Fabric reinforced or textile composites are increasingly used in aerospace, automotive, naval and other applications. They are convenient material forms providing adequate stiffness and strength in many structures. In such applications they are subjected to three-dimensional states of stress coupled with hydro-thermal effects. Assuming that a composite material is a complex structure it is obvious that is hard to describe all its properties in terms of its parts properties. The properties of the composite depend not only on the properties of the components but on quality and nature of the interface between the components and its properties. As reinforcement two types of fiber fabric were used; first one is a simple type fabric of untwisted tows of carbon filaments while the second one is also simple type but as yarn and fill are used alternately untwisted tows of carbon and aramide filaments. There were some problems to be solved before molding: fabric stability during handling, cutting, imbuing the carbon and aramide tows are slipping one on each other leading to fabric defects; generally the epoxy systems do not adhere to the carbon fiber; in order to obtain a valuable material the nature of interface must be the same for polymer-carbon fiber and polymer aramide fiber. In order to solve these problems the two fabrics were covered (by spraying) with a thin film of PNB rubber. Into the rubber solution were also dispersed small amounts of clay (to create a better interface) and carbon black (to improve the electrical conductivity). The rubber presence solves the fabric stability problem; ensures the same type of interface between fibers and polymer matrix; ensures a more elastic interface between fibers and polymer matrix. This treatment induces modification on tensile behavior of fabrics. This study is about mechanical evaluation of such fabrics.

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