Effects of silica nanoparticles on the rheological properties and morphologies of polyvinyl alcohol/silver nanowire suspensions

We investigated the effects of silica nanoparticles (SiNPs) on the rheological properties and microstructures of polyvinyl alcohol (PVA)/silver nanowire (AgNW) suspensions. For PVA/AgNW suspensions without SiNPs, rheological percolation threshold was calculated using storage modulus determined by small amplitude oscillatory shear (SAOS) tests. Results from SAOS tests revealed that PVA/AgNW suspensions had two transition concentrations, which led to different structure developments. Storage modulus from large amplitude oscillatory shear (LAOS) tests showed double-step strain softening behavior at all AgNW concentrations tested, and elastic stress components, also obtained by LAOS tests, exhibited trends similar to storage modulus development. Furthermore, two distinguishable structures were observed when large strain amplitude shear was applied. When SiNPs were added to PVA/AgNW suspensions, the rheological properties of PVA/AgNW suspensions from SAOS tests increased. LAOS results showed storage modulus and elastic stress components of PVA/AgNW suspensions were dependent on AgNW concentration. Doublestep strain softening disappeared for PVA/AgNW suspensions containing SiNPs at low AgNW concentrations, whereas at high AgNW concentrations double-step strain softening behavior was observed.