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.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:601467 |
| Date | January 1965 |
| Creators | Newton, Alan |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0018 seconds