聚乳酸／醋酸淀粉共混物性能形态研究

采用双螺杆挤出机制备聚乳酸（PLA）／醋酸淀粉（AS）复合材料，研究不同螺杆结构和加工次数对复合材料流变-性能-形态的影响。测试结果表明：通过螺杆Ⅱ、二次挤出后的复合材料的力学性能最优，As含量为60％的复合材料拉伸强度达到27．91MPa。动态流变和SEM的结果表明采用螺杆Ⅱ可以提高PLA与As的共混效果。本文也考察了AS含量对复合材料的力学性能和动态流变性能的影响，结果表明当AS质量含量从45％提高到70％时，复合材料的拉伸强度从36．7MPa降低到16．4MPa；其复数黏度和储能模量则随着AS含量的增加而增加。

Characterization of Poly(lactic-acid)/Acetylated Starch Blends

The blend of poly（lactic-acid）（PLA） and acetylated starch （AS） with substitute degree 3.0 （DS=3） were prepared by a co-rotating twin-screw extruder with two kinds of screw configurations. The effect of screw configurations （Ⅰ and Ⅱ） and different processing times on the properties of the blends,including dynamical rheological properties, mechanical properties and morphology of PLA/AS blends were investigated. The results showed the screw H with a lower shearing force can decrease the degradation of the blends, and the mechanical property of PLA/AS （40/60） blend was optimal with two processing times through the screw H, the tensile strength of the blend was 27.91MPa, and indicated multiple processing can enhance the dispersion and the interfacial compatibility of PLA and AS. The influence of AS content on mechanical properties and dynamical rheological properties of the blends was also investigated. The results showed that when the AS content increase from 45% to 70%, the tensile strength of blend decreased from 36.66MPa to 16.36MPa, while their complex viscosity and the storage modulus increased with the increase of AS content and the frequency.