聚氨酯/石墨烯纳米复合物的原位制备及温度-电阻行为

In situ Preparation and Resistivity-Temperature Behavior of Polyurethane/Graphene Nanocomposites

采用原位聚合法,利用蓖麻油基聚氨酯预聚体与还原石墨烯残留羟基或羧基反应,制得聚氨酯/石墨烯纳米复合物,并利用红外光谱和拉曼光谱对其分子结构进行了表征.此外,分别采用热重分析仪、X-射线衍射、扫描电子显微镜、ZC36型高阻计等表征手段对其热稳定性、形态结构以及电阻率-温度行为进行了分析.结果显示,石墨烯添加致使复合物的交联网络增加和物理交联增强.因而,聚氨酯/石墨烯复合物的室温电阻率有所升高和电阻率-温度行为增强.尤其是,当掺杂3%石墨烯时,聚氨酯复合物的正电阻率温度效应(PTC效应)提高近3个数量级.因此,聚氨酯基复合物应该是一种具有潜在应用价值的低掺杂PTC纳米复合物材料.

Polyurethane/graphene （PU/RGO） nanocomposites were prepared by in situ polymerization of the residual hydroxyl or carboxyl groups on graphene with the castor oil-based polyurethane prepolymer,and their molecular structures were characterized by FTIR and Raman spectroscopy. In addition,the thermal stability and morphological structure and resistivity-temperature behavior of PU/RGO nanocomposites were investigated by thermogravimetric analyzer （TGA）, X-ray diffraction （XRD）, scanning electron microscope （SEM） and ZC36 high resistance meter,respectively. The restilts indicated that the addition of the graphene led to the increase in the cross-linked network owing to the reaction of more --NCO groups of PU with graphenes, and the enhancement in physical crosslink amongst the polyurethane-based composites owing to the effect of the relative free graphene residual. As a result, the PU/RGO composites showed a slight increase in room-temperature resistivity due to the combined effect of crosslink network and physical crosslink reaction on the conductive network. When the temperature value reached a critical temperature,the rapid expansion of the volume of PU- based polymer destroyed the significant reductive network of graphene, resulting in the remarkable enhancement in the resistivity-temperature behavior of PU/RGO composites. Especially, at the loading of 3 wt% graphene hybrid filler in PU matrix, PTCR behavior of the composites was observed with resistivity increase of nearly 3 orders of magnitude. Therefore, it is expected that the PU-based composites with a few contents of graphene might be the promising PTCR materials.