Photo-oxidation and biodegradation of polyethylene films containing polyethylene glycol modified TiO2 as pro-oxidant additives

Nano-TiO2 particles were modified with poly(ethylene glycol) (PEG) and used as pro-oxidant additives for degradable low-density polyethylene (LDPE) films. The photo-oxidation and biodegradation of polyethylene films containing modified nano-TiO2 particles were examined by exposure to UV irradiation for 370 hr followed by their incubation with mature compost and fungal strains isolated from soil. It is found that films with pro-oxidant additives showed an obvious decrease in molar mass, molecular weight, and mechanical properties and an increase in their carbonyl index during the photo-oxidation. In addition, the degradation rate under UV irradiation could be controlled by an addition of small amount of hindered amine light stabilizer. Furthermore, a profuse growth and colonization of fungal mycelia and spores on the photo-oxidized TiO2/PEG/LDPE composite films were observed while no colonization of fungal mycelia on the photo-oxidized LDPE films and photo-oxidized TiO2/LDPE composite films. The hydrophilic modification of TiO2 by PEG facilitates the photo-oxidation LDPE into small molecular weight residues which was easily consumed by fungal mycelia, leading to enhanced biodegradation. POLYM. COMPOS., 39:E531-E539, 2018. (c) 2017 Society of Plastics Engineers