Edinburgh Napier University

  The introduction of self-healing and reprocessability into conventional vulcanized rubbers has been recognized as a promising strategy to promote elastomer circularity. However, the reversibility and recovery of cross-linking polymer networks have often been assessed by static mechanical testing, which highly limits the understanding of the underlying microscale mechanisms. In this work, we investigated the network recovery of natural rubber (NR)/carbon black (CB) nanocomposites using Fourier transform (FT) rheology coupled with large amplitude oscillation shear (LAOS) technology across linear and nonlinear regimes (0.01–500%). The self-healing process of the rubber composite networks was monitored by using a programmed time–temperature oscillation shear measurement. The role of CB particle size in the filler network recovery was also discussed from the perspective of strain-induced crystallization of NR. Coupling FT-rheology and LAOS analysis, two distinct nonlinear enhancement behaviors beyond the linear viscoelastic regime were detected in the rubber nanocomposites, which were ascribed to the filler network disruption followed by the polymer network deformation. The relationship of the nonlinearity parameter I 3/1 as a function of strain amplitude was selected to quantify the nonlinear rheological responses, where the role of the filler and polymer on the network recovery can therefore be differentiated. This work provides an efficient method to evaluate the self-healing and reprocessability of cross-linked rubbers and offers a fast-screen route for formulation development and sustainable rubber composite design.