Curing of epoxy resins with dicyandiamide

Fedtke, M.; Domaratius, F.; Walter, Karolin; Pfitzmann, A.

doi:10.1007/bf00329879

Cited by 18 publications

(12 citation statements)

References 14 publications

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“…The intensity of the band at 915 cm −1 is moderate and can serve as a measure of the extent of the curing reaction, i.e., opening of glycidoxy rings and their crosslinking into polymeric materials [28]. The spectrum of D formulation, in addition to vibrations of DGEBA, shows the stretching of primary and secondary amines (ν(NH 2 ), ν(NH)) between 3430 and 3150 cm −1 and cyano group at 2208 and 2162 cm −1 [33] ( Figure 4A). When DGEBA is in part exchanged with GlyPOSS, i.e., for D-P formulation, the spectrum retains the basic characteristics of amino and cyano groups ( Figure 4A).…”

Section: Temperature-dependent Ft-ir Spectramentioning

confidence: 99%

Tailored Crosslinking Process and Protective Efficiency of Epoxy Coatings Containing Glycidyl-POSS

et al. 2020

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Versatile product protective coatings that deliver faster drying times and shorter minimum overcoat intervals that enable curing at faster line speeds and though lower energy consumption are often desired by coating manufacturers. Product protective coatings, based on silsesquioxane-modified diglycidyl ether of bisphenol-A (DGEBA) epoxy resin, are prepared through a glycidyl ring-opening polymerization using dicyandiamide (DICY) as a curing agent. As silsesquioxane modifier serves the octaglycidyl-polyhedral oligomeric silsesquioxane (GlyPOSS). To decrease the operational temperature of the curing processes, three different accelerators for crosslinking are tested, i.e., N,N-benzyl dimethylamine, 2-methylimidazole, and commercial Curezol 2MZ-A. Differential scanning calorimetry, temperature-dependent FT-IR spectroscopy, and rheology allow differentiation among accelerators’ effectiveness according to their structure. The former only contributed to epoxy ring-opening, while the latter two, besides participate in crosslinking. The surface roughness of the protective coatings on aluminum alloy substrate decreases when the accelerators are applied. The scanning electron microscopy (SEM) confirms that coatings with accelerators are more homogeneous. The protective efficiency is tested with a potentiodynamic polarization technique in 0.5 M NaCl electrolyte. All coatings containing GlyPOSS, either without or with accelerators, reveal superior protective efficiency compared to neat DGEBA/DICY coating.

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Section: Temperature-dependent Ft-ir Spectramentioning

confidence: 99%

Tailored Crosslinking Process and Protective Efficiency of Epoxy Coatings Containing Glycidyl-POSS

et al. 2020

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“…Such a so‐called “epoxy‐DICY” system gives cured products with excellent mechanical and electrical properties 1–4. The curing system involves many reaction pathways, and some of them were clarified by structural analyses of the intermediates by NMR, IR, MS, and HPLC 5–8. For example, the nucleophilic attack of NH 2 of DICY to epoxide results in the ring‐opening reaction to give the corresponding adduct with hydroxyl group, and this hydroxyl group can react further with cyano group of DICY‐derived molecules to increase crosslinking density.…”

Section: Introductionmentioning

confidence: 99%

Efficient accelerating effect of carbonyldiimidazole on epoxy‐dicyandiamide curing system

Liu

Sudo

Endō

2010

J. Polym. Sci. A Polym. Chem.

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Carbonyldiimidazole (CDI) was inventively used as an accelerator for the curing reaction of diglycidyl ether of bisphenol A (DGEBA) with dicyandiamide (DICY) and a high acceleration more effective than imidazole in double usage was observed. This result implies the accelerating role of CDI in the curing process is complex and involved not only the release of imidazole. To detail the accelerating mechanism of CDI, a series of curing reactions was studied by differential scanning calorimetry (DSC), NMR, IR, and viscosity monitoring. The results suggested that the accelerating mechanism of CDI involves (1) acylation of DICY with CDI to give the corresponding adduct with enhanced solubility, (2) the consequent release of imidazole that can react with epoxide, and (3) abstraction of proton of DICY by the alkoxide moiety to give the corresponding DICY anion endowed with enhanced nucleophilicity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

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“…7). The oxirane rings react with the amine groups [8,11,[26][27][28][29][30][31][32][33][34][35]. At some temperature, their consumption exceeds the supply of Dicy molecules from the dissolving particles.…”

Section: Curing Of Ep Accel and Ep N-filledmentioning

confidence: 99%

“…Hydroxyl groups appear as the result of that addition reaction. They provide the reaction partner for the nitrile groups[8,11,[26][27][28][29][30][31][32][33][34][35]] -Figure 10.…”

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confidence: 99%

Functional nano fillers in epoxy-dicyandiamide adhesives for prolonged shelf life and efficient cure

Gaukler¹,

Müller²,

Krüger³

et al. 2016

Nano Online

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Shelf life at room temperature and curing behaviour at elevated temperature are studied for hot-curing accelerated epoxies (EP, diglycidylether of bisphenol A plus dicyandiamide (Dicy)) by FTIR-spectroscopy and modulated DSC. The accelerator is added either directly or with nano-zeolite filler to the EP. Due to the immobilisation of the accelerator in the pores of the nano-zeolite, the shelf life of this EP is 5 times longer than for the EP containing free accelerator. While the free accelerator acts during the whole heating step to curing temperature, the nano-zeolite does not release the accelerator before ca. 100 °C. As monitored by light microscopy, the released accelerator not only supports the curing but also stimulates the dissolution of the solid Dicy. As the result, network formation at 170 °C finishes within less than 25 minutes for the nano-filled EP.Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.

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Curing of epoxy resins with dicyandiamide

Cited by 18 publications

References 14 publications

Tailored Crosslinking Process and Protective Efficiency of Epoxy Coatings Containing Glycidyl-POSS

Tailored Crosslinking Process and Protective Efficiency of Epoxy Coatings Containing Glycidyl-POSS

Efficient accelerating effect of carbonyldiimidazole on epoxy‐dicyandiamide curing system

Functional nano fillers in epoxy-dicyandiamide adhesives for prolonged shelf life and efficient cure

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