Dielectric Property of Some Polymers in Low Temperature Region

Abstract

Measurements of the dielectric property of various polymers are made at temperatures from -268°C to 20°C at various frequencies. Loss peaks are observed at -130°C (f=300 H _z ) for oxidized polyethylene, at -110°C (3 kHz) for oxidized polypropylene, at -59°C (3 kH _z ) for poly-bisphenol-A-carbonate, at -50°C (3 kHz) for ploy-tetrachlorobis-phenol-A carbonate and at -75°C (3 kHz) for cyanoethylcellulose, respectively. The absorptions are attributed to local mode relaxations in amorphous region, No distinct loss maxima are observed below these temperatures. An upswing of loss tangent is found in the vicinity of liquid helium temperature for poly-methylemthacrylate.