results obteined show that the proteolyHc enzyme, within given levels of concentraHon, improves the pilling behaviour of the fabrics.

The work presented in this paper concerns an investigation we have carried out into the water retention ability of activated carbon nonwovens manufactured from cellulose fibres. The precursor nonwovens manufactured by the spun-laced method were pyrolysed and carbonised at temperatures of 400°C, 600°C, and 800°C, and next activated at the temperature of 850°C. The kinetic curves of water sorption and the absorption parameters were assessed. The proper(es of the microporous structure of the fibres were determined on the basis of the nitrogen sorption isotherm. The activated nonwovens were characterised by an active internal surface of over 1000 m2/gl. As the result of activaton, the water absorption increased by over 2.5 (mes when compared with the absorption of precursor nonwovens. The tests carried out allowed us to state that water reten(on mainly depends on the physical and the chemical properties of the carbon surface, as well as on the content of great pores in the porous structure of the fibres. In turn, the surface properties depend on the processing temperature.

The paper presents a model of transverse deformation in a textile product consisting of two external layers combined with deformed elements in the middle layer. Transverse deformability of textiles is particularly significant for several-layer products, and is decisive for the utility properties of such products.