超临界CO_2辅助挤出PLA/粘土纳米复合材料的流变-形态-力学性能

Dynamical Rheological Property,Morphology and Mechanical Property of Polylactic Acid/Clay Nanocomposites Using Sc-CO_2 in Extrusion

采用超临界CO2辅助挤出的方法,在双螺杆挤出机上制备了聚乳酸(PLA)/粘土纳米复合材料。采用旋转流变仪、透射电镜和力学性能测试对复合材料的流变、结构和性能进行了表征,分析超临界CO2对流变、形态和性能的影响。流变测试结果表明,纳米复合材料的复数黏度和储能模量均高于纯PLA,且表现出类固行为。透射电镜照片显示在加工流场中引入超临界CO2可使粘土在PLA基体中分散得更均匀。复合材料在拉伸过程中表现出屈服行为,断裂伸长率和拉伸强度分别从纯PLA的9.29%、41.60MPa提高到气体注入量为7%(质量分数,下同)时的24.74%、51.70MPa;无缺口冲击强度比纯PLA稍高。

The PLA/clay nanocomposites were compounded by a co-rotating twin-screw extruder with Sc-CO2.The dynamical rheological property,morphology and mechanical property of nanocomposites were investigated.The results show that the complex viscosity and storage modulus of the nanocomposites are higher than that of pure polylactic acid （PLA）.The solid-like behaviors of nanocomposite melts are observed.From transmission electron microscope （TEM） measurement,it is concluded that the clay is dispersed more homogeneous in the nanocomposites with Sc-CO2.The nanocomposites with the presence of clay yield in the tension test and the elongation at break and tensile strength is improved from 9.29%,41.60 MPa of pure PLA to 24.74%,50.93 MPa of the nanocomposites with 7% gas,respectively.The impact energy of the nanocomposites is slightly higher than that of pure PLA.