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Open AccessArticle

Kinetics of Cross-Linking Reaction of Epoxy Resin with Hydroxyapatite-Functionalized Layered Double Hydroxides

Center of Excellence in Electrochemistry, School of Chemistry, College of Science, University of Tehran, P.O. Box 11155-4563, Tehran, Iran
Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, P. O. Box 11155-4563, Tehran, Iran
School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran
Department of Chemical Engineering, School of Engineering Technology and Industrial Trades, College of the North Atlantic-Qatar, 24449 Arab League St, P.O. Box 24449, Doha, Qatar
Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), P.O. Box 15875-4413, Tehran, Iran
College of Engineering and Technology, American University of the Middle East, 15453 Egaila, Kuwait
Advanced Functional Materials Laboratory, Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, India
Department of Polymer Technology, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80–233 Gdańsk, Poland
Department of Resin and Additives, Institute for Color Science and Technology, P.O. Box 16765-654, Tehran, Iran
Authors to whom correspondence should be addressed.
Polymers 2020, 12(5), 1157;
Received: 27 April 2020 / Revised: 11 May 2020 / Accepted: 15 May 2020 / Published: 18 May 2020
(This article belongs to the Special Issue Epoxy Resins and Composites)
The cure kinetics analysis of thermoset polymer composites gives useful information about their properties. In this work, two types of layered double hydroxide (LDH) consisting of Mg2+ and Zn2+ as divalent metal ions and CO32− as an anion intercalating agent were synthesized and functionalized with hydroxyapatite (HA) to make a potential thermal resistant nanocomposite. The curing potential of the synthesized nanoplatelets in the epoxy resin was then studied, both qualitatively and quantitatively, in terms of the Cure Index as well as using isoconversional methods, working on the basis of nonisothermal differential scanning calorimetry (DSC) data. Fourier transform infrared spectroscopy (FTIR) was used along with X-ray diffraction (XRD) and thermogravimetric analysis (TGA) to characterize the obtained LDH structures. The FTIR band at 3542 cm−1 corresponded to the O–H stretching vibration of the interlayer water molecules, while the weak band observed at 1640 cm−1 was attributed to the bending vibration of the H–O of the interlayer water. The characteristic band of carbonated hydroxyapatite was observed at 1456 cm−1. In the XRD patterns, the well-defined (00l) reflections, i.e., (003), (006), and (110), supported LDH basal reflections. Nanocomposites prepared at 0.1 wt % were examined for curing potential by the Cure Index as a qualitative criterion that elucidated a Poor cure state for epoxy/LDH nanocomposites. Moreover, the curing kinetics parameters including the activation energy (Eα), reaction order, and the frequency factor were computed using the Friedman and Kissinger–Akahira–Sunose (KAS) isoconversional methods. The evolution of Eα confirmed the inhibitory role of the LDH in the crosslinking reactions. The average value of Eα for the neat epoxy was 54.37 kJ/mol based on the KAS method, whereas the average values were 59.94 and 59.05 kJ/mol for the epoxy containing Zn-Al-CO3-HA and Mg Zn-Al-CO3-HA, respectively. Overall, it was concluded that the developed LDH structures hindered the epoxy curing reactions. View Full-Text
Keywords: cure index; epoxy; layered double hydroxide (LDH); hydroxyapatite; curing kinetics; isoconversional methods cure index; epoxy; layered double hydroxide (LDH); hydroxyapatite; curing kinetics; isoconversional methods
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Karami, Z.; Ganjali, M.R.; Zarghami Dehaghani, M.; Aghazadeh, M.; Jouyandeh, M.; Esmaeili, A.; Habibzadeh, S.; Mohaddespour, A.; Inamuddin; Formela, K.; Haponiuk, J.T.; Saeb, M.R. Kinetics of Cross-Linking Reaction of Epoxy Resin with Hydroxyapatite-Functionalized Layered Double Hydroxides. Polymers 2020, 12, 1157.

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