Negative dielectric permittivity of poly(acrylic acid) pressed pellets

Spontaneously formed temperature-frequency zone of negative dielectric permittivity epsilon'< 0 was found in polymer-water system poly(acylic acid) + 3 wt% of moisture. Nucleation and evolution of the zone is demonstrated on epsilon'(f,T), epsilon ''(f,T) and tg delta(f,T) 3D plots. Bound water release at T > 65 degrees C is thought to be the reason of this phenomenon. The frequency width of the zone steadily increases with temperature up to T = 83 degrees C, and then sharply increases at low-frequency side. This effect might be Telated to the anomalies in temperature dependencies of thermodepolarization currents in water at 83 degrees C. Spontaneous manifestation of epsilon' < 0 phenomenon indicates that one can expect it in natural materials, including biopolymers, i.e. in living organisms. (C) 2016 Elsevier B.V. All rights reserved.