Flexible Acoustic Polyurethane Foam: An Overview of Physical Structure and Chemical Properties

Noise is one of the most disturbing environmental problems of today's societies, and this problem becomes more serious with increasing traffic volumes and rapid expansion of industries. One of the ways to solve this problem is to increase the sound absorption coefficient of porous structure materials used as acoustic absorbers. Over the past decade, flexible polyurethane foam has been recognized in the acoustic absorbing industry as efficient materials due to its effective damping power, low density, high formability and easy production. The most important feature of flexible polyurethane foams is the presence of open porosity cavities, which not only control the mechanical properties of foam, but also their sound insulation properties. The purpose of this study is to review the applications, the development of polyurethane foam, the chemical and physical structure and the factors affecting the properties of foams due to their acoustic absorption and mechanical energy loss of sound waves. Considering the role of polyurethane foam as sound insulation, the focus of this study will be on the behavior of polyurethane foam as sound insulation, so some physical concepts related to sound will also be expressed.