Interpenetration of Glassy <scp>PMMA</scp> in Rubbery Epoxy: Enhancing Vibration Damping Across a Wide Frequency Range

ABSTRACT Interpenetrating polymer networks (IPNs) are known for their vibration damping application in a broad frequency range. In the present work, we have synthesized a series of sequential IPNs comprising polyether amine‐cured epoxy and polymethyl methacrylate (PMMA) crosslinked with tetraethylene glycol dimethacrylate (TEGDM). The effect of the concentration of PMMA on the viscoelastic properties of the IPNs was investigated using dynamic mechanical thermal analysis (DMTA). The IPNs exhibited an average loss factor of 0.3–0.4 across broad temperature and frequency scales, indicating a wide range of vibration damping capabilities. Structural damping of the pristine epoxy network and the IPNs was assessed experimentally as well as using a theoretical model for a constrained layer damping (CLD) arrangement. The IPNs demonstrated superior damping performance, with average system loss factors of 0.046–0.097, compared to 0.020 for the bare beam and 0.036 for the pristine epoxy matrix in the entire frequency range of 20–4000 Hz. More importantly, average system loss factors measured at low frequency up to 400 Hz are enhanced from 0.043 for the pristine epoxy matrix to 0.101–0.198. The IPNs with efficient vibration damping capability in such a broad frequency range (20–4000 Hz) can find industrial applications for damping a wide variety of machinery vibrations.