PBAT生物降解地膜在农田土壤和模拟土壤环境的降解行为研究

Degradation behaviors of PBAT biodegradable mulch film in farmland soil and simulated soil environments

研究了以聚对苯二甲酸⁃己二酸丁二酯(PBAT)为主要原料的生物降解地膜在农田土壤环境和模拟土壤环境中的生物降解行为,探究了聚酯相对分子质量、有机填料等因素对两种土壤环境中地膜降解速率的影响。结果表明,降解过程中,生物降解地膜PBAT分子链酯键断裂、结晶度升高,LN⁃1、LN⁃3、LN⁃5的O/C元素含量比分别增加54%、105%、184%;相同环境中较低相对分子质量聚酯降解更快;有机填料淀粉能够加快地膜物理崩解和生物降解过程。利用羰基指数变化建立土壤环境降解程度—时间一次、指数以及幂函数方程,其中幂函数方程决定系数最高、相关性最强,并据此建立农田土壤环境与模拟土壤环境地膜降解时间对应幂函数方程关系,实验室模拟了华北平原夏收后翻入农田地膜的降解行为。

This present work focuses on the biodegradation behavior of poly(butylene adipate⁃co⁃terephthalate)(PBAT)biodegradable mulch film in farmland soil and simulated soil environments.The effects of polyester relative molecular weight and organic fillers on the degradation rate of mulch film in two soil environments were investigated.During the degradation process,the breakage of ester bond in PBAT molecular chain occurred,and meanwhile the crystallinity of PBAT increased.The O/C content ratio of the samples LN⁃1,LN⁃3 and LN⁃5 increased by 54%,105%and 184%,respectively.The lower molecular weight polyester degraded faster in the same environment.Organic filler starch can ac⁃celerate the physical disintegration and biodegradation process of the mulch film.The linear,exponential,and power function equations for the degradation degree⁃time relationship was established by using carbonyl index changes,in which the power function equation performed the highest coefficient of determination and strongest correlation.Accordingly,a power function equation relationship between the degradation time of the mulch film in farmland and simulated soil envi⁃ronments was obtained.The degradation behavior of the mulch film converted into soil after summer harvest in North China Plain was simulated in the laboratory.