The Relationship of the Polymer Molecular Structure and the Dynamic Mechanical Property Under High Pressure

Abstract

The dynamic mechanical properties of the viscoelastic polymer materials are usually considered to be the key parameters for the vibration damping or acoustic materials. The relationship between the molecular structures of the random copolymer butadiene styrene rubber (SBR) obtained through the anionic polymerization method and their dynamic mechanical parameters under high pressure is studied to explore the energy loss mechanism of the polymer materials applied in the special conditions such as high pressure. The dynamic mechanical parameters were tested though experimental methods with pressure chambers, which can supply high pressure to the polymer samples. The results show that the most important effect factor of the molecular structure is the ratio of the content of the stiffer segments composed of styrene in the SSBR molecular chain to the softer ones composed of 1, 4-butadiene. This can be attributed to the stiffer segments supplying bigger free volumes for the molecular motion and higher modulus to resist to the high pressure, and the softer segments endue the effective energy loss ability to the polymer chains. However, the mass ratio of the stiffer and softer segments should be in an appropriate range, which the content of the styrene must be less than 40%.