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No description available.

No description available.

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No description available.

The object of this work is to investigate the effect of loop length on the geometrical and more particularly on the physical and mechanical properties of the plain weft knitted fabrics. Two sets of fabrics were produced from 2/26s worsted yarn using knitting machines different in type and gauge. The first set was knitted from single yarn and the second from two-ends with a wide range of loop length. Both sets were given three different relaxation treatments, dry, wet- and full-relaxation. Dimensional measurements and geometrical parameters were determined and examined and the results show that for some fabrics there is some deviation from the results of other workers in this field. The study also involved measurements and tests of certain yarn properties which provided useful background information about this yarn and which might help to explain certain properties of the knitted fabrics. The yarn properties measured and tested were, twist, friction, flexural rigidity, tensile and elastic properties. Experimental results indicate that an increase in loop length leads to an increase in air permeability and percentage weight loss when the fabric subjected to abrasion. It is found that for two-end fabrics the percentage weight loss is non-linearly related to the loop length and this reflects the yarn arrangement within the structural unit cell. While there is not always a direct relation between the loop length and the fabric thickness, there is however, a proportional relationship between the parameter t/L and the cover factor K. In this investigation, the predicted tensile strength and extension at the point of break worked out on the geometrical basis when the fabric is extended in walewise and coursewise direction. Once more the fabric made from two-ends behaved differently when it was subjected to tensile and to repeated cycles of extension. Fabrics made from two-ends are stronger at break but have lower recovery than the fabrics made from single yarn. While there is a relationship between the total elastic recovery and the loop length for the fabric made from one-end, it appeared that it is difficult to find a systematic relationship between the total elastic recovery and the loop length for fabrics made from two-ends in both the dry- and fully-relaxed state due to the involvement of the yarn arrangement within the structural unit cell of the fabric. In addition to the pattern of yarn arrangement within the structural unit cell in the two-end fabric, there is relative yarn movement which may affect the dimensions of the cell.

A multi-station flex fatigue tester has been developed, allowing a wide range of environmental settings. A detailed study of fatigue behaviour under increasing temperature and humidity is made. In general, an upward trend in fatigue life of all the polymers tested is recorded with increasing temperature and humidity. Scanning electron microscope studies of unbroken samples under specific conditions revealed a central split in the fibre at the point of flexure. Partially fatigued fibres are tensile tested for their remaining strength and their fracture morphologies examined. Finally, a theoretical explanation of the apparent cause of increase in fatigue life is given in relation to the development of the central crack.

No description available.

The frictional (fricative) properties of some 23 fabrics are reported. These properties include frictional resistance, amplitude of resistance, number of peaks, difference between static and kinetic frictional resistance in addition to coefficients of friction, all determined by trace analysis. Some assessments of properties of subjective handle likely to be related to objective measurements are also reported, for example fabric smoothness or roughness. The work is reported in series of case studies. Firstly a general survey is made in order to demonstrate the likely range of properties, and the effects of experimental variables such as pressure, velocity of sliding, nature of sled surface, number of traverses. Secondly, a series of plain weave fabrics is used whose density of consolidation is systematically increased by increasing the picks per unit distance. Thirdly, the fricative resistance of a group of woven pile (cord) fabrics is measured with the purpose of demonstrating the sensitivity and selectivity of methods of measurement which include a roller, stylus, lateral air flow as well as the conventional fabric covered sled. Fourthly, a series of knitted fabrics is used whose fibre content and construction differs systematically. For example they include cotton, wool and acrylic fibres, and are constructed as plain knit or rib knit. Fifthly, the effects of various physical and chemical modifications of knitted and woven fabrics are illustrated. These treatements include those designed to increase fricttional resistance such as starch and silica, or reduce friction such as polyethylene glycol. By these case studies the relative influence of fibre content, fabric structure and also finishing treatments on fabric friction and handle are demonstrated.