Tunable viscoelastic and vibration damping properties of a segmented polyurethane synergistically reinforced with carbon black and anisotropic additives

Abstract

The dynamic properties of filled elastomers have been a subject of both fundamental and applied research interest. We report on the tunable and synergistic effect of carbon black and anisotropic additives on the viscoelastic and vibration damping properties of a segmented polyurethane (PU). To this end, PU composites were prepared using aramid short fiber and graphite as micro-scale additives and organically modified nanoclay as the nano-scale anisotropic additive in conjunction with carbon black. The degree of hydrogen bonding, phase and filler dispersion morphology of the composites were ascertained by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Dynamic mechanical analysis of the composites revealed an additive induced decrease in the intensity of the dissipation factor, tan δ, implying immobilization of polymer chains in the vicinity of the filler surfaces and significant reinforcement effect of fillers on the PU matrix. The composite system loss factor evaluated from the modal analysis of frequency response, in constrained layer damping mode, revealed loss factor values in the range 0.1–0.2 (at 710 Hz), as against the corresponding value of 0.027 for the bare metal beam. A salient finding of the present study was the filler induced enhancement in system loss factor, while the tan δ magnitude decreased, which has been reconciled with several causal mechanisms.