Resolving cavitation in silica-filled styrene-butadiene rubber composites upon cyclic tensile testing

Cavitation phenomena were resolved in silica-filled styrene-butadiene-rubber composite upon cyclic tensile testing, prior to and after an accelerated thermal exposure. To this end, 3D digital image correlation (3D-DIC) and micro-computed x-ray tomography (mu CT) were employed with in-situ approaches. It was found that thermal exposure induced structural changes in the composite similar to those occurring in real tires, such as the increase of the crosslink density of the rubber matrix, and the increase of its stiffness. The 3D-DIC measurements revealed that the mechanical hysteresis and volume strain were higher in the thermally-treated composite. The mu CT results indicated three types of cavitation phenomenon as sources of volume change: i) debonding at the agglomerate poles, ii) internal agglomerate fracture and iii) a combination of both of them. Cavities were initially oblate and became more spherical when stretching the materials. The mu CT measurements confirmed a faster increase in size and sphericity of voids for the thermally-treated composite when deformed, which is probably due to the higher stiffness of the rubber matrix.

Automated summary

This study investigated cavitation phenomena in silica-filled styrene-butadiene-rubber composite during cyclic tensile testing before and after thermal exposure, using 3D digital image correlation and micro-computed x-ray tomography techniques. The results showed that thermal exposure led to structural changes in the composite, such as increased crosslink density and stiffness of the rubber matrix. It was observed that the thermally-treated composite exhibited higher mechanical hysteresis and volume strain during testing.