Experimental and finite element approach for finding sound absorption coefficient of bio-based foam

L. Yuvaraj1 , S. Jeyanthi2 , Lenin Babu Mailan Chinnapandi3

1, 2, 3Vellore Institute of Technology, Chennai, India

2Corresponding author

Journal of Vibroengineering, Vol. 21, Issue 6, 2019, p. 1761-1771. https://doi.org/10.21595/jve.2019.20335
Received 25 October 2018; received in revised form 18 June 2019; accepted 30 June 2019; published 30 September 2019

Copyright © 2019 L. Yuvaraj, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons License

The enormous consumption of Polyurethane foam leads to severe environmental pollution and health hazards, so it is necessary to overcome this problem. This paper presents alternative and less hazardous foam that differs from traditional foams. A bio-based foam was developed either by using castor oil-based polyol or natural fibers as fillers. In the present study, rigid foam is synthesized by both castor polyol and luffa fiber, whereas for flexible foam, only luffa fiber is incorporated. Luffa fillers enhance the porosity of Polyurethane foam, which is the dominating factor influencing the value of the sound absorption coefficient. Both rigid and flexible foams were developed with 5, 10 and 15 percentages of filler loaded. The samples are tested experimentally using the two-microphone impedance tube method and the measured result was compared with the numerical result, which is predicted from COMSOL Multiphysics. The experimental results of flexible foam demonstrate good agreement with numerical results. The results indicate that the addition of Luffa fibers enhances the sound absorption performance of flexible foam and deterioration in the rigid foam because of the high viscosity of castor oil polyol.

Graphical Abstract

  • Bio-based polyurethane foam developed with castor polyol and Luffa fiber for acoustic application.
  • Incorporation of fibers enhances the sound absorption capability of Pu foam.
  • Morphological study evident the presence of Luffa fiber in foam sample.
  • Powder form of fiber can be used as filler rather than short fiber would be better for rigid foam.
  • Flow resistivity of open cell foam increases with addition more fibers.

Keywords: polyurethane foam, luffa fiber, impedance tube, COMSOL Multiphysics, sound absorption coefficient.


We would like to thank the Department of Science and Technology (DST-SERB; File No. ECR/2015/000111) for providing us the necessary facilities and funds for conducting this study.


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