Photooxidation of spherilene linear low-density polyethylene films subjected to environmental weathering.: 1.: Changes in mechanical properties

Films of a new linear low-density polyethylene (LLDPE) were exposed to natural weathering in southern Italy, for increasing times. Infrared analysis was used to detect the degradation products and the carbonyl index was related to the photooxidation products. The changes in mechanical properties due to the chemical degradation were followed by determining the drawing curve and the elastic modulus. All the mechanical parameters were correlated to the exposure time and to the carbonyl index, determined on the same samples. The change in the carbonyl index and the mechanical parameters with the exposure time allowed the determination of the point beyond which the material becomes useless. Furthermore, it was possible to calculate the ratio between natural and artificial time of degradation, which was found to be about 30. (C) 2004 Elsevier Ltd. All rights reserved.