Thermal crosslinking behavior of poly (aryl ether ketone) copolymers containing naphthalene moieties

Abstract

A series of poly[(ether ether ketone)‐co‐(ether naphthalene ether ketone)] (P(EEK‐co‐ENEK)) copolymers were heated under a variety of conditions. The thermal crosslinking behavior was monitored by differential scanning calorimetry (DSC), electron spin resonance (ESR) and wide‐angle X‐ray diffraction (WAXD). The results indicate that under a non‐oxidative environment such as nitrogen P(EEK‐co‐ENEK) is more stable, while under oxidative conditions a crosslinking reaction takes place that causes a reduction in the crystallizability of the copolymers, and an increase in the concentration of free radicals on the copolymer. ESR results suggest that the crosslinking reaction proceeds via free radicals. Subsequently two kinds of free radicals were characterized: one is an RO• type free radical and the other is a naphthalene ring free radical. Copyright © 2004 Society of Chemical Industry

Optimizing high-temperature capacitive energy storage performance by constructing crosslinked structure in self-crosslinkable polyetherimides

“…From the GPC results, it is known that with the increase of heating temperature, Mw will decrease at high temperatures, which may be caused by the chain scission to generate additional RO•. Furthermore, with the increase of temperature, we observed a gradual change of the ESR peak type of the crosslinked polymers from asymmetric to symmetric spectrum, which is consistent with the ESR spectral characteristics of RO• with rigid molecular structures [3]. This further confirms the presence of RO• in the crosslinked polymer.…”

Thermal degradation kinetics and lifetime prediction of poly(aryl ether ketone)s containing 2,6‐naphthalene moieties

“…From the integration of eq. (2), the lifetime ( t f ) can be estimated by or n can be obtained directly from the symmetrical index of a DTG peak based on the second Kissinger technique:6 where the subscripts L and R correspond to the left and right peak ( d 2α/ dt 2 ) values on the second derivative thermogravimetry (2DTG) curves. If we assume that PANEK occurs at α = 0.05, the lifetime can be estimated with eq.…”

“…Along with the development of the science and technology, people have attempted to obtain materials with higher temperature classifications and more excellent thermal performances. To improve the performance of poly(aryl ether ketone)s further and fulfill the requirements of some extreme environmental conditions, such as high temperatures, naphthalene rings have been introduced into polymer structures by some researchers because they have a larger volume than benzene rings; they can enlarge the proportion of rigid groups in the main chain, decrease the mobility of the segments, and therefore increase the glass‐transition temperature of a polymer 1–4…”

Rational Design of Soluble Polyaramid for High‐Efficiency Energy Storage Dielectric Materials at Elevated Temperatures

“…It can be seen from Figure S3, Supporting Information, that a significant peak appears at 272 °C, and this represents the beginning of a phase transition in the polymer film. In our research group's previous work, Niu et al [ 29 ] have studied the reaction between naphthalene rings at high temperature in air. They have proven that when the naphthalene rings are exposed to oxygen, a cross‐linking reaction would take place at temperatures above 260 °C.…”