Molecular Design And Damping Properties Of Polyurethane Elastomer

Damping materials were novel functional materials that were efficient in converting sound and mechanical vibration energy into heat that resulted in absorption. Polymers had been used in sound and vibration damping areas since 1950s.Polyurethanes were particularly attractive for a study of the effect of chemical structure on damping because it was possible to change their glass transitions over a wide range of temperature by transform of the ratio of hard and soft segments. According to the results of previous studies one of the major methods to improve damping properties was to design macromolecular polymer structure. Another one was IPN technique. However, the two methods just affected damping properties in temperature range of glass transitions.A new concept of hung-chain structure was put forward in this paper after carefully reading literature and former work. For the hung-chain with 8-18 C was introduced into main chain of polyurethane, dynamic mechanical characters of PU was improved. This was regarded as plastic friction between hung-chain and main cross linked chain structure. In this paper, a novel damping material was prepared by adding a kind of diol chain extender with hung-chain structure into polyurethane. The effects of the kind and mass fraction of hard segment as well as cross linker on the dynamic viscoelasticity and damping properties of polyurethane were studied in detail. The results showed that the damping properties of PU were improved considerably when a diol chain extender was introduced into the molecule and the damping factory of temperature range above Tg was increased in evidence. Hung-chain structure chain extender could broaden the temperature range. It could engender a large platform area during 30-80℃in which damping factor was higher than 0.4.It was also proved that proper hindered phenol and cross linker could influence damping properties.Performance of PU contained different blended hard segments, TDI and HDI, was discussed in this paper. The results showed that changes in ratio of two kinds of hard segments can be used to control damping properties in a proper temperature range and mechanical properties.