Abstract: Films and containers are made from polymers of propylene such as polypropylene which contains a small amount of stabilizer whereby the rapid degradation rate of polypropylene can be controlled so that it will degrade after predetermined exposure to sunlight. This renders such products especially suited for agricultural mulch films, where they need not be removed after a growing season, and for throw-away containers where they will decompose in garbage dumps or if discarded as litter. The thermal history of the polymer will also affect its degradation rate.The rate is measured in terms of thermally adjusted Langley units (TALU) since it has been found that the ambient temperature affects decomposition as well as the Langley units of solar radiation exposure.