Dielectric properties of trans‐1,4 polybutadiene

Measurements were made of the dielectric constant and of tg δ of trans‐1,4‐polybutadiene with a steric purity higher than 99% at a constant frequency of 50 c.p.s. and at variable temperatures between −50° and +170°C. The behaviour of the dielectric constants points out a first order transition at 76°C., corresponding to the known variation of conformation of the crystalline chain, and another first order transition at 146°C., corresponding to the complete melting. The values of tg δ are of the order of 10−3 up to the first transition, then they increase considerably due to the increase in electric conductivity.