左旋聚乳酸/右旋聚乳酸交替多层薄膜的结晶调控和高性能化

Crystallization Regulation and High Performance of Alternating Multilayer Films of L-Poly(lactic acid)/D-Poly(lactic acid)

通过溶液刮涂法,将浓度均为0.04 g/mL的左旋聚乳酸(PLLA)和右旋聚乳酸(PDLA)溶液用刮涂机层层交替涂覆烘干后制备成薄膜,并将PDLA/PLLA(1∶1)共混溶液及纯PLLA溶液用涂布机采用相同的方法制备出薄膜作为对比样。通过差示扫描量热分析、二维广角X射线衍射、扫描电子显微镜、万能拉伸机、压差法气体渗透仪研究了PDLA/PLLA交替多层结构对PLA结晶行为、微观形貌、力学性能及氧气阻隔性能的影响。结果表明,PLLA层与PDLA层之间可以形成二维连续立构晶层,二维连续立构晶层(2D-SC)还可以作为成核剂,诱导两侧连续有序PLLA横晶(PLLA-TC)与PDLA横晶(PDLA-TC)的生成。2D-SC晶体、PLLA-TC晶体及PDLA-TC晶体的存在可以大幅度提升聚乳酸的气体阻隔性能。

By solution coating method,l-polylactic acid(PLLA)and d-polylactic acid(PDLA)solutions with the concentration of 0.04 g/mL were alternately coated by scraping machine layer by layer and dried to prepare the films,and PDLA/PLLA(1∶1)blend solution and pure PLLA solution were prepared by coating machine at the same way to prepare the films as comparison sample.By differential scanning calorimetry(DSC),two-dimensional WAXD,SEM,universal drawing machine and differential pressure gas permeometer,the effects of PDLA/PLLA alternating multilayer structure on the crystallization behavior,microstructure,mechanical properties and oxygen barrier properties of PLA were studied.The results show that the two-dimensional continuous stereocomplex crystallites(2 D-SC)could be formed between PLLA layer and PDLA layer,and the two-dimensional continuous stereocomplex crystallites(2 D-SC)could also be used as nucleating agent to induce the generation of continuous ordered PLLA transcrystalline(PLLA-TC)and PDLA transcrystalline(PDLA-TC)on both sides.The presence of 2 D-SC,PLLA-TC and PDLA-TC can greatly improve the gas barrier properties of PLA.