Textile performance, mechanics Structural properties

The use of Kevlar has been confined to specialised applications 98), where high mechanical performance and lightweight properties are essential, because of its present relatively high cost compared with conventional textile materials. These applications can be conveniently divided into two main categories, one where the fibres alone form the final product such as in cables and fabrics and the other where they act as reinforcing elements for the production of composite structures. 

High performance polymer fibers (HPPF) have excellent mechanical properties compared to traditional textile fibers such as nylon. The typical HPPFs are aramid and polyethylene fibers (6). Aramid is a generic name for a class of aromatic polyamide fibers, most of which are varieties of poly(p-pheny-lene terephthalamide). Kevlar is the trade name of the varieties of aramid polymers introduced conunercially by Dupont. The molecules in the fibers of these materials are oriented in the axial direction. Poly(p-phenylene terephthalamide) is a rigid molecule with the following structure ... 

Because textile materials are lightweight, flexible and strong polymers and biological tissues are themselves fibrous polymers, with very similar dimensional, physical and mechanical properties, they have found numerous applications as bioimplants. From their use as sutures and ligatures many thousands of years ago, to hernia repair meshes and vascular grafts in the present century, textiles continue to be explored for use in newer and better performing medical products. The currently available implants can be categorized as one-, two- or three-dimensional structures. 

During the initial stages of biotextile product development many in vitro and in vivo tests are performed to assess the key parameters of the implantable device, such as the chemical composition of the material, the level of surface contamination, the design of the textile structure, the initial mechanical properties, the thrombogenicity (the rate of blood clot formation) and... 

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