Curing Agents For Epoxy Resins Research Articles

Study on Synthesis of Thoreau-modified 3, 5-Dimethyl-Thioltoluenediamine Used as Epoxy Resin Curing Agent and Its Performance

A novel curing agent Thoreau modified 3, 5-Dimethyl-thioltoluenediamine was synthesized and its molecular structure was characterized by FTIR and DSC. The curing kinetics of a high toughness and low volume shrinkage ratio epoxy system (modified DMTDA/DGEBA) was studied by differential scanning calorimetry (DSC) under noni so thermal conditions. The data were fitted to an order model and autocatalytic model respectively. The results indicate that in order model deviates significantly from experimental data. Malik’s method was used to prove that the curing kinetics of the system concerned follow single-step autocatalytic model, and a “single-point model-free” approach was employed to calculate meaningful kinetic parameters. The DSC curves derived from autocatalytic model gave satisfactory agreement with that of experiment in the range 5K/min∼25K/min. As the heating rate increased, the predicted DSC curves deviated from experimental curves, and the total exothermic enthalpy declined owing to the transition of competition relationship between kinetics control and diffusion control.

Synthesis of Castor Oil‐Derived Decanediamide as a Novel Flexible Asphalt‐Modified Epoxy Resin Curing Agent

AbstractCastor oil‐derived decanediamide, as a novel flexible epoxy curing agent, was synthesized by esterization with methanol and ammonolysis with ammonia. The chemical structure and thermal properties of this novel curing agent were confirmed by Fourier transform infrared spectroscopy (FT‐IR), 1H nuclear magnetic resonance (1H NMR) analysis, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The tensile strength, impact strength, dynamic mechanical properties, and thermal stability of cured epoxy resin were investigated by tensile tests,dynamic mechanical analysis (DMA), and TGA, respectively. The results showed that the prepared decanediamide had a high yield of 85.4%, and the epoxy resin cured by the decanediamide revealed a slight decrease in the mechanical properties and thermal stability, and a longer pot life at high temperature compared with that of a conventional epoxy curing agent. Asphalt as a toughening agent was added into this system, in order to improve the poor brittle resistance of pure epoxy resin, which proved to have good compatibility with this system and improve the brittle resistance effectively. Thus, the decanediamide has a great potential to replace some of current petroleum‐based compounds in the synthesis of epoxy curing agents.

Cationic Catalyst as Latent Curing Agent for Epoxy Resin

1-Benzyl-3-methyl-imidazolium hexafluoroantimonate (BMH) was newly synthesized and characterized with FT-IR, 1H-NMR. We synthesized catalysts fulfill requirements for a rapid cure at a moderately elevated temperature in curing the epoxy resin for neat diglycidyl ether bisphenol A (DGBEA). The cure behavior of this resin was investigated at elevated temperature and cure temperature in the presence of 0.5, 1.0, 2.0 wt% of 1-benzyl-3-methyl-imidazolium hexafluoroantimonate (BMH) by mean of differential scanning calorimeter (DSC). Chemical conversion as function of temperature and amount of BMH (0.5, 1.0, 2.0 wt%) were determined from DSC. It was found that BMH were superior latent thermal catalyst for catinonic curing which have a good thermal stability.

アミン系エポキシ硬化剤について

アミン系エポキシ硬化剤について

Preparation and Application of a New Curing Agent for Epoxy Resin

A new curing agent based on palmitoleic acid methyl ester modified amine (PAMEA) for epoxy resin was synthesized and characterized. Diglycidyl ether of bisphenol A (DGEBA) epoxy resins cured with different content of PAMEA along with diethylenetriamine (DETA) were prepared. The mechanical properties, dynamic mechanical properties, thermal properties, and morphology were investigated. The results indicated that the PAMEA curing agent can improve the impact strength of the cured epoxy resins considerably in comparison with the DETA curing agent, while the modulus and strength of the cured resin can also be improved slightly. When the PAMEA/epoxy resin weight ratio is 30/100, the comprehensive mechanical properties of the cured epoxy resin are optimal; at the same time, the crosslinking density and glass transition temperature of the cured epoxy resin are maximal.

Ortho-Substituted Ortho-Cresol Novolac Resins as an Epoxy Resin Curing Agent

A series of ortho-substituted ortho-cresol novolac resins were synthesized and used as curing agents for epoxy resins. The chemical structures of different ortho-substituted ortho-cresol novolac resins were investigated by many measurements, such as FT-IR, 1H NMR, and 13C NMR. The results indicated that the ortho-cresol novolac resin with the needed proportion of ortho-substitution was synthesized through the adjustment of the reaction conditions. The studies on the curing kinetics of ortho-cresol novolac epoxy resin cured by different ortho-cresol novolac resins showed that the activation energy was reduced with an increase in the proportion of ortho-ortho methylene bridges.

