Multiscale Modeling of Mechanical Properties of Green Tire Tread Compound

Hypothesis: 

In elastomeric composites, interfacial phenomena such as the effect of reinforcing filler on molecular dynamics of the rubber chain in the interphase and the way of rubber-filler interaction are the source of strain energy change or viscoelastic loss of the composite in highly filled rubber compound. To obtain a preliminary approximation of how the strain energy is influenced by interfacial phenomena, including stiffness, loss and the quality of this region, in this research, the finite element microstructural model was created in two-dimensional and three-dimensional mode and the effective characteristic changes in mechanical properties were studied. The effect of the change in stiffness of the interphase and the change in viscoelastic nature, the amount of contact between the rubber-filler in completely bonded and frictional sliding states were modeled.

The solution styrene butadiene rubber composites reinforced with silica were prepared by melt mixing. For this purpose, rubber was mixed with silica and silane coupling agent in an internal mixer. Then the masterbatch was mixed with the curing system on a two-roll mill and finally the sample was cured under pressure at 160°C.

In agreement with the modeling results, the composite tensile test showed that the most important controlling parameter is the type of rubber-filler connection in the interphase. The simulation results showed that considering the interphase region with frictional sliding greatly reduces the stress transfer from the matrix to the particle. But in the case of the completely bonded interphase region, due to the complete transfer of stress from the particle to the matrix, the mechanical properties showed a significant deviation compared to the experimental results. Also, the 3D models provided better predictions than the 2D ones.