The dielectric permittivity and loss tangent of 1

2-polybutadienes with different chain structures were determined as a function of temperature from-180℃ to 100℃ at different frequencies

and the frequency and structure dependence of the dielectric propertie of 1

2-polybutadienes have been investigated. It is found that a maximum of the permittivity occurs in the glass-transition region. The width of the glasstransition peak increases with increasing frequency while its height has little change. With a rise in the content of 1

2-units

the permittivity decreases and the height of the glass-transition peak slightly grows.A maximum of the width of the glass-transition peak appears when the content of 1

2-units is about 45%.Both the permittivity and dielectric loss drop down as the growth of the content of syndiotactic 1

2-units.