Abstract: Two PBAT biodegradable films（biodegradable film 1 and biodegradable film 2） and a PE film were used as research materials, and the degradation characteristics of different films were studied by indoor culture experiment, scanning electron microscopy （SEM） and Fourier transform infrared spectrum （FTIR） under different soil moisture and different temperature culture conditions. The results showed that, when the films were cultured for 90 d under three different soil temperature conditions of 20 ℃, 40 ℃, 20 ℃ （12 h） and 40 ℃ （12 h） day and night alternation （20 ℃/40 ℃） respectively at the soil moisture content of 20%, the weight loss rates of the common PE membrane, biodegradable film 1 and biodegradable film 2 were the highest at 20 ℃/40 ℃, reaching to 2.89%, 11.91%, 8.33%, respectively. When the films were cultured for 90 d at 15%, 20%, 25% and 30% soil mositure respectively at 20 ℃, there was no significant difference in the degradation degree of PE film, while the biodegradable film 1 had the highest weight loss rate of 5.36% at 30% soil mositure, and that of the biodegradable film 2 was 6.46% at 25% soil mositure. It could be speculated that the Norrish type I reactions occurred in the two biodegradable films after 90 d of culture based on the FTIR. The expansion vibration of the two biodegradable films was obvious at 20 ℃/40 ℃, representing the molecular strand fracture. SEM showed the change trend of the morphological characteristic of the PBAT biodegradable films degradation was consistent with the law of matrix drop—crack/small penetrating holes—large area crack/large penetrating holes. It was concluded that the degradation degree of PBAT biodegradable films was significantly higher than that of PE film, and the high temperature and humid soil environment was conducive to the degradation of PBAT biodegradable films.

Key words: PBAT biodegradable film, soil moisture, soil temperature, degradation characteristics, scanning electron microscopy （SEM）, Fourier transform infrared spectrum （FTIR）