The advantage of the preirradiation-induced graft polymerization method is that the homopolymerization of the monomer is depressed considerably and a high monomer utilization ratio can be obtained.33 Graft polymerization in emulsion is also more efficient than that in solution.26 The grafting method used in this study was designed with the advantages of both preirradiation and emulsion graft polymerization techniques, and the results indicate that this method would be promising for many applications.
Figure 2 shows the effect of the absorbed preirradiation dose of PVDF on DG of the PVDF-g-PGMA powder. Peroxides and hydroperoxides were intro- duced onto the PVDF by preirradiation in air.
When they were heated, the peroxides and hydroperoxides decomposed to free radicals, which initiated the po- lymerization. DG of the sample with an absorbed dose of 5 kGy approached zero, which was due to the existence of an inhibitor in the monomer that ter- minated the radicals because the agent was used without further purification. DG increased with increasing absorbed dose and became saturated when the absorbed dose exceeded 15 kGy.