Dynamic rheological behavior of poly(ether ketone ketone) from solid state to melt state

Abstract

High performance thermoplastic poly(ether ketone ketone) (PEKK) polymers with various meta phenyl links ratio were investigated by dynamical mechanical analysis. Analyses were carried out in a wide range of temperature from solid state (torsion rectangular mode) to the melt state (torsion parallel plates mode) as function of thermal history and environmental conditions. In the solid state, this study was focused on the secondary relaxations in the vitreous state. A complementary investigation conducted with different poly(aryl ether ketones) allowed us to propose a molecular interpretation of PEKK sub‐vitreous relaxations. In the molten state, storage modulus (G′), loss modulus (G″), storage viscosity (η′), and loss viscosity (η″) were studied to determine zero shear‐rate viscosity (η0) and thermal activation energy Ea. Master curves were built and the shift factor aT was determined. Thermal activation energies were extracted from an Arrhenius model on the shift factor temperature's dependency. Finally, Ea and η0 were determined thanks to the dynamic viscosity fit with Cross model and Cole–Cole representation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46456.

Influence of electronic irradiations on the chemical and structural properties of PEEK for space applications

“…At low temperature, the broad peak at about À90 C is labelled g relaxation. It has been associated in the literature with dipolar entities which can interact with water like ketone groups present on the main chain [34,35]. Literature also highlights another secondary relaxation named b, located at around À60 C, associated with the oscillation of phenyl groups around their axis.…”

Electronic irradiation ageing in the vicinity of glass transition temperature for PEEK space applications

“…At low temperature, the γ relaxation is associated with localised mobility of polar groups. Studies have concluded that this relaxation is allowed by the presence of water molecules absorbed in the polymer [32,33]. At higher temperature, the relaxation named α is associated with the mechanical manifestation of the glass transition.…”

Influence of composite preform fabrication on the integrity of poly‐aryl‐ether‐ketone matrices

“…25,26,27,28 The consequence of these chemical reactions is a modification of the molecular weight, 26 but also modifications of the physical and mechanical properties like the crystallization behavior, melting and glass transition temperatures as well as modulus. 29,30,31,32 In particular, the crosslinking process results in a rapid increase of the polymer viscosity, 30,32,33 which has a detrimental effect on the resin flow during the preform consolidation. Phillips et al demonstrated for instance that the impregnation of a carbon reinforcement with PEEK films is strongly reduced after a heat treatment of a few seconds at 400 C. 34 Therefore, the probability that the properties of PAEK matrices are modified during the fabrication of composite preforms is not negligible.…”