A study has been made on the irradiation induced grafting of MMA to PPE and cellulose subtrates in the presence of various solvents and Irgacure 819 photoinitiator, a new photoinitiator on the market at the commencement of this project. UV is the main irradiation source used. The grafting yields have been found to vary with parameters such as the subtrate types and thickness, MMA concentration, solvents used, Irgacure 819 concentration and UV doses. For the cellulose subtrate, good grafting yields were obtained only when solvents such as methanol and DMF were used. On the contrary, MMA could graft to PPE with or without solvents, although high grafting yields were achieved in the presence of methanol, DMF and other chlorinated solvents. The solvent effects on the grafting process of MMA to PPE and cellulose subtrates were attributed to the wetting and swelling effects by the solvents as well as the Trommsdorff effect. During the course of this study, a comparison in the performance between Irgacure 819 and other photoinitiators (PIs) was also carried out. A study was made of the UV radiation induced grafting of styrene to PPE subtrate with EP vinyl monomers and vinyl ethers as comonomers. The possibility of spontaneous polymerization of styrene/EP vinyl monomer mixtures under the influence of UV radiation was also investigated. Grafting yields were found to vary with the comonomer types and their concentrations, the presence or absence of solvents and additives such as Irgacure 819 photoinitiator, K185 cationic photoinitiator, mineral acids and CT complexes. In addition, the composition of grafted subtrates was studied by using the FT-IR spectroscopy technique / Doctor of Philosophy (PhD)