Absorption spectroscopy has been utilized to characterize the chemical structure (and structural abnormalities) of polymers. Among the examples described are the determination of the various olefinic groups, identification of substituted aromatics, crystallinity measurements, pyrolysis techniques, polyethylene branching studies, quantitative determinations, and following induced structural changes. Ultraviolet spectroscopy can also contribute to polymer studies. Examples such as the quantitative determination of polymer additives--i.e., antioxidants, expanding agents, slip agents, etc.--are described.