作者：Ran Niu, Jiang Gong, Donghua Xu*, Tao Tang, Zhao-Yan Sun*
关键字：molecular weight, structure, rheological properties
论文来源：期刊
具体来源：Polymer
发表时间：2014年

The structure and rheological properties of graphene oxide (GO)/polydimethylsiloxane (PDMS) composites are examined as the molecular weight of PDMS and concentration of GO are varied. Clusters formed by GO sheets get smaller and disperse better with increasing molecular weight of PDMS, which results in the higher critical concentration to form network (C_cr). Moreover, at GO concentration just above C_cr, the plateau modulus of samples decreases with the molecular weight of PDMS. During shear experiments, negative normal stress differences (DN) are observed in composites with PDMS molecular weight lower than critical entanglement molecular weight (M_c). However, positive DN is found in samples with PDMS molecular weight above Mc. It can be concluded that the vorticity alignment of GO clusters induces the negative DN based on the optical shear experiments. The possible mechanism for the positive DN is also proposed.