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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.

My work is a collection of narratives. Each one is the unfolding of the story of a person or thing. Several pieces are made up of objects that tell the story of their owners, giving clues to their lifestyles and experiences. I am interested in the story behind the things and people that I come across on a daily basis. For instance, what was housed in the drawers of the dresser I found in a thrift shop? Who drank from the milk bottle I now use as a vase? If I see a discarded toy on the street, I wonder what events led up to its abandonment. The way in which all of the represented objects and people are linked is left ambiguous, so that the viewer can create their own narrative. The more abstracted pieces are close-ups of objects. These pieces document the wearing away or fraying of something, telling many stories over several years, possibly portraying a wall that has been painted over many times, causing it to flake, or a shirt that has been worn to the point of disrepair.

Ce travail de thèse se place dans le contexte de la valorisation du polylactide (PLA), un polymère issu de ressources renouvelables, dans le secteur des textiles techniques. Ainsi, de nouveaux filaments nanocomposites ont été élaborés par filage en voie fondue suivi d’un étirage, un procédé facile à mettre en œuvre en milieu industriel et exempt d’utilisation de solvants. Les charges utilisées sont les nanoparticules d’oxyde de zinc (ZnO) et d’argent (Ag) largement utilisées pour apporter des propriétés antibactériennes aux matériaux. De plus, ils sont non toxiques pour les cellules mammifères et assez stables thermiquement pour convenir au procédé de filage en voie fondue. En général les oxydes métalliques (ici le ZnO) sont utilisés pour recycler le PLA par dépolymérisation. Lors de cette étude, différentes techniques ont été utilisées pour le disperser finement dans le PLA et produire des filaments avec une moindre dégradation des propriétés thermo-mécaniques. Ces filaments ont ensuite été utilisés pour réaliser des étoffes maillées qui ont présenté de très bonnes propriétés antibactériennes. Les nanoparticules d’argent à très faible quantité (environ 0,1%) dans le nanocomposites apportent également d’excellentes propriétés antibactériennes. L’incorporation dans le PLA du mélange des deux types de charges (à faible quantité) a conduit à une amélioration significative des propriétés antibactériennes des tricots et ceci après plusieurs lavages. Enfin lors de cette étude, une contribution a été apportée sur l’explication du mécanisme antibactérien du ZnO qui est encore en discussion dans la littérature dans le cas de nos nanocomposites. / The objective of this thesis is to valuate polylactide (PLA), a polymer from renewable resources through technical textiles. So new PLA nanocomposite filaments were produced using melt spinning device. This process is solvent free and easy to implement in industry.The fillers used are nanoparticles of zinc oxide (ZnO) and silver (Ag) widely used to provide antibacterial activities to materials and are non-toxic for mammalian cells. Moreover they are thermally stable and suit melt spinning process. Generally metallic oxides (here ZnO) have been used for the recycling of polylactide (PLA) via catalyzed unzipping depolymerization. In this contribution, we used different way to finely dispersed ZnO in PLA and produced filaments with less degradation of thermal and mechanical properties. These filaments are used to produce knitted fabrics with very good antibacterial properties. Silver nanoparticles has also impart excellent antibacterial properties to knitted fabrics with very small amount (around 0,1%). The incorporation of both nanofillers in the PLA improves significantly antibacterial properties of knitted fabrics and allows to obtain very good antibacterial properties even after multiple launderings. Finally, during this study, a contribution was made on the elucidation of the mechanism of antibacterial activity of ZnO still under discussion in the literature in the case our nanocomposite textiles.

Diss.--Köln, 2000. / Bibliogr. p. 245-259.

Thèse : Lettres : Lyon II : 1976. / Titre provenant de l'écran-titre. Bibliogr.