Abstract
Ever increasing ozone concentrations in the earth's atmosphere polluted by photochem ical smog raise the question of possible ageing of fibers in such an environment. This paper investigates polypropylene fibers characterized by pronounced ageing in the natural environment under the impact of sunlight. Fibers are exposed to ozone for varying times and temperatures in a concentration range that can be expected in a heavily polluted urban industrial environment. Changes in the level of chemical composition and molecular configuration are investigated, together with morphological characteristics and end-use properties. Results indicate that, even under relatively mild ozone conditions, hydroper oxide groups are created, morphological surface changes occur, fibers become more brittle and lose strength, and the isotacticity of the configuration is pronounced, but there are some rather positive effects as well.
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