Biaxially oriented polylactic acid (BOPLA) films were prepared by twin-screw extruder and static stretching machine, and they were buried in outdoor soil. The natural degradation process and mechanism of the BOPLA films were studied by analytical balance, Fourier transform infrared spectoscopy (FI-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The results show that the BOPLA film degrades slowly due to its dense surface at the initial degradation stage. After degrading for 10 months, the dense layer on the surface is eroded seriously, and the degradation goes deep into the film, the degradation is accelerated. The crystallinity, grain size, glass transition temperature, and other properties, which affected by the degradation of crystalline and amorphous regions, reach the peak value after degrading for 3 months, and then show a fluctuating downward trend.
| 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 |