Epoxy/layered double hydroxide (LDH) nanocomposites: Synthesis, characterization, and Excellent cure feature of nitrate anion intercalated Zn-Al LDH

• Published in: Progress in organic coatings 2019-11, Vol.136, p.105218, Article 105218
• Main Authors: Karami, Zohre, Jouyandeh, Maryam, Ali, Jagar A., Ganjali, Mohammad Reza, Aghazadeh, Mustafa, Paran, Seyed Mohammad Reza, Naderi, Ghasem, Puglia, Debora, Saeb, Mohammad Reza
• Format: Article
• Language: English
• Subjects: Aluminum; Anions; Cure index; Curing; Differential scanning calorimetry; Epoxy; Epoxy resins; Fourier transforms; Heating rate; Hydroxides; Infrared analysis; Infrared spectrophotometers; Interlayers; Layered double hydroxide; Lewis acid; Nanocomposites; Nanoparticles; Nitrate ion; Nitrates; Spectrophotometry; Synthesis; Thermogravimetric analysis; Thermosetting resins; Zinc; Zn-Al-LDH
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2019.105218

•Synthesized and characetrized Zn-Al LDH intercalated with nitrate anion, Zn-Al-NO3.•Fully characetrized Zn-Al-NO3 with FTIR, TGA, and XRD analyses.•Epoxy/Zn-Al-NO3 nanocomposites underwent dynamic DSC at various heating rates.•Cure Index revealed Excellent cure for epoxy/Zn-Al-NO3 nanocomposites. Layered double hydroxides (LDHs) belong to two-dimensional (2D) nanoparticle family. Best known as anionic clays, LDHs were the promising choice for a wide range of applications. Despite the widespread research on synthesis and application of LDH as an additive in thermoset resins, a few was known about its curing ability. In this work, Zn-Al LDH intercalated with nitrate anion (Zn-Al-NO3) was synthesized, characterized and incorporated into epoxy resin at low content of 0.1 wt.%. Fourier-transform infrared spectrophotometry (FTIR), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA/DTG) techniques were employed to characterize LDH. Nonisothermal differential scanning calorimetry (DSC) at different heating rates allowed for evaluating curing state of epoxy/Zn-Al-NO3 LDH nanocomposites containing 0.1 wt.% of LDH in terms of Cure Index universal criterion. Zn-Al-NO3 LDH assisted epoxy in curring with an amine precursor resulting in much more heat release in a shorter curing temperature interval with respect to the blank epoxy system whatever heating rate. Such promising feature was signaled by Excellent cure state demonstrated by Cure Index, which was attributed to Lewis acid effect of Zn that catalyzed epoxy curing reaction. Moreover, it was discussed that an enlarged LDH interlayer space brought about by incorporation of nitrate anion between layers facilitated the curing reaction.