Radiation Curing of Thermosetting-Thermoplastic Blends as Matrices for Structural Carbon Fibre Composites

Abstract

Radiation processing indicates all the processes based on the use of ionizing radiation that cause chemical changes in the matter. Practical application of radiation processing have been evolved since the introduction of this technology nearly fifty years ago. The earliest developments are represented by the sterilization of disposable medical products, preservation of food and crosslinking of plastic materials, while the curing of monomeric coatings was developed somewhat later (Woods, 2000; Cleland et al. 2003). In the last years the use of these and other processes has grown more and more and they are widely practiced today to produce heat–shrinkable plastic films for packaging foods or insulation on electrical wires and jackets on multi-conductor cables in order to increase heat tolerance and to improve the resistance to abrasion and solvents. Other important applications include the reduction of the molecular weight by scissoring of polymers, the grafting of monomers into polymers in order to modify their surface properties and the curing of fibrereinforced polymer composite materials, whose main applications are in automotive and aeronautic/aerospace industries (Clough, 2001; Singh et al. 1996; Lopata et al. 1999; Goodman & Palmese, 2002; Jhonson, 2006; Berejka, 2010). Due to its behaviour regarding the possibility to involve very small particles, like electrons or heavy ions, radiation processing is the ideal way to produce nano-structured systems. Different examples are reported in literature, such as nano-litography devices (Woods, 2000) and nano-hydrogels especially in the biomedical area (Singh & Kuma, 2008; Chmielewski, 2010). The radiation sources generally used in radiation processing applications can be divided into two main groups, that one regarding the use of natural or artificial isotopes and the other one in which particle accelerators are employed. In the first group artificial radioisotopes, like Cobalt-60 and Cesium-137, are included and the second group comprises electron accelerators, accelerators for the production of positive ions and x-ray generators (Woods & Pikaev, 1990; Spinks & Woods, 1990). Currently the most widely used sources of ionizing radiations in the industrial processes are Cobalt-60 and electron accelerators.