环氧防水涂料固化剂酮亚胺合成方法及性能

环氧树脂防水涂料的性能与固化剂有着很大的关系.本文作者合成出一种酮亚胺固化剂,通过实验考察了影响其产率的因素,并与其他三种常用的固化剂在性能上进行了比较.结果表明,酮亚胺的固化效果优良,当甲基异丁基酮(MIBK)与间苯二甲胺(MXDA)单体投料比为3∶1时,产率较高,最佳的合成反应温度为130℃,反应时间为3.5h.     

Effect of new nonionic curing agent on curing kinetics and mechanical properties of epoxy resin

The current research work presents a novel nonionic curing agent (AEDA) synthesized by utilizing ethylene glycol diglycidyl ether (EGDE), 3,4-dimethoxyaniline (DI), and triethylenetetramine (TETA). Infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to characterize the structure of AEDA curing agent. Non-isothermal scanning calorimetry was used to determine the activation energy and curing conditions of epoxy resin in the curing process. An impact testing machine, a tensile testing machine and a scanning electron microscope (SEM) were used to analyze the impact strength, tensile strength, bending strength, and micromorphology of the AEDA/E-51 system with different mass ratios. The results show that AEDA is an effective high-temperature curing agent. For the AEDA/E-51 system with the optimal mass ratio of 10:100, the best curing temperature is 92.15°C, and the post-curing temperature is 135.65°C. Furthermore, the apparent activation energy (E_a) of 1670 J/mol, the pre-exponential factor (A) of 3.7 × 10^?4, and the reaction series (n) value of 0.76 are obtained for the AEDA/E-51 system. The impact strength of AEDA/E-51 epoxy resin polymer is 7.82 kJ/m², tensile strength is 14.2 MPa, and bending strength is 18.92 MPa. The micromorphological results of the AEDA/E-51 system are consistent with the results of DSC test and mechanical properties test. Hence, this study provides theoretical support for the practical applications of AEDA as curing agent.     

Preparation of phosphorus‐containing phenolic resin and its application in epoxy resin as a curing agent and flame retardant

For the sake of improving the flame retardancy of epoxy resin (EP), a novel phosphorus‐containing phenolic resin (PPR) synthesized in our group instead of conventional phenolic resin (PR) was used to cure EP in the present research. The curing processes and the corresponding crosslinking structure and mechanical performance were investigated by differential scanning calorimeter and dynamic mechanical thermal analysis. Because of the introduction of flame‐retarding elements including P and Si, PPR exhibited higher charring capacity in the condensed phase, which is helpful to construct a char layer of higher quality. Correspondingly, PPR‐cured EP displayed remarkably improved flame retardance as compared to conventional PR‐cured EP through the related evaluations including limiting oxygen index, vertical burning test, and microscale combustion colorimeter. As a multifunction agent, it is believable that PPR possesses potential commercial value to prepare flame‐retardant EP with high performance.     

Curing kinetics and thermal stability of epoxy blends containing phosphorous-oxirane with aromatic amide-amine as curing agents

This article describes the synthesis of a series of aromatic amide-amines and their potential use as epoxy hardeners. These amines were synthesized by the reaction of L-phenylalanine（PA） with diamines of different structures i.e.1,4- phenylene diamine（PD）,1,5-diamino naphthalene（N）,4,4’-（9-fluorenyllidene）-dianiline（F）,4,4’-diaminodiphenyl sulphide （DS） and 3,4’-oxydianiline（O） in a stoichiometric ratio（1:1）.Structural characterization of synthesized amide-amines was done with the help of elemental analysis and spectroscopic techniques viz.FT-IR,¹H-NMR and ¹³C-NMR.An epoxy blend was prepared by mixing tris（glycidyloxy） phosphine oxide（TGPO） with conventional epoxy i.e.diglycidyl ether of bisphenol-A（DGEBA） in an equivalent ratio of 2:3 to incorporate phosphorous into the main chain.The curing kinetics of the epoxy blend with synthesized aromatic amide-amines was investigated by non-isothermal DSC technique using multiple heating rate method（5,10,15 and 20 K/min.）.The activation energies were determined by fitting the experimental data into Kissinger and Ozawa kinetic models.The activation energies obtained through Ozawa method were slightly higher than those of Kissinger method but were comparable.However,both the energies were found to be dependent on the structure of amines.The thermal stability and weight loss behavior of isothermally cured thermosets were also investigated using thermogravimetric analysis（TGA） in nitrogen atmosphere.All the samples showed improved thermal stability in terms of char yield than using only amines as hardeners.     

Synthesis and characterization of epoxy resins containing imine group and their curing processes with aromatic diamine

The epoxy resins containing imine bonding were prepared from hydroxyl substituted Schiff base monomers in two steps. At the first step, hydroxyl substituted Schiff base monomers were synthesized via condensation reaction. At the second step, epoxy resins were synthesized from the reaction between Schiff base monomers and epichlorohydrine (EPC). Then curing processes of epoxy resins were achieved by p-phenylenediamine compound. The structures of resulting compounds were confirmed by FT-IR, UV-Vis and ¹H-NMR. TG-DTA and DSC measurements were performed for thermal characterizations of the compounds. Chemical resistances of the cured epoxy-amine systems were determined for coating applications in acidic, alkaline and organic solvents. HCl (10%, aqueous solution), NaOH (10%, aqueous solution), DMSO, DMF, N-methylpyrrolidone, ethanol, THF and acetone were used for corrosion tests. Chemical resistance data of the synthesized epoxy resins demonstrated that they have good chemical resistance against various acid, alkaline and common organic solvents. Surface morphologies of epoxy resin and the cured epoxy resin were determined with scanning electron microscopy (SEM) measurements. Also, optical band gap (E_g) values of Schiff base monomers and epoxy resins were calculated from UV-Vis measurements.     

Synthesis and photopolymerization kinetics of multifunctional aromatic urethane acrylates containing tertiary amine group

Two multifunctional aromatic urethane acrylates, based on 2, 4‐toluene diisocyanate (2, 4‐TDI), β‐hydroxyethyl arcylate (HEA), and synthetic multifunctional hydroxyl compounds, were synthesized by classical condensation reaction. FTIR was used to monitor the process of the reaction. The photopolymerization kinetics of the urethane acrylates with different photoinitiators was studied by Real‐Time Infrared Spectroscopy. The results indicated that different from the commercial urethane acrylate CN 975, the synthetic multifunctional urethane acrylates could be efficiently initiated by BP without the addition of any co‐initiators as they have tertiary amine structures. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of rigid polymer containing pendant norbornadiene moieties and its photochemical valence isomerization

Polymers having pendant norbornadiene (NBD) moieties and rigid main chain were prepared from the reaction of partially brominated poly(2,6-dimethyl-p-phenylene oxide) with a potassium carboxylate