Effect of shape and size of nanofillers on the viscoelasticity of polymer nanocomposites

Polymer nanocomposites (PNCs) are now widely used in various fields. It is modified by adding fillers to improve its various properties during processing and application. In this work, we investigated the viscoelasticity of PNCs respectively filled with nanoparticles, nanorods and nanosheets and compared the effects of filler shape and filler size. It is found that the nanorod has the most outstanding ability to increase the modulus of PNCs among the three, followed by the nanosheet. The increase of filler size can increase the modulus of the system and has little effect on Payne effect. The source of modulus enhancement of PNCs respectively filled with nanorods and nanosheets changes with increasing volume fraction from Rouse dynamics of the polymer chains to the binding force of the filler on the polymer chains and eventually to the filler network. Increasing the filler size makes the Rouse dynamics region and chain confinement region narrower and the permeation threshold lower. However, the source of modulus enhancement of PNCs filled with nanoparticles is mainly the Rouse dynamics of polymer chains, which only conforms to the above mechanism at a high interface degree of nanoparticles.