Polymers based on N,N‐diglycidylaniline. I. Investigations of the curing kinetics by dynamic differential scanning calorimetry measurements

Abstract

N,N‐Diglycidylaniline was reacted with aniline (yielding polymer EP‐1) and the newly synthesized chromophore 4‐(phenylazo)aniline (yielding polymer EP‐2). The curing kinetics of these two epoxy resin systems was studied in dynamic experiments by means of differential scanning calorimetry. Kinetic parameters such as the activation energy and frequency factor were estimated with the Ozawa method [E(O) and A(O), respectively], the Kissinger method [E(K) and A(K), respectively], and the modified Avrami method [E(A) and A(A), respectively]. The activation energy and frequency factor of EP‐1 were much lower than those of EP‐2 estimated with the Ozawa, Kissinger, and Avrami methods. The activation energy and frequency factor for EP‐1 determined with the Ozawa method [E(O) = 55.8 kJ/mol, A(O) = 10 × 103 1/s] and the Avrami method [E(A) = 56.4 kJ/mol, A(A) = 9.2 × 103 1/s] were higher than those determined with the Kissinger method [E(K) = 51.0 kJ/mol, A(K) = 2 × 103 1/s]. In the case of EP‐2, the kinetic parameters calculated with the Ozawa model [E(O) = 140.4 kJ/mol, A(O) = 12.3 × 1013 1/s] and the Kissinger model [E(K) = 139.9 kJ/mol, A(K) = 10.9 × 1013 1/s] were higher than those calculated with the Avrami model [E(A) = 130.4 kJ/mol, A(A) = 7.9 × 1012 1/s]. The obtained polymers were characterized with Fourier transform infrared, 1H‐NMR, differential scanning calorimetry, and ultraviolet–visible spectroscopy. The polymers exhibited low glass‐transition temperatures in the range of 57–79°C and good solubility in common organic solvents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Influence of azobenzene units on imidization kinetic of novel poly(ester amic acid)s and polymers properties before and after cyclodehydration

“…In this study, the dynamic DSC experiments were carried out to investigate the conversion of novel poly(ester amic acid)s (PAA) with azobenzene units as side groups to corresponding poly(esterimide)s (PESI). In this work, the experimental DSC results were analyzed by Ozawa and Kissinger models 22, 23–30. These methods, in which the system is cured on various heating rates, are simple and valuable for the study of cure kinetics.…”

“…In this work, the experimental DSC results were analyzed by Ozawa and Kissinger models. 22,[23][24][25][26][27][28][29][30] These methods, in which the system is cured on various heating rates, are simple and valuable for the study of cure kinetics. The objective of this work were (1) the determination of the activation energy (E) and the frequency factor (A) of reaction imidization of novel PAA with azobenzene moieties, (2) comparison of the kinetic parameters estimated by different models, and (3) investigation of chosen polymer properties important for further applications such as: solubility, thermal, and optical properties.…”

Molecular modeling of epoxide-amine systems: Topological cure conversion limit and its influence on material properties

“…Experimental techniques such as Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) are commonly used to monitor the physical change in resin-hardener compound in terms of the extent of conversion X [1][2][3][4][5][6][7][8][9][10]. In FTIR, the changes in spectral features, such as the intensity of the epoxide group are utilized to calculate the extent of conversion using the following:…”

“…One way is to divide the heat released ( ) t H ∆ ∆ ∆ ∆ from the sample up to a time t by the total reaction heat 0 H ∆ ∆ ∆ ∆ [5][6][7] as follows:…”

Problems with Applying the Ozawa–Avrami Crystallization Model to Non-Isothermal Crosslinking Polymerization

“…Ozawa makes no mention of using this function for determining the activation energy. The idea of such a usage takes its origin from a paper by Lu et al [21] and is actively being pursued by other scholars [22][23][24][25][26][27].…”