Effect of sunlight expousre on PET water bottles during long storage

Polyethylene terephthalate (PET), which used as bottles for drinking water, was studied under real storage conditions for 670 days (near Damascus in Syria). UV-B, UV-A spectrums of direct sunlight were measured during the experiment. Chemical leaching of acetaldehyde, acetone, and formaldehyde reached a highest level after 210 days of outdoor storage; it were 345 ± 18 ?g/L, 434 ± 22 ?g/L, and 94 ± 5 ?g/L, respectively after storage (one year) under direct sunlight. The increase due to sunlight storage in comparison with laboratory storage (in dark) was estimated to be around 16%, 10%, and 36%, respectively. Migration of some ions and cations was less sensitive to outdoor storage, a slight increase was observed during the storage period. The PET bottle damage was studied by FTIR-ATR analysis; novel peaks appeared after 313 days at the regions 1920-1770 cm-1, 1685-1490 cm-1, which could be due to the photodegradation and thermo-degradation of PET material. Sunlight exposure, temperature, and water contact were the principle variables which affect on the morphology of PET in addition to its mechanical and thermal properties. Slight changes in the crystallinity during the storage period were observed by different methods (DSC, FTIR, Xray and density). The results of this study showed that an augmentation in the degree of crystallinity of outdoor aged PET samples from 18% to 36% accompanied with a decrease in tensile strength from 167.9 MPa to 133.7 MPa. Moreover, a good exponential correlation found between the degree of crystallinity and the mechanical properties of aged PET. Additional experiments carried out with a view to modifying the thermal and mechanical properties of PET (using the gamma radiation and E-beam) in order to maintain water quality and to reduce the migration of the studied compounds from the PET bottle into water and, so the dose of 20 kGy was adopted. Du to their impact on public health as well as water control in terms of physical properties, Phthalates (Dimethyl, Diethyl, Di-butyl phthalate) were investigated in the PET bottled water for a period of six months under different storage conditions. The concentration of phthalates ranged between from 1.5 to7.8 ?g/L after six months of storage. The highest concentrations of phthalates were found in the water stored in PET under sun compared with bottles stored in the dark.(author)