Tuning sound absorbing properties of open cell polyurethane foam by impregnating graphene oxide

In this paper, the effect of graphene oxide (GO) loading on sound-absorbing properties of open cell polyurethane foam (PU) was investigated. GO was impregnated into PU foam by a step-by-step vacuum-assisted process. It was found that sound -absorbing properties can be greatly enhanced by GO impregnation. Especially, sound -absorbing properties can be tuned to be maximized to specific frequency range by controlling GO impregnation density. To evaluate sound absorption performance, sound absorption coefficients were measured using an impedance tube. The averaged sound absorption coefficient ((alpha) over bar (800Hz similar to 6300Hz)) from 800 Hz to 6300 Hz was increased more than four times by impregnating 15 wt% of GO into 5-mm-thick PU foam with a bulk density of 51 kg/m(3). Foam parameters such as porosity, Young's modulus, and flow resistivity were determined as a function of GO concentration. Among those parameters, specific flow resistance had the greatest influence on sound-absorbing properties. Elastic porous material theory was used to model sound -absorbing properties of GO impregnated PU foam, which showed good agreement with measurements at every GO loading condition. The pore tortuosity, which was determined using a fitting procedure, exhibited a good linear relationship with GO loading. It was found that impregnation of GO significantly increased tortuosity. The results given here suggest theoretical and experimental guidelines for use of GO to improve and optimize the sound-absorbing properties of PU foam. (C) 2019 Elsevier Ltd. All rights reserved.