Synthesis of Latent Curing Agent for Epoxy Resin

A new kind of latent curing agent (LCA) for epoxy resin was synthesized by the reaction of Ethylenediamine with Butylacrylate in equal molar ratios, and the chemical structure and thermal property of the LCA were studied with FTIR and TGA, respectively. Moreover, LCA was also used to modify the epoxy sizing agent for high modulus carbon fiber. The results show that the wettability of sized carbon fiber tends to increase due to the increase of the polymer film on the surface of the carbon fiber, and interlaminar shear strength (ILSS) of the sized high modulus carbon fiber/epoxy composites is improved to 78MPa, which is increased by 8.6% compared with the composites reinforced by high modulus carbon fiber with unmodified sizing agent, indicating that using LCA modified epoxy resin as polymer coating for carbon fiber is a feasible method to improve the interfacial performance of high modulus carbon fiber/epoxy composites.

Synthesis and Characterization of a Novel Curing Agent for Epoxy Resin Based on Phosphazene Derivatives

In this work, a novel amine-terminated curing agent for epoxy resin based on hexachlorocyclotriphosphazene (HCCP) was synthesized through two steps of nucleophilic substitution reactions by phenol and 4-aminophenol. Its chemical structure was characterized by 1H-NMR, Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). This curing agent was liquid at room temperature which made it easy to disperse in the epoxy resin. The rheological test showed the viscosity of the pre-polymer fluid decreased as the proportion of the curing agent increased so it improved the process performance. The curing reaction was studied by differential scanning calorimeter (DSC). The novel curing agent had a wider range of curing temperature and relatively lower curing temperature in comparison with the widely-using curing agent 4,4′-Diaminodiphenylmethane (DDM). The wider range of curing temperature helped lower the heat accumulation which was an important factor in curing process.

Synthesis and properties of new polyfunctional curing agents for epoxy resins based on dimerized fatty acid

The synthesis and properties of a number of devised imino(amino)amide derivatives of dimerized fatty acid are described. It is shown that synthesized products exhibit the properties of plasticized curing agents for epoxy resins.

Modified Cyclohexanone-Formaldehyde Resin as an Epoxy Resin Curing Agent

Cyclohexanone-formaldehyde (CHF) resin was brominated and the brominated CHF (BCHF) was then reacted with excess aromatic diamines. The aminated CHF resins designated as ACHFs (modified ketone resin) were characterized and then applied as epoxy resin curing agents. Thus, the curing of the commercial epoxy resin diglycidil ether of bisphenol-A (DGEBA) by ACHFs was monitored by differential scanning calorimetric (DSC), based on the the DSC scans, the glass fiber-reinforced composites of DGEBA-ACHF systems were prepared and characterized by chemical resistivity and mechanical properties.

Novel Piperazinylo Bisaryl Hydrazino-S-Triazine Derivatives and Their Application as Epoxy Resin Curing Agents

Various 2-(4-ethyl-1-piperazinylo)-4,6-bisarylhydrazino-1,3,5-triazine (3a–f) were prepared by the reaction of 2-(4-ethyl-1-piperazinylo)-4,6-dichloro-1,3,5-triazine and various phenyl hydrazine derivatives. All the 3a–f derivatives were characterized by elemental analysis and IR spectral studies. All the 3a–f compounds were screened for microbial activity against gram-positive and gram-negative bacteria. All these derivatives were employed as the epoxy resin curing agent. Thus the curing of the epoxy diglycidyl ether of bisphenol-A (DGEBA) was monitored by differential scanning calorimeter (DSC). Based on DSC parameters and glass-fiber reinforced composites based on DGEBA-3(a-f) systems were prepared and characterized.

Complexes of Lewis Acids with Tris(Halogen)Alkyl Phosphates as New Curing Agents for Epoxy Resins

Complexes of Lewis Acids with Tris(Halogen)Alkyl Phosphates as New Curing Agents for Epoxy Resins

Chemistry of Siloxane Amide as a New Curing Agent for Epoxy Resins: Material Characterization and Properties

AbstractSummary: A novel amine terminated elastomeric siloxane modifier (SA amine) for epoxy networks has been synthesized and characterized. The dual role of SA amine not only as a curing agent and but also as a toughener was studied. Curing studies of conventionally available epoxy resin, diglycidyl ether of bisphenol A (DGEBA) using SA amine along with diamino diphenyl sulfone (DDS) has been carried out. An interesting feature was the complete miscibility of the siloxane oligomer with DGEBA. In addition, the cured laminates were analyzed for thermal, mechanical, and surface morphology and also for their chemical resistance. The thermo mechanical properties were studied using dynamic mechanical analysis. The modified systems showed very high thermal stability. A single glass transition temperature was observed for the modified systems. The moisture resistance of the samples improved notably with the introduction of siloxane into the systems. The modified systems also improved the impact strength of the materials to a greater extent (35–50%) even though there was a small decrease in their tensile properties (12%). The system with maximum SA amine content showed the higher impact strength value and also a higher thermal stability without any phase separation in the morphology.Representation of the crosslinking pattern of the resin systems.magnified imageRepresentation of the crosslinking pattern of the resin systems.

Modified Castor Oil as an Epoxy Resin Curing Agent

A castor oil, an agricultural product, is an unsaturated material. Hence the castor oil is brominated by bromine liquid. The brominated castor oil (BCO) was then reacted with excess of aliphatic diamines viz; ethylene diamine, 1,3‐propane diamine and 1,6‐hexane diamine. The resultant amino functionalized castor oil (ACO) samples were then characterized by elemental analysis, IR spectral study and number of amino groups. All the three ACO samples were then employed for the curing of commercial Brominated epoxy resin. The curing of epoxy resin by ACO was monitored on differential scanning calorimeter (DSC) and based on the DSC study their glass fibre reinforced composites (GRC) were fabricated. The cured samples (i.e. unreinforced) were also subjected to thermo gravimetric analysis (TGA). The chemical, mechanical and electrical properties of the glass fibre reinforced composites (GRC) were also evaluated.

Synthesis of novel flame retardant epoxy hardeners and properties of cured products

Novel flame-retardant curing agents for epoxy resins, [ODOPM–PN] and [ODOPM–MPN], were prepared from phenol formaldehyde novolac (PN), melamine-phenol formaldehyde novolac (MPN) and a reactive 2-(6-oxid-6H-dibenz〈c,e〉 〈1,2〉oxaphosphorin-6-yl)-methanol (ODOPM) while ODOPM was synthesized through the reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and formaldehyde. The compounds (ODOPM–PN and ODOPM–MPN) were used as flame-retardant hardener for o-cresol formaldehyde novolac epoxy (CNE) resin in electronic application. The thermal stability and flame retardancy were determined by thermal gravimetric analysis and UL 94 vertical test. The glass transition temperatures were measured by dynamic mechanical analysis. The phosphorus–nitrogen synergistic effect on flame retardancy combined with the rigid structure of ODOPM have resulted in better flame retardancy, higher glass transition temperature and thermal stability for the phosphorus–nitrogen containing epoxy resin system than the regular phosphorus-containing flame retardant epoxy resin system. UL 94-VO rating could be achieved with a lower phosphorus content of as low as 0.81% with 2.36% nitrogen for the ODOPM–MPN cured epoxy resin system and no fume and toxic gas emission were observed.

Photo‐ and thermoinitiated curing of epoxy resins by sulfonium salts

AbstractA number of benzylthiolanium salts have been synthesized, analysed and evaluated by differential scanning calorimetry and viscosity measurements with respect to their potential use as thermal curing agents for epoxy resins. Over a wide range of Hammett constants a correlation exists between initial reactivity, shelf life and the electronic substituent effects of the benzyl group. A combination with arylsulfonium salts leads in singular cases to dual cure systems with attractive properties of thermal and UV induced curing. The sensitization of benzylthiolanium salts also leads to dual cure systems. This opens up new possibilities for UV curable epoxy resins in electronic applications requiring additional curing in shaded areas.

Synthesis of novolac on the basis of bisphenol A as curing agent for epoxy resins

AbstractBisphenol A novolacs were synthesized in a melting process using paraformaldehyde, and in a solution process using a formalin solution and oxalic acid catalyst. 1H‐NMR investigations show a higher content of methylene bridges in the novolacs synthesized in a melting process. These novolacs were analysed by HPLC, GPC, DSC and FT‐IR spectroscopy. The molecular masses were determined by vapour pressure osmometry. The results were shown to be related with the molar ratio of the components. The bisphenol A novolacs were used as curing agents for epoxy resins. There exists a dependence of the gel times on the content of methylene bridges; this dependence is influenced by temperature. The activation energy for gel formation is nearly the same in all curing reactions investigated. The networks synthesized were investigated by thermomechanical analysis.