Damping properties and transmission loss of polyurethane. I. Effect of soft and hard segment compositions

A series of polyurethane compositions with soft and hard segments were prepared, and the damping and mechanical properties of these materials were studied. The damping of polyurethane was decreased and shifted to the higher temperature with the content of butanediol (BD) used as a chain extender. The mechanical properties such as tensile strength and hardness (shore A) were increased with increasing ED contents. For application in noise reduction, the transmission loss of the mechanical vibration through solid structure was measured by two methods of extensional and constrained layer configuration. Polyurethane was used as a damping layer. The transmission loss of constrained layer configuration was larger than that of extensional configuration. Although the peak tan delta value of polyurethane having composition of ED 0.5 was lower than that of ED 0.4, its transmission loss was more effective at higher frequency. (C) 2000 John Wiley & Sons, Inc.