T.S.C. study of liquid-liquid transition in polyvinyl chloride

The thermally stimulated current (T.S.C.) diagrams have been recorded above 0°C, with samples obtained by pelleting under a pressure of 3.5 T/cm², the PVC powder. These T.S.C diagrams, obtained with conditions of polarization T_p=125°C, tp=2 min., F_p=3.10⁵ V/m, have shown at 80°C. In the neighbourhood of the glass transition, a first peak with a shoulder towards 55°C. A second peak, associated to a liquid-liquid transition appears at 123°C. The ratio T_ll(°K)/Tg(°K)=1.13 is close to those obtained with different polymers by different authors. The T_ll follows a Vogel-W.L.F. law τ=τ₀exp(α_r(T-∞))^-1 where T_∞=304°K