聚合物/黏土纳米复合材料的流变行为研究

Advances in the Rheology of Polymer-based Clay Nanocomposite

目前对于聚合物纳米复合体系的流变行为的理解远不如大颗粒填充体系深入和系统。但无论是球形颗粒还是层状黏土颗粒的填充体系,人们通常可以观察到与高浓度大颗粒填充体系类似的流变特征,即:在整个频率范围内,模量均随纳米粒子的浓度升高而增大,且当填料浓度超过临界值后,储存模量在低频区会表现出似固体的平台发展(非末端行为)。由于非常低的填充粒子浓度,纳米复合体系流变行为反映出的这种似固体行为显然无法用高浓度大颗粒填充体系的网络形成来解释。考虑到纳米颗粒周围的受限条件以及层状黏土在力场作用下可能发生取向等因数,受限高分子链的阻尼松弛和局部有序造成的逾渗都曾被用来说明纳米体系的这种流变行为,但对其流变松弛机理的理解似乎仍需进一步深入。

Nanocomposites show improved material properties such as a higher modulus, higher thermal stability, decreased flammability and barrier properties, increased biodegradability of biodegradable polymers and various other properties in comparison with the virgin polymers or conventional composites.In order to understand the processibility of these materials,i.e.the final stage of any polymeric material,one must understand the detailed rheological behavior of these materials in the molten state.Understanding the rheological properties of nanocompositemelts is not only important in gaining a fundamental knowledge of the processibility,but is also helpful in understanding the structure-property relationships in these materials.