Long aging time thermal degradation of the ac conductivity and complex permittivity of conducting polypyrrole

• Published in: Synthetic metals 2011-07, Vol.161 (13), p.1259-1263
• Main Authors: Sakellis, I., Papathanassiou, A.N., Grammatikakis, J.
• Format: Article
• Language: English
• Subjects: ac-conductivity; Ageing; Aging; Annealing; Applied sciences; Complex permittivity; Conducting polymers; Conduction; Degradation; Dielectric loss; Evolution; Exact sciences and technology; Physical properties; Polymer industry, paints, wood; Polypyrrole; Polypyrroles; Properties and testing; Technology of polymers; Thermal aging; Thermal degradation
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2011.04.020

► The dispersive region of the dc conductivity of conducting polypyrrole is practically invariant to one year thermal ageing. ► Cross-over frequency links to the dc conductivity. ► Dielectric loss peak splits into two components within two years thermal ageing. The modification of the ac conductivity and the complex permittivity of conducting polypyrrole was monitored throughout a two years thermal aging at 343 K. Reduction of the cross-over frequency is correlated with the degradation of dc-conductivity, while the ac conductivity region corresponding to the so-called ‘universal’ dielectric relaxation remains practically insensitive during the first year of ageing, which implies a collective co-operativity among multiple degradation processes that yield a practically time-independent effective disordered environment. A broad dielectric loss peak recorded in fresh specimens splits into two distinct relaxations for intermediate stages of the annealing process. The aging-time evolution of the dc component and the relaxations are qualitatively analysed and time constants are determined.