Development of a Viscoelastic Composition having Superior Vibration-Damping Capability

Abstract

An intensive investigation of polymers, plasticizers, and fillers was conducted with the resulting development of a viscoelastic material that effectively damps 38-in. steel plating. This vibration damping material exhibits greater than 3% critical damping over two decades of frequency, and a 45°F temperature range, at a one-third plate-weight application. At the temperature of maximum efficiency, the material exhibits greater than 9% critical damping over a decade of frequency. The viscoelastic damping material consists of a self-extinguishing vinyl chloride/vinyl acetate copolymer, and is capable of withstanding both saline water and JP-4 jet fuel. The application of this material in spaced and constrained damping systems results in the effective damping of steel plate up to 1.75 in. thick. The investigation also demonstrated that three types of fillers are useful in increasing the damping effectiveness of the polymer system: (1) flake, (2) granular, and (3) low-density granular. The flake filler (e.g., graphite) has the effect of both increasing damping and broadening the operable temperature and frequency range of the damping system. The granular filler (e.g., carbon black) reinforces the polymer network and thereby promotes energy loss. The low-density granular filler (e.g., wood flour) decreases the bulk density of the system without proportional reduction in damping effectiveness.