This study deals with the effects of branching in some high polymers on viscosity behaviour and on the rela­tionship between intrinsic viscosity and molecular weight. First, the preparation of branched polymers by means of graft polymerization is described. Evidence for the occurrence of grafting, which would result in the growth of polystyrene branches on a min, or backbone, chain com­posed of polystyrene or a copolymer of styrene and li-vinyl-cyclohexene-1, is reviewed, Next, the design, construction, and calibration of a flexible light scattering photometer is described. The performance of this instrument is shown to bs adequate for the determination of the molecular weight and size, as well as the second virial coefficient, of a high polymer in solu­tion. Finally, properties of the graft polymers in solu­tion are compared, with the corresponding properties of linear polystyrene. The relationships found between intrin­sic viscosity and molecular weight, as well as the values obtained for the second virial coefficient, confirm the ex­istence of branching in the graft polymers. On the other hand, it is shown that the viscosity slope constant, Huggins' k', the of which, is often used as an indication of branching, is not affected significantly by the branching present in the graft polymers. / Thesis / Doctor of Philosophy (PhD)