PBS/PLA共聚物的合成及其对青菜生理指标的影响

Poly (butylene succinate) (PBS), polylactic acid (PLA) has been widely used as mulch film in the agriculture because ofits good biodegradability, but during the biological degradation process, the physiological effects of oligomer and monomer on thevegetables has been rarely reported. PBS/PLA copolymers (Mn=5×103, 8×103, 1.6×104) were synthesized by the two-stage meltpolycondensation method composing of esterification and polycondensation, and then studied the impact on protein mass fraction,chlorophyll mass concentration, MDA molality and POD activity during the different stages of green vegetable leaves. The resultsshowed that: (1) Compared with CK, the protein mass fraction and MDA molality with PBS/PLA copolymer (Mn=5×103, w=0.022%)treatment increased significantly, while chlorophyll mass concentration and POD activity was little changed at 7 d and 14 d. After 3weeks, the protein mass fraction, chlorophyll mass concentration and MDA molality decreased remarkably while POD activityincreased. (2) PBS/PLA copolymer (Mn=8×103) had no clear effect on protein and chlorophyll at 14 d, and then the protein andchlorophyll of the treatment (w=0.22%, 2.2%) decreased at a low level. (3) PBS/PLA copolymers (Mn=5×103, 8×103, w=0.022%)treatment had no significant effect on MDA and POD activity before 21 d, MDA decreased and POD activity increased at 28 d. In aword, the PBS/PLA copolymers and their residues have a certain risk to plant growth.