Intelligent Viscoelastic Polyurethane Intrinsic Nanocomposites

Abstract

Polyurethanes are multiphase systems comprising intrinsically variant nanodomains. The material properties can be tailored by adjusting the relative proportions and organizing the structure of the hard and soft segments akin to the spring-dashpot system in an automobile. This article describes how an intelligent polyurethane (PU) system is created to offer smart response to mechanical and vibration stimuli. In this work, unidirectional, dynamic mechanical thermal analysis (DMTA), acoustic, and impact testing results are qualified with the unique viscoelastic character that determines the rate-temperature response of the nanocomposite. Attenuated total reflection– infrared spectroscopy (ATR-IR) and DMTA offer a logical explanation of the observed viscoelastic behavior in terms of the nanodomains. Enhanced nanophase segregation between the polymer building blocks (hard and soft segments) is the primary mechanism that leads to a higher loss tangent peak in DMTA at a lower glass transition temperature (Tg) for greater energy dissipation in the polymer matrix. Acoustic and impact attenuation are correlated with the mechanical modulus and loss tangent of the polymer. Finally, autodyne simulation reveals the unique shock absorbent behavior of the material layer when retrofitted to concrete structure. Typically, shock overpressure spikes of the order of 9.97 × 104 MPa experienced by the unprotected surface are entirely evened out at a lower overpressure threshold.