Damping properties and transmission loss of polyurethane. II. PU layer and copolymer effect

Polyurethane (PU) layer and copolymer consisted of the different molecular weights (1000 and 2000 (g/mol) of poly(propylene glycol) (PPG) were prepared. The damping and mechanical properties of these materials were compared with PU 1000 made by PPG having the molecular weight of 1000 g/mol. The optimum composition of PU2000 used for PU layer and copolymer was diphenylmethane diioscynate (MIC)l)/propylene glycol (PPG)/butanediol (BD) (1/0.3/0.7) based oil the damping and mechanical properties. The damping peak of PU copolymer was higher than those of PU layer and PU 1000 in low temperature range (-30-10degreesC). For application in noise reduction. the transmission loss of the mechanical vibration though solid structure was measured. PU layer and copolymer were used as a damping layer. The transmission loss of PU copolymer was more effective than those of PU layer and PU1000 in the experimental frequency range.