On absorbing the UV light, the photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone is known to produce benzoyl and isopropanol radicals by homolytic cleavage of the C−C bonds.Consequently, the UV prevulcanization initiated by the photoinitiator used can only occur through a process involving free radicals. The proposed mechanism for the prevulcanization is shown in Figure 6.