Surface graft polymerization high-energy radiation

High-energy radiation such as ultraviolet (UV) radiation, X-rays, y rays and electron beams can initiate polymerisation. Radicals formed into polymeric materials during sterilisation by such radiation have a long life, especially in the bulk of the material, and can initiate new polymerisation. Such an initiation process has been used widely to modify polymeric surfaces by grafting another polymer. 

Graft copolymerization is the most effective method utilized in the chemical modification of natural fibers. According to Gassan et al. [99], the reaction is initiated by free radicals on the fiber surface. Ionization polymerization of fibers is carried out in an aqueous solution, followed by exposure to a high-energy radiation. Fiber molecule cracks and radicals are subsequently formed. Next, the radical sites of the fiber are treated with a suitable solution compatible with a polymer such as vinyl monomer, acrylonitrile, methyl methacrylate, or polystyrene. Finally, this leads to the formation of a graft copolymer, which possesses fiber and graft polymer characteristics. 

High-energy radiation grafting is a powerful method that is used to alter or improve the surface properties of polymeric materials [162]. The principal points of the process were described in Section 5.2.3, and several applications are listed in Table 5.13. 

Radiation grafting [83, 84, 85, 86, 87, 88, 89] is a very versatile and widely used technique by which surface properties of almost all polymers can be tailored through the choice of different functional monomers. It covers potential applications of industrial interest and particularly for achieving desired chemical and physical properties of polymeric materials. In this method, the most commonly used radiation sources are high-energy electrons, y-radiation, X-rays, U.V.-Vis radiation and, more recently, pulsed laser [90], infrared [91], microwave [92] and ultrasonic radiation [93]. Grafting is performed either by pre-irradiation or simultaneous irradiation techniques [94, 95]. In the former technique, free radicals are trapped in the inert atmosphere in the polymer matrix and later on the monomer is introduced into... 

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