Photodegradation of LDPE containing gelatin encapsulated benzophenone

Abstract

Low Density Polyethylene (LDPE) is the most widely used packaging polymers and these products are designed and manufactured to resist environmental degradation that can generate a great amount of waste. The aim of this research was to control photodegradation of LDPE by incorporating encapsulated particles of benzophenone. The photodegradation was estimated by outdoor exposure test and accelerated weathering test. The progress in photodegradation of pure LDPE films and LDPE films containing additives were followed by observing the changes in weight loss, tensile properties, and carbonyl index (Cl) of the films. The morphological change of the films was followed by scanning electron microscopy (SEM). From the results, it was found that both gelatin and benzophenone can promote the photodegradation of LDPE film, although with different magnitude. The photodegradation of LDPE/gelatin film slightly increased with an increase of exposure time and gelatin concentration. However, benzophenone has a very high influence on photodegradation. The photodegradation of LDPE/benzophenone film was greater than pure LDPE and LDPE/gelatin films and rapidly increased with increasing exposure time and benzophenone concentration. Encapsulated benzophenone was prepared by simple coaceivation method to control the releasing rate of benzophenone. In order to control the thickness of coating material, two factors; i.e., the ratios of benzophenone to gelatin and the amount of formaldehyde, were investigated. Based on the tensile properties and carbonyl index values, it can be concluded that the photodegradation rate increased with decreasing the gelatin in the ratio of benzophenone to gelatin. LDPE film containing EN1 microcapsule degraded faster than LDPE film containing EN2 and EN3, respectively. In addition, it was found that the amount of formaldehyde had no effect on the photodegradation rate.