1. Investigations of styrene polymerized in wood using ionizing radiation as the chain initiator indicate that property improvements are of the same order as for thermally initiated polymerization. 2. Free radicals have been detected in irradiated cellulose, Dioxane lignin, Spruce Periodate lignin and Beaun’s “Isolated Native Lignin” as well as in wood subjected to radiation. Consequently, wood radical identification is not possible. 3. Analysis of radical concentrations and decay suggest the presence of one or more decaying radical species in irradiated wood. The persistent maximum in radical concentration found corresponds to one or two unique radical sites per molecule; possibly the terminal hydroxyl group. 4. Results suggest that in the grafting reaction the initiation is a direct radical-monomer couple and does not involve decomposing peroxides. / Thesis / Master of Engineering (ME)