Mechanics of Polyborosiloxanes across Strain Rates and Strain Amplitudes

We report a comprehensive study of the dynamic mechanical properties of polyborosiloxane (PBS) tested using uniaxial compression, shear rheometry, compression DMA, impact loading, and vibrational transmissibility on a commercially available PBS formulation. We report properties for varying orders of magnitude in strain rate and as a function of strain amplitude wherever possible to quantify performance limits of PBS for different loading cases. We observe that in addition to undergoing a viscous to viscoelastic transition, PBS also experiences an increase in damping at sufficiently high strains within the viscoelastic regime, suggesting that losses arising from chain interactions in the polymer backbone decrease the effectiveness of the reversible B:Si in storing elastic energy at high strain rates for a given PBS formulation. Further, our results suggest that the onset of damping increase depends on the strain as well as the strain rate, with transitions occurring at 0.18 s–1, 1.48 s–1, and between 50 and 150 s–1 for strains of 0.03%, 0.7%, and 15%, respectively. These results inform the use of PBS for energy dissipation applications such as impact and vibration damping, as well as serving as a benchmark to aid in cross-comparison of other application-driven work with comparatively limited mechanical test campaigns.