The Effect of Cobalt Naphthenate and 2-Hydroxy- 4-methoxybenzophenone on Photo-oxidative Degradation of LDPE.

The widespread use of polyethylene films as packaging materials is due to its exceptional mechanical properties and reasonable cost. These films are usually discarded after single use and because of their high molecular weight and absence of functionalities the degradation time is very slow and their wastes cause major pollution problem in our land fields. Increasing the degradation rate of these materials by incorporation of initiator and sensitizer is a major issue of research topics in this field. In this work, the effects of cobalt naphthenate and 2-hydroxy-4-methoxybenzophenone on photo-oxidative degradation of low density polyethylene (LDPE) have been studied. The degradation was monitored by measuring the changes in the carbonyl index, changes in tensile strength, elongation-at-break, crystallinity, and density. The measurements were performed before and after UV-irradiation at 30 days interval for 3 months. From the results of these measurements, it was observed that the UV-irradiation affects the LDPE and the rate of degradation increases with increasing the concentration of the cobalt naphthenate. The increasing rate of degradation becomes more obvious by varying the concentration of cobalt naphthenate and irradiation time. 2-Hydroxy-4-methoxybenzophenone shows a retarding effect on UV-degradation.