The present work deals with the development of comprehensive mechanical models to predict the mechanical properties of woven fabric structures, namely the tensile, bending and compression behaviour. All the models are based on the Rayleigh-Ritz energy method, which allows handling non-linear mechanical properties of constituent yarns while producing computationally efficient algorithms. The models incorporate all modes of deformation, i.e., yarn elongation, yarn bending and yarn compression. An effort has been made to make the models more general by considering generalised geometry with adequate degrees of freedom to represent the yarn path under all deformed configurations. A new geometric model based on polynomial geometry has been developed and it has been shown that the mechanical models based on the new geometry closely simulate fabric tensile behaviour. The model developed for plain woven fabric has been generalised to predict the tensile behaviour of regular non-plain woven fabrics by specifying the number of crossovers and number of floats in a weave repeat and it was shown to give consistent predictions for different fabric structures. The pure bending behaviour of plain woven fabrics has been studied considering both a single 5th degree polynomial and a piecewise Hermite polynomial geometry. The deformed state is obtained using the principle of stationary potential energy without invoking work-energy theorem and hence they predict the complete moment-curvature relationship of fabric. The compression behaviour of single fabric has been studied by characterising the yam compression behaviour using an inverse method and the compression behaviour of double fabrics has also been modelled. The solution of models using non-linear programming constrained minimisation techniques has been demonstrated using readily available optimisation software. The models have been validated against the data reported in the literature along with the experimental results of glass fabrics. The predictions of models have also been compared against the results of Finite Element Analysis (FEA) using the general purpose FEA software ABAQUS. The compaction of fabric between two rigid plates has been simulated using 3D FEA. The geometry of yarn path derived from the mechanical models has been used to construct 3D FEA models for studying the micro-mechanical behaviour of plain woven fabric composites.

Digital image processing techniques have been used to analyse structural and geometrical properties of nonwoven fabrics. The development of automatic measurement methods for pore size and fibre orientation distribution has been the main focus. The measurement algorithms, together with some preliminary testing results, are discussed in this thesis. Pore size distribution is a crucial design criterion in many industrial, particularly geotechnical applications of textiles and an important product specification parameter. The orientation of fibres in nonwoven fabrics is one of the determinant factors of the physical behaviour of the fabrics. Reviews of literature have indicated that the existing methods of determination of these two properties are laborious, time consuming and, in some cases, controversial. The automatic methods described herein enable accurate evaluation of pore sizes and fibre orientation to be achieved far more quickly and economically. The system has the advantage of being fully programmable, thus will be available for other work. A review of the work was presented to the UMIST Nonwoven Conference, June 1988.

The dispersion of clays at the nanometer level is known to induce a significant improvement in mechanical properties, flame resistance and barrier properties, compared with pure polymer. Application of ultrasound in polymer processing can be used to improve additive dispersion in polymer melts and solutions but may also initiate chemical reactions and modify the rheological and mechanical properties. This thesis studies the effects of applying ultrasound to the molten fibre-forming polymers, polypropylene (PP) and polyamide 6 (PA6) containing nanoclay and flame retardant additives in order to assess whether improved dispersion generates improved flame retardant properties of derived fabrics.

The research work was concened with the design of tension compensators for spinning-winding machines for the purposes of reducing winding tension variation during high speed cone winding. Initially, the research was directed to investigating the 'winding error', i.e. the difference between yarn supply and demand, which was the main cause of winding tension variation. Mathematical models were established to analyse the winding velocity variation and yarn path length variation. Several methods have been investigated to reduce winding tension variation and to develop tension compensators. These include using a servo motor to keep constant winding velocity and using a curved distribution bar to keep constant path length. Two promising tension compensators were selected for detailed investigation. they were a mechanical compensator and a mechatronic compensator. Based on the analysis of 'winding error', A multiple bar mechanism was devised, analysed and optimised to provide tension compensation. Further consideration has been given to a microprocessor controlled mechanism, that works according to predetermined look-up tables and sensor signals to reduce winding tension variation. The computer simulation of yarn winding process, the software design for the optimisation of mechanical compensator and the control of mechatronic compensator, and the results of winding tension experimentation are also presented in the thesis.

The objective of the Engineering Doctorate project was the development of a continuous yam dyeing system which could meet the needs of a changing textile industry. Through an examination of the changes in the industry, it was found that the system must incorporate waste minimisation principles, be flexible and responsive to the demands of the fashion industry and provide the yam dyer with short lead times. Two yam processing systems were identified and investigated to determine whether they could be used to fulfil the aims of the project. The first system was based on the Fibre 'M' Yam Texturing and Dyeing process previously developed at UMIST. The second was a new development referred to as the Sealed Applicator Device (SAD). It had been shown in the past that the Fibre 'M' based system could simultaneously texture and dye polyester yam to a relatively high standard of fixation and bulk. However, through the process investigation presented here it was found that the system lacked flexibility, ease of use and, in addition, its environmental impact could be considerable. The investigation of the SAD process proved to be more fruitful. It was found that the SAD process could be used to impregnate single ends of yam with liquor to a high degree of accuracy and control. Laboratory trials sho~ed that the SAD system could be used to impregnate worsted yam with dye liquor levelly at yam speeds up to 500 m1min at liquor to goods ratios as low as 0.3 : 1. Also it was shown that the SAD system could be used as a high speed yam washing device as well as a yam drying device. Through a combination of the impregnation, washing and drying capabilities of the SAD process, in conjunction with an autoclave stage, it was demonstrated that the SAD process could be used to continuously dye, wash and dry yams at high speed to commercial standards of penetration, levelness and fastness. The potential savings for a yam dyer through the use of the SAD system were explored. It was also shown, through commercial trials, that the SAD system could be used as an integral part of a simultaneous yam folding, setting, conditioning and lubricating process for worsted yams. Comparable levels of setting, conditioning and lubricating to the industry standard were achieved using the SAD process, with the potential for considerable saving for the spinner.

This investigation is concerned with the relation between the structure of nonwoven fabrics and their physical properties. The theoretical approach is based on the behaviour of the fibre network in the fabric, This affords a method of predicting the stressstrain properties of the nonwoven. For a complete explanation of the nonwoven properties it is found that the influence of the binder matrix must be taken into account. Experiments are described which were conducted on laboratory-made fabrics and on model systems of single fibres bonded together. These gave an indication of the manner in which the binder contributes towards the fabric properties. The nonwoven fabric is introduced in Chapter I with a brief description of the commercial methods of manufacture and the current applications. There follows a review of the previous publications in this field. In Chapter 2 a simple mathematical treatment of the behaviour of the fibre network in the nonwoven is outlined. A special solution is afforded for the caso of deformation under uniaxial tension. The theory results in a method of predicting the stressstrain curve of the fabric from the deformation of individual fibre segments. It requires a knowledge of the fibre stress-strain properties and the arrangement of the fibres in the fabric. In the last part of this chapter the lateral strain in a fabric under uniaxial tension is considered. Measured values of the Poisson's ratio of several fabrics are compared with values calculated from the geometrical behaviour of simulated ideal networks , Chapter 3 is concerned with the application of the fibre network theory to commercial fabrics. The equations relating the stress in a fabric at any strain were programmed for calculation on an electronic computer. This allowed the summation of the stress in a large number of individual fibre segments to be carried out, using values of the parameters measured on the test fabrics. The results of the computation are compared ,·the those obtained from tensile tests on the fabrics. These demonstrate how the behaviour of the fibre network influences that of the fabric and indicate that the behaviour of the binder matrix must be introduced for a complete explanation of the fabric behaviour at high strains • .An experimental investigation designed to assess the effect of the binder on the physical properties of the nonwoven is described in Chapters 4 and 5. In Chapter 4 the production of special fabrics in the laboratory is outlined, They were constructed with varying binder contents and also the binder stiffness was varied. It was shown that an increase in either binder content or binder stiffness resulted in an increase in both the fabric tensile strength and initial modulus. The results were compared with those from fabrics made by linking the fibre network with a fibre solvent; the latter method of bonding resulted in a stiffer structure •Fabrics with varying binder contents were also made by adding specific amounts of binder to a commercial fabric and the tensile properties of these fabrics were compared with those predicted by the fibre network theory. A study of the behaviour of fibre-binder systems was carried out by bonding single fibres together and carrying out tensile tests on th8se model systems. These are described in Chapter 5. It is concluded that a system of two fibres linked by a small amount of binder will behave as if it consisted of fibre only, unless there is sufficient binder between the fibres, in which case the initial modulus is lowered, or unless the size of the bond is too small, in which case fibre slippage occurs. In the concluding chapter, Chapter 6, the relevance of the theoretical treatment and the experimental studies of binder behaviour to the nonwoven fabric properties is indicated. The combination of these two aspects of the investigation has been shown to provide an increased understanding of the behaviour of the nonwoven, and has demonstrated how future research may proceed.

The aim of this project was to design, produce and assess multilayer fabrics with crosslinks or stitches between the individual layers so that the interlaminar shear properties of the composite panels reinforced with these fabrics would be improved. In fact, 12 fabric variants based on a 2-layer a-end satin fabric (with a more number 3Up) were produced on a 4x1 SAURER 100W Shuttleloom, which was modified in order to weave these fabrics. 3-D cellulorr fabrics with novel triangular cores were also woven on this shuttleloom. All of the 2-layer a-end satin fabric variants (including one non-stitched (weave No.9); five weft stitched (weave No.s 32,33,19,34,25); three warp stitched (weave No.s 36,37,29) ; and four weft and warp stitched fabrics (weaves Nos. 35,38,39,40) were assessed for their mechanical performance, particularly in Tensile and Interlaminar shear deformations. A geometrical model, "MAMCA" ("Major and Minor Circular Arc") model, was proposed in order to describe the yarn paths (warp and weft) in all the above fabric variants. using this model ("MAMCA"), the average breaking load of warp and the maximum initial angle between the warp yarn and the fabric axis (ximax.warp)' the theoretical breaking load along the warp direction was estimated for all 13 fabric variants tested. The theoretical values of the breaking load of the above fabric variants in the warp direction, were compared to the Experimental values obtained from Tensile strip strength Tests. There was a reasonable degree of agreement between these two sets of breaking load values. Thus, this method could be used to predict the breaking load of such fabrics in the appropriate loading direction.

The object of the work was to develop the use of high-pressure steam in order to replace air in air-jets in the production of intermingled yarns, particularly for sewmg threads. The thesis discusses the development of air-jet texturing! intermingling and analysis of the process by earlier workers. Differences between steam-flow and air-flow through jets are discussed. The effects of process parameters on steam-jet intermingling and comparisons of steam-jet intermingled yarns and air-jet intermingled yarns have been studied. The results show that steam-jet intermingled yarn has higher strength, higher elongation, higher loop stability and lower boiling water shrinkage than air-jet intermingled yarn. Core-yarn wetting does not have a significant effect on the steam-jet intermingling process and intermingled yarn properties. Elimination of the wetting system reduces the production cost of steam-jet compared to air-jet. Steam-jet intermingled yarn needs less energy to heat-set after intermingling, as it has been partially heat-set by steam during intermingling. Sewing threads were made from steam-jet intermingled yarns and assessed using industrial sewing specifications. The sewing threads were also subjected to commercial trials. Sewing test results show that steam-jet intermingled sewing thread meets commercial levels of performance. Preliminary investigations revealed that high-pressure water could also be used in intermingling as a replacement of air or steam. It was found that lower core-yarn overfeeds, such as 2.9 %, can be used and therefore higher strength of intermingled yarn could be achieved. Turbulence in water was improved by designing a jet so as to suck air by water through a capillary from the outside atmosphere.

The wet fibrillation behaviour of Tencel yams was investigated using a wet yam-onyam abrasion system. The effect of crosslinking using reactive dyes or colourless reagents was to improve the wet fibrillation performance by improving fibrillar cohesion. The effect of a range of typical wet treatments were evaluated and found to decrease the beneficial cross linking mechanism. Increasing the temperature of the testing bath increased the polymer flexibility giving rise to a decrease in wet abrasion. Nevertheless the wet abrasion of crosslinked derivatives was still better than that of the original Tencel. The role of swelling and dehydratingldeswelling agents on Tencel yams was examined and found to have significant effects. The wet abrasion system was combined with the surface analytical technique X-Ray Photoelectron Spectroscopy (XPS) to probe the nature of Tencel surface modifications and their possible effects on colour care and wet abrasion performance. Using elemental indicators such as N(ls) and S(2p) photoelectron peaks the presence of dyes and cationic fixing agents was demonstrated at the fibre surface. It was also demonstrated that the durability of a direct dye to washing was significantly improved by Matexil FC-ER. The nature of the 'cationic' Matexil FC-ER was characterised and the substantivity of the charged and uncharged components determined. Differences in the effect of cationic fixing agents on the wet abrasion of Tencel was established. The effect of perborate and non-perborate based detergent formulations on reactive and sulphur dyed Tencel was evaluated and differences in oxidative behaviour demonstrated. In particular, the increased oxidation of disulphide bonds in the sulphur dye was evident with perborate-based treatments. The role of specific surface (plasma treatments) and bulk modifications on the wet abrasion performance of Tencel were examined although few beneficial effects demonstrated.

The application of softeners to textile is known to enhance the fabric handle. In this study the potential for novel softeners, commonly used in the cosmetic industries, has been investigated with a view to improving the textile handle and also imparting a protective effect against wear abrasion. To assess Cotton and Tencel fabric handle and wear strength objectively, the Kawabata Evaluation System for Fabrics (KES-F) and the Martindale Flat Abrasion instrument have been utilised. In addition a novel Y am-on-Y am abrasion system has been developed to assess dry and wet abrasion. Both beneficial and detrimental effects have been demonstrated on the cellulosic substrates by the application of softeners and the performance behaviour has been discussed. As part of the project an experimental rinse conditioner formulation for domestic laundering was evaluated and its effectiveness in comparison to a standard formulation studied. However, little benefit was observed in terms of fabric handle and the ineffective behaviour investigated using the surface sensitive analytical technique, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). ToF-SIMS was able to characterise a range of softeners demonstrate their substantivity to the cellulosic substrate and the preferential adsorption of a cationic imidazoline softener at the fibre surface. The Y am-on-Y am abrasion system has been used successfully to probe the wet fibrillation of reneel yams and has the appropriate sensitivity and reproducibility to differentiate between fibre erosslinking regions and non-crosslinking reagents. The influence of reactive dyes, crease resist finishes and novel colourless cross linking has been investigated and the behaviour related to the level of fibre crosslinking. The affect of softeners on abrasion performance has also been evaluated and their affects on wet and dry yam abrasion established.