Dielectric relaxations in polyoxymethylene and in related nanocomposites: Identification and molecular dynamics

POLYMER

卷:55

Article

Karahaliou, P. K.¹  Kerasidou, A. P.¹  Georga, S. N.¹  Psarras, G. C.²  Krontiras, C. A.¹  Karger-Kocsis, J.^3,4 

[1] Univ Patras, Dept Phys, Patras 26504, Greece

[2] Univ Patras, Dept Mat Sci, Patras 26504, Greece

[3] Budapest Univ Technol & Econ, Dept Polymer Engn, H-1111 Budapest, Hungary

[4] MTA BME Res Grp Composite Sci & Technol, H-1111 Budapest, Hungary

关键词: Polyoxymethylene;    Dielectric relaxation;    Nanocomposites;   

DOI  :  10.1016/j.polymer.2014.10.056

来源: Elsevier

【 摘 要 】

Broadband dielectric spectroscopy (BDS) is employed for the study of the dielectric response of Polyoxymethylene/boehmite alumina (POM/alumina) and Polyoxymethylene/Layered Silicates (POM/LS) semi-crystalline nanocomposites, together with the response of pure POM. The compilation of the dielectric responses of all systems reveals the existence of five dielectric relaxation mechanisms assigned, in terms of decreasing temperature at constant frequency, as IP (interfacial polarization), alpha-, beta-, gamma- and delta-relaxations. IP, alpha- and gamma-relaxations are detected in all studied systems and they are well documented in the literature. delta-relaxation, been the fastest mechanism, is present only in the POM/LS system and is associated with defect dipoles in the crystalline phase of POM. Finally, beta-relaxation is present only in the POM/alumina nanocomposite and its dynamics obey Vogel-Fulcher-Tamann temperature dependence. This work presents a complete mapping of the dielectric relaxation mechanisms of POM and signifies the connection of beta-mode with the glass to rubber transition of POM, confirming its cooperative character. (C) 2014 Elsevier Ltd. All rights reserved.

【 授权许可】

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