Abstract:

In this paper, polylactic acid （PLA） and polybutylene adipate terephthalate （PBAT） were used as raw materials to prepare biodegradable PLA-PBAT polyester blends with different proportions by twin-screw extruder and plate vulcanization mechanism. The processing properties, mechanical properties, micromorphology, thermal properties and hydrophobic properties of the blends were tested. The degradation properties of the polyester blend in natural light, natural water and forest soil were tested. The results show that the PLA-PBAT polyester blend prepared by melt blending is a physical blend without chemical reaction. The addition of PBAT reduces the melting point of the blend and the maximum torque and equilibrium torque. The addition of PBAT promotes the crystallization process of PLA, and the peak crystallization temperature of the melt gradually increases and the crystallization peak area significantly expands. The addition of PBAT has little effect on the glass transition temperature of the blend, and the crystallinity increases first and then decreases with the increase of the proportion of PBAT, and the hydrophobic property is enhanced. The crystallinity of PBAT-15% samples reaches a maximum of 40.8%, and the cold crystallization temperature is 98.1 ℃. The elongation at break of PBAT-15% samples reaches a maximum of 308.4%. Degradation test shows that the degradation rate of PLA-PBAT blend plastic bag is the fastest in forest soil, and it can be used as an environmentally friendly and green packaging material.

Key words: polylactic acid, polybutylene adipate terephthalate, polyester material, biodegradation, hydrophobic property