目的 通过对广泛使用的PBAT–PLA生物降解膜袋在受控需氧堆肥条件下的降解机制研究，为生物降解塑料的大规模推广提供重要理论基础。方法 根据GB/T 19277.1—2011，在(58±2)℃需氧条件下，对PBAT–PLA膜袋进行为期160 d的生物降解测试(即工业堆肥)，并以常见的可降解材料微晶纤维素作为参比样品。对降解前后的材料进行红外、扫描电镜、能谱分析，并结合其所在堆肥样本的脂肪酶活性，从多角度探寻降解机制。结果 PBAT–PLA膜袋与微晶纤维素所在的堆肥脂肪酶活性都达到空白堆肥的3倍以上。红外显示由微晶纤维素水分子吸附、糖环打开、基团氧化形成的吸收峰加强，PBAT–PLA膜袋中的酯键峰明显减弱;扫描电镜发现降解的PBAT–PLA膜袋表面覆盖了微生物膜;能谱分析发现，碳元素大幅减少，氧元素增加。结论 微生物在PBAT–PLA膜袋表面生长形成生物膜，分泌大量脂肪酶，水解PBAT–PLA的酯键，使聚合物降解为不同链长的中间体或小分子，同时伴随着氧化，随后被作为碳源，在相关微生物体内被代谢利用，形成最终产物。

The work aims to study the degradation mechanism of widely used PBAT-PLA biodegradable packaging under controlled aerobic compost, so as to provide an important theoretical basis for the large-scale promotion of biodegradable plastics. According to GB/T 19277.1-2011, the biodegradation test (i.e., industrial compost) of PBAT-PLA packaging was carried out for 160 days under the aerobic condition at (58±2) ℃. The biodegradable microcrystalline cellulose was used as reference. The materials before and after degradation were analyzed by infrared ray, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS). The lipase activity of the compost was also tested. The degradation mechanism was explored from multiple angles. The lipase activity of compost containing PBAT-PLA packaging and microcrystalline cellulose was more than 3 times that of blank compost. Infrared spectra showed that the absorption peak formed by water molecule adsorption, sugar ring opening and group oxidation in microcrystalline cellulose was strengthened. The peak of ester bond in PBAT-PLA packaging was significantly weakened. SEM showed that the surface of degraded PBAT-PLA packaging was covered with biofilm. EDS showed that carbon content decreased significantly and oxygen content increased. Microorganisms grow on the surface of PBAT-PLA packaging and form biofilm, and then secrete lipases to hydrolyze the ester bond in PBAT-PLA, so that the polymers are degraded into intermediates or small molecules with different chain lengths, accompanied by oxidation. Finally, the polymers are metabolized and utilized in degradation related microorganisms as a carbon source, forming final metabolites.