热塑性淀粉/蒙脱石复合材料性能研究

用柠檬酸活化蒙脱石(CMMT),用尿素和甲酰胺塑化热塑性淀粉(UFTPS),制备了热塑性淀粉/蒙脱石(UFTPS/CMMT)复合材料.广角X-ray衍射(WAXD)、透射电子显微镜(TEM)表明,UFTPS和CMMT形成复合材料.CMMT质量分数2%~10%时,将复合材料在相对湿度50%(RH=50%)的环境下保存10 d,力学测试得出,复合材料的最大拉伸应力达到24.86 MPa,应变为134.50%,杨氏模量和断裂活化能分别由UFTPS的87.25MPa,1.87 N.m上升到复合材料625.25 MPa,2.45 N.m;可以看出,和纯UFTPS相比,复合材料强度明显提高;流变行为研究得出,通过改变加工温度和螺杆挤出机速度可以调整复合材料的流变行为;与传统的甘油体系相比,复合材料很好的抑制了材料长时间放置的结晶行为;并且该材料比纯UFTPS具有很好的耐水性能和热稳定性.

STUDIES ON PROPERTIES OF THE THERMOPLASTIC STARCH/MONTMORILLONITE COMPOSITES

The composites of thermoplastic starch plasticized by urea and formamide/citric acid-activated montmorillonite(UFTPS/CMMT) were prepared by the method of melt-intercalation.The ratio of urea and formamide used was 2∶1.Wide angle X-ray diffraction(WAXD),transmission electron microscope(TEM) studies revealed that UFTPS was intercalated into the layers of CMMT successfully and formed composites with CMMT.When the CMMT content was 2 wt%～10 wt%,after the composites had been stored at a reletive humidity of 50% for 10 days,the mechanical testing indicated that the maximum tensile strength of the composites reached 24.86?MPa,and the tensile strain reached 134.50%,Youngs modulus increased from 87.25?MPa for pure UFTPS to 625.25 MPa for UFTPS/CMMT composites,and the breaking energy increased from 1.87?N·m to 2.45? N·m,which showed that mechanical properties of composites were evidently better than those of UFTPS.Rheology analysis illustrated that during the process of composite preparation both the extruder screw speed and the processing temperature could effectively adjust the flow behavior of composites.Comparing with traditional GTPS,the composites greatly reduced the recrystallization resulting from long time storing.In contrast to pure UFTPS,the composites had better water resistance and thermal stability.