Modified polylactic acid with gradient crystallinity and preparation method and application thereof

The invention provides modified polylactic acid with gradient crystallinity and a preparation method and application thereof, and relates to the technical field of biodegradable packaging materials. The modified polylactic acid with gradient crystallinity can be prepared by controlling the temperature difference of the opposite surfaces in the forming process of the modified polylactic acid product and using the nucleating agent and the flexibilizer in a matched manner. The modified polylactic acid with gradient crystallinity prepared by the invention can overcome the defects of poor heat resistance of low-crystallinity polylactic acid and high brittleness of high-crystallinity polylactic acid, and greatly widens the application range of polylactic acid materials. 本发明提供了一种具有梯度结晶度的改性聚乳酸及其制备方法和应用，涉及可生物降解包装材料技术领域。本发明通过控制改性聚乳酸制品成型过程的相对面的温度差，再配合成核剂和增韧剂的使用，能够制备得到具有梯度结晶度的改性聚乳酸。本发明制备的具有梯度结晶度的改性聚乳酸可以克服低结晶度聚乳酸耐热性能差和高结晶度聚乳酸脆性大的缺陷，大大拓宽了聚乳酸材料的应用范围。