PTC Behavior Based on Thermomechanical Properties in Graphene Nanosheets/Silicone Rubber Nanocomposites

Graphene nanosheets/silicone rubber (GNs/RTVSR) nanocomposites were fabricated to investigate the effect of thermomechanical–electrical coupling mechanism on their positive temperature coefficient (PTC) behavior. Heat treatment and graphene nanosheet size design were employed to tailor the thermal, mechanical, and electrical properties of the nanocomposites. Heat treatment removed organotin from the RTVSR matrix, as confirmed by XPS, FTIR, and in situ SEM, thereby enhancing the resistance stability of the nanocomposites. The slight variations in PTC behavior observed after treatment were associated with nanosheet size and transient temperature responses. Based on these results, the PTC mechanism governed by thermomechanical behavior and viscoelasticity was discussed. The steady-state PTC behavior of nanocomposites was described by a prediction model that combined thermomechanical and electrical conduction percolation. The PTC values of the nanocomposites with heat treatment and different GNs sizes could be predicted by this model. Meanwhile, DMA and other thermomechanical analyses revealed a strong correlation between time-dependent resistance attenuation and viscoelasticity of the nanocomposites. The PTC mechanism composed of steady model and transient analyses unmasked intensity differences and process deviation of resistance change rate. It explained the temperature self-limited heating behavior of nanocomposites.