Full
Outline
To investigate the effects regularity of ultraviolet aging duration on the migration behavior of lead (Pb), acrylamide (AM) and 1,2-benzisothiazolin-3-one (BIT) in polylactic acid (PLA)/plant fiber composite food contact material, and reveal their microstructural evolution mechanism.
Ultraviolet accelerated aging tests were conducted to simulate natural aging. The changes in chemical structure were analyzed by Fourier transform infrared spectroscopy (FTIR), and the surface morphology of the material was observed by scanning electron microscopy (SEM). Migration levels of Pb, AM, and BIT into 4% acetic acid and olive oil food simulants were quantitatively determined at different migration time points (2 h to 48 h) by inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography (HPLC), respectively.
Long term ultraviolet aging promoted the migration of harmful substances. For the 45 d aging group, the 48 h migration amounts of Pb, AM and BIT increased to 15.10, 132.15 and 21.80 mg/kg, with increases of 46.7% (Pb), 56.1% (AM) and 47.3% (BIT) compared with the 0 d group. SEM observations showed that microcracks and pores formed on the material surface. FTIR analysis indicated photoxidative chain scission occurred in the PLA molecular chains, with the enhancement of carbonyl and hydroxyl peaks. Over 60% of the total 48 h migration for each substance occurred within the first 24 h.
It is recommended to add ultraviolet absorbers or coatings to improve the aging resistance of the material. For materials without anti-ultraviolet measures, based on the migration data of the aging experiment, the shelf life of the material is recommended to not exceed 240 d.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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