Advantages of radiation-induced grafting

A radiation-induced grafting technique has been commercialized for the production of ion-exchange membranes as separators of batteries, hydrophilized hollow-fiber membranes for microfiltration of protein solutions, and ion-exchange nonwoven fabric for the removal of trace amounts of gases from ultraclean rooms [1,2]. 

Grafting enables role allotment in polymeric materials. The role of the trunk polymer is to provide an appropriate practical shape and to maintain chemical-resistant stability, while the branch polymer exhibits various functionalities such as separation and catalytic reaction. 

Excitation sources for the production of radicals in grafting include chemicals, light, plasma, and radiation. Radiation-induced graft polymerization is superior to other grafting techniques because the high density of electron beams and gamma rays can create a large amount of radicals of arbitrary shapes of the p olymer, such as a hollow fiber [2-41], nonwoven fabric [42] and film [43- ], and the quality of the polymer, such as polyethylene [2-41], polytetrafluoroethylene [42], and cellulose [55]. 

Radiation-induced graft polymerization can be classified into two techniques in terms of irradiation opportunity (1) simultaneous grafting, i.e., the mixture of a trunk polymer and a monomer is irradiated, and (2) preirradiation grafting, i.e., a trunk polymer is previously irradiated and then brought into contact with the monomer [56]. From a practical viewpoint, the preirradiation technique is preferable because of the negligible formation of homopolymers and easier control of the degree of polymerization. 

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