MXene与PBAT协同改性聚乳酸复合材料的结晶行为、热及介电性能

Crystallization Behaviors,Thermal and Dielectric Properties of MXene and PBAT Co-modified PLA Composites

以左旋聚乳酸(PLLA)为基体,MXene为增强相,聚己二酸/对苯二甲酸丁二醇酯(PBAT)为增韧相,通过溶液共混法制备了PBAT@MXene杂化助剂,再利用熔融共混法制备了一系列的MXene、PBAT@MXene改性聚乳酸复合材料。利用扫描电子显微镜(SEM)、广角X-射线衍射仪(WAXD)、偏光显微镜(POM)、差示扫描量热仪(DSC)、动态热机械分析仪(DMA)、维卡软化仪和介电测试仪等分别测试了聚乳酸及其复合材料的断面微观形貌、晶型、晶体形貌、结晶性能、热力学性能、耐热变形和介电性能。结果表明,MXene与PBAT杂化后其表面出现明显的包覆层;随着MXene的添加,PLA/MXene复合材料的断面呈现出脆性断裂特性,PLA的晶型未发生变化,但其结晶度有所下降,而耐热变形温度和介电常数提高;当2%的PBAT@MXene和49%的右旋聚乳酸(PDLA)添加到PLLA后,其PLLA/PDLA/PBAT@MXene复合材料的断面呈现出韧性断裂形貌,同时,其复合材料出现明显的立构复合晶体(SC)且结晶度提高,热变形温度和介电常数较纯PLLA的分别提高了31.7℃和41.7%。

Using L-polylactic acid(PLLA)as the matrix,MXene as the strengthening phase and polybutylene adipate terephthalate(PBAT)as the toughening phase,PBAT@MXene hybrid additives were prepared by a solution blending method.A series of MXene,PBAT@MXene modified polylactic acid composites were prepared by a melt blending method.Subsequently,scanning electron microscope(SEM),wide-angle X-ray diffractometer(WAXD),polarizing microscope(POM),differential scanning calorimeter(DSC),dynamic thermomechanical analyzer(DMA),Vica softener and dielectric tester were used to examine the morphologies of sections,crystal forms,crystal morphologies,crystallization properties,thermodynamic properties,heat-resistant deformation and dielectric properties of polylactic acid and its composites.The results show that the surfaces of MXene are obviously coated by PBAT phase.Moreover,with the addition of MXene,the cross sections of PLA/MXene composites present brittle fracture characteristics,the crystal forms of PLA do not change,while the crystallinity of PLA decreases,and the heat deformation temperature and dielectric constant increase.When a 2%mass fraction PBAT@MXene and a 49%mass fraction D-polylactic acid(PDLA)are added into PLLA,the cross sections of PLLA/PDLA/PBAT@MXene composite emerge a ductile fracture morphology,and this composite possesses obvious stereo-composite crystals(SCs)with increased crystallinity.The heat deformation temperature and dielectric constant of this composite are 31.7℃and 41.7%higher than those of pure PLLA,respectively.