Melt State Reinforcement of Polyisoprene by Silica Nanoparticles Grafted with Polyisoprene

We systematically vary the nanoparticle (NP) dispersion state in composites formed by mixing polyisoprene homopolymers with polyisoprene grafted silica particles, and demonstrate how creep measurements allow us to overcome the limitations of small amplitude oscillatory shear (SAOS) experiments. This allows us to access nearly 13 orders in time in the mechanical response of the resulting composites. We find that a specific NP morphology, a percolating particle network achieved at intermediate graft densities, significantly reinforces the system and has a lower NP percolation loading threshold relative to other morphologies. These important effects of morphology only become apparent when we combine creep measurements with SAOS reemphasizing the role of synergistically combining methods to access the mechanical properties of polymer nanocomposites over broad frequency ranges.

Automated summary

We investigated the mechanical properties of polymer nanocomposites by varying the dispersion state of nanoparticles. By performing creep measurements, we overcame the limitations of small amplitude oscillatory shear experiments and discovered the reinforcing effect and percolation loading threshold of specific nanoparticle morphology on the system.