ABSTRACT

Outdoor aging is too slow to be useful in development of stabilized formulations; therefore, accelerated aging is very much required to conduct weathering trials. The acceleration factors obtained for the photooxidation of polymers will depend on the degradation parameters measured. Some of the important parameters are oxygen uptake, carbonyl, end-unsaturation, and mechanical properties. It has been observed that the experimental design of artificially accelerated weathering is important because very high acceleration leads to a change in the mechanism that leads to oxygen uptake. In accelerated weathering, most oxygen is consumed through a propagation reaction, whereas in outdoor weathering, most of the oxygen is consumed by air initiation reaction caused by a charge transfer complex (CTC) of oxygen. It was suggested that a decrease of temperature or an increase of oxygen pressures during accelerated weathering might lead to more initiation through a CTC and then a better correlation with outdoor weathering.