Fe_3O_4/聚苯乙烯纳米复合材料的结构与性能

Structure and Properties of Fe_3O_4/Polystyrene Nanocomposites

采用油酸（OA）表面改性的粒径均一的Fe3O4纳米粒子（0A-Fe3O4）与工业化聚苯乙烯（PS）通过溶液共混挥发干燥方法得到了具有超顺磁性的OA-Fe3O4／PS纳米复合材料．透射电子显微镜表征结果表明，在OA-Fe3O4质量分数为1％-10％时，OA—Fe3O4纳米粒子均匀分散在PS聚合物基体中．示差扫描量热分析表明，随着纳米粒子加入量的增加，纳米复合材料的玻璃化转变温度逐渐降低．热失重分析表明，OA-Fe3O4的存在显著提高了PS在空气条件下的热稳定性．流变分析表明，随着纳米粒子加入量的增加（0～10％），复合材料黏度逐渐降低．进一步研究了分子量双峰分布的PS与OA-Fe3O4纳米复合体系的流变行为，结果表明，当PS基体的平均分子量大于临界缠结分子量，且填充的纳米粒子的半径小于双峰分布PS的均方旋转半径时，加入纳米粒子仍然导致体系的复合黏度降低．

Oleic acid modified Fe3O4 nanoparticles（ OA-Fe3O4 ） with uniform particle size were blended with polystyrene（PS） by solution-mixing/evaporation drying method. The resultant PS/Fe3O4 nanocomposites exhibited superparamagnetic property. It was found that OA-Fe3O4 nanoparticles were well dispersed in PS matrix, when the content of OA-Fe3O4 was 1%-10% （mass fraction）. Differential scanning calorimetry（ DSC ） analysis showed that the glass transition temperature（ Ts ） of PS nanoeomposites decreased with the increase of the amount of Fe3O4 nanoparticles. According to the results from thermal gravimetric analysis （TGA）, the presence of OA-Fe3O4 would significantly enhance the thermal stability of PS under air condition. Rheological analysis showed that the melt viscosity of PS nanocomposites decreased with the increase of the amount of nanoparticles（0-10% ）. Furthermore, we also found that the viscosity reduction took place in the PS with bimodal distribution after adding OA-Fe3O4, when the average molecular weight of PS was higher than critical entanglement molecular weight of PS and the radius of nanoparticles was smaller than PS＇ s mean-square radius of gyration.