Ma Furui, Xu Bei, Song Yihu, Zheng Qiang
MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University Hangzhou 310027 China
RSC Adv. 2018 Sep 13;8(56):31972-31978. doi: 10.1039/c8ra04497j. eCollection 2018 Sep 12.
Molecular weight strongly influences the molecular dynamics and rheological responses of nanocomposites, which is far from being well understood. Herein molecular dynamics and rheological behaviors of hydrophilic fumed silica filled unentangled polypropylene glycol (PPG) were investigated as a function of weight averaged molecular weight ( ) of PPG and volume fraction () of silica. It is shown that does not affect the glassy layers surrounding the nanoparticles and the segmental dynamics of the mobile PPG phase. On the other hand, the mobile PPG phase in the highly filled nanocomposites exhibits an abnormal "more fragile" to "stronger" transition with increasing . The reinforcement and thinning behaviors are stronger in lower- nanocomposites with the "more fragile" mobile PPG phase. The results suggest that reinforcement of nanocomposites affects the dynamic fragility of the mobile phase of the matrix.
分子量对纳米复合材料的分子动力学和流变学响应有很大影响，而这一点目前还远未得到充分理解。在此，研究了亲水性气相二氧化硅填充的未缠结聚丙二醇（PPG）的分子动力学和流变行为，该行为是作为PPG的重均分子量（ ）和二氧化硅的体积分数（ ）的函数。结果表明， 不影响纳米颗粒周围的玻璃态层以及可移动PPG相的链段动力学。另一方面，随着 的增加，高填充纳米复合材料中的可移动PPG相表现出从异常的“更脆弱”到“更强”的转变。在具有“更脆弱”可移动PPG相的低 纳米复合材料中，增强和增稠行为更强。结果表明，纳米复合材料的增强作用会影响基体可移动相的动态脆性。
