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Synthesis, Characterization, and Properties of POSS-Epoxy

11/01/2016 · Robust synthesis of epoxy resin-filled microcapsules for application to self-healing materials

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Synthesis and Properties of a Bio-Based Epoxy Resin …

Many research efforts have focused on replacing BPA in epoxy resins. Renewable resource based polymers, including materials derived from starch, cellulose, vegetable oil, and natural occurring phenols, have demonstrated their potential to replace petrochemical products. In particular, natural polyphenols, which are abundant in biomass, are structurally similar to many building blocks of thermosetting resins. These natural polyphenols could potentially be a resource for epoxy and benzoxazine resins, contributing to properties comparable to oil based bisphenols (Maffezzoli et al. 2004; Calò et al. 2007; Benyahya et al. 2014; Chen et al 2015; Niedermann et al. 2015). This includes lignins co-produced during papermaking, which are formulated with epoxy networks and cross-linked by direct heating (Hofman and Glasser 1994). Tannins are another source of natural polyphenols, exhibiting wide structural diversity and generally having more than two phenolic hydroxyl groups. Flavonoids such as resorcinol, catechol, and catechin can be glycosylated by epichlorohydrin to prepare aromatic-based epoxy resins (Nouailhas et al2011). Gallic acid is a phenolic acid that occurs freely or as a part of gallotannins in different plants. These structures contain three phenolic hydroxyl groups and one carboxylic moiety, which can be used to obtain new bio-based epoxy thermosetting resins. Aouf et al. (2013) synthesized gallic acid-based epoxy resins that were then cured with a diamine to yield a cross-linked material. The thermal properties of the resulting epoxy network were compared with standard BPA-based epoxy resins. In another recent study, an epoxy resin based on gallic acid and a formaldehyde resin were synthesized as matrix of a glass fiber composite material (Chen et al.2015). Additionally, Hou et al. (2016) prepared bio-based epoxy resins from renewable gallic acid; the resulting bio-based nanocomposite and glass fiber-reinforced composite was formulated with succinic anhydride as a curing agent.

Research in Area of Materials Science: Synthesis, Characterization, and Properties of POSS-Epoxy

An aromatic epoxy monomer, formed by glycidylation of gallic acid, was crosslinked by adopting different curing agents to obtain bio-based, crosslinked resins with suitable engineering properties. Specifically, tri- and tetra-glycidyl ether of gallic acid (GEGA) were obtained using a two-step synthesis. These bio-based monomers were cured in the following three epoxy formulations: a stiff cycloaliphatic primary amine, isophorone diamine, and a flexible polypropylene oxide amine (Jeffamine D-230). Next, the homopolymerization of GEGA was studied using an ionic initiator, N,N-dimethylbenzylamine, and a complex curing mechanism highlighted by calorimetric and mass spectra analysis. Calorimetric and rheological measurements were used to compare the curing behavior of the studied GEGA-based formulations. Mechanical properties of the gallic acid-based epoxy resins were comparable with those of standard epoxy resin formulations, based on di-glycidyl ether of bisphenol A. Thermogravimetric analysis of cured samples showed a relevant char content at high temperatures.

Synthesis and properties of a bio-based epoxy resin …

Synthesis and characterization of thianthrene-based epoxy with high refractive index over 1.7

An aromatic epoxy monomer, formed by glycidylation of gallic acid, was crosslinked by adopting different curing agents to obtain bio-based, crosslinked resins with suitable engineering properties. Specifically, tri- and tetra-glycidyl ether of gallic acid (GEGA) were obtained using a two-step synthesis. These bio-based monomers were cured in the following three epoxy formulations: a stiff cycloaliphatic primary amine, isophorone diamine, and a flexible polypropylene oxide amine (Jeffamine D-230). Next, the homopolymerization of GEGA was studied using an ionic initiator, N,N-dimethylbenzylamine, and a complex curing mechanism highlighted by calorimetric and mass spectra analysis. Calorimetric and rheological measurements were used to compare the curing behavior of the studied GEGA-based formulations. Mechanical properties of the gallic acid-based epoxy resins were comparable with those of standard epoxy resin formulations, based on di-glycidyl ether of bisphenol A. Thermogravimetric analysis of cured samples showed a relevant char content at high temperatures.

In this study, gallic acid glycidylation was performed by slightly modifying the two-step chemical synthesis reported by Aouf et al. (2013). Tri- and tetra-glycidyl ethers of gallic acid were obtained, and their chemical structures were characterized. These bio-based epoxides were used to formulate three different model systems as curing agents, a stiff cycloaliphatic primary amine, isophorone diamine (IPDA), and a flexible polypropylene oxide amine, Jeffamine D-230 (DPG). These renewable epoxides were homopolymerized using N,N-dimethylbenzylamine (BDMA) as an ionic initiator (Dell’Erba and Williams 2006). The thermal, rheological, and mechanical properties of the gallic acid-based epoxy resins were characterized and compared with standard DGEBA-based formulations. The results showed that the GEGA structure is suitable to replace BPA-based epoxy resins.

Synthesis of bisphenol a novolac epoxy resins for …

Vanillyl alcohol, a lignin derived aromatic diol, is a potential platform chemical for the production of renewable epoxy thermosets. A bio-based bisphenolic analogue, bisguaiacol (BG), was synthesized via electrophilic aromatic condensation of vanillyl alcohol and guaiacol, from which diglycidyl ether of BG (DGEBG) was prepared. In addition, three single aromatic diglycidyl ethers were synthesized from vanillyl alcohol (DGEVA), gastrodigenin (DGEGD), and hydroquinone (DGEHQ). All epoxies were characterized via 1H NMR, 13C NMR, FTIR, MS, and GPC. Dynamic mechanical analyses of the epoxies by themselves or blended with a commercial epoxy resin and cured with a diamine were conducted to determine the effect of the methoxy and methylene moieties on polymer properties. The thermomechanical results indicate that the methoxy lowers the glass transition temperature (g) yet increases the glassy storage modulus at 25 °C, while the methylene spacer between the aromatic ring and the epoxide further lowers the g in cured epoxy–amine systems.

1H NMR, 13C NMR, and GPC traces of monomers and epoxy resins synthesized in this work as well as DMA and TGA thermograms of cured epoxy–amine systems ()

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Manufacturing Process of Epoxy Resins with …

Nouailhas, H., Aouf, C., Le Guerneve, C. L., Caillol, S., Boutevin, B. and Fulcrand, H., (2011). “Synthesis and properties of biobased epoxy resins. Part 1: Glycidylation of flavonoids by epichlorohydrin,” Journal of Polymer Science Part A: Polymer Chemistry 49(10), 2261-2270. DOI: 10.1002/pola.24659

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