石墨烯增强聚乳酸力学性能及其发泡行为研究

以熔融共混的方法制备了具有不同纳米填料含量的聚乳酸/石墨烯纳米片（PLA/GNP）复合材料，利用超临界CO₂（Sc?CO₂）辅助釜压发泡的方式，进而制备了PLA/GNP复合泡沫，采用扫描电子显微镜和旋转流变仪等对复合材料的微观形貌、力学性能、流变行为和发泡性能进行了表征，探讨了GNP对发泡行为的作用机理。结果表明，GNP在PLA基体中的分散情况较好，与纯PLA相比，GNP含量为3 %（质量分数，下同）的复合材料的强度与刚度提高了近20 %；随着GNP含量的逐渐提高，PLA分子链运动时受到的限制加大，对熔体黏弹性产生了明显的增强作用，有利于PLA发泡能力的提升；由于GNP的异相成核作用，获得的PLA/GNP复合泡沫具有30倍以上的发泡倍率，泡沫的压缩强度和模量分别提升了2.5和7倍。

Mechanical Properties and Foaming Behaviors of Graphene?reinforced Poly（lactic acid）

Poly（lactic acid） （PLA）/graphene nano?platelet （GNP） composites were prepared by melt blending with different GNP contents， and their micromorphologies， mechanical properties， rheological behaviors and foaming properties were investigated. The results indicated that GNP presented a good dispersion in the PLA matrix. Compared to pure PLA， the composites exhibited an improvement in tensile strength and stiffness by nearly 20 % at a GNP content of 3 wt%. In addition， the movement of PLA chains was restricted with gradually increasing the GNP content. This enhanced the viscoelasticity of composite melts significantly， which was beneficial to the PLA foaming. Owing to the heterogeneous nucleation of GNP， the composite foams presented a large foaming ratio more than 30 times， and their compressive strength and modulus increased by 2.5 and 7 times， respectively.