Realization of polyurethane/epoxy interpenetrating polymer networks with a broad high-damping temperature range using β-cyclodextrins as chain extenders

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Damping materials, especially high-damping (loss factor (tanδ) > 0.5 and above) materials, are widely applied for suppressing vibration and controlling noise in industrial field, but achieving a high tanδ over a wide temperature range is a challenging task. Herein, we report a novel polyurethane (PU)/epoxy (EP) interpenetrating polymer network (IPN) damping material by using 21-hydroxyl β-cyclodextrins (β-CDs) as PU chain extenders. At a high ratio of hydroxyls to isocyanate groups, every β-CD underwent a different degree of chain expansion. Then these β-CDs grafting different numbers of PU chains generated different-size hard segments, thus increasing the species of motion units and widening the damping temperature range. The unreacted hydroxyls on β-CDs provided a large quantity of hydrogen bonding protons, which could form hydrogen bonds with urethane groups, thus facilitating an increase in the tanδ value. Therefore, PU/EP IPNs with a broad high-damping temperature range were successfully prepared. The results showed that PU/EP IPNs cured by β-CDs underwent a damping temperature range of 93.1 K (tanδ > 0.5), 82.4 K (tanδ > 0.7) and even 74.1 K (tanδ > 0.8), much better than the corresponding 32.9 K, 23.9 K and 20.5 K for traditional PU/EP IPNs cured by trihydroxyl trimethylolpropane (TMP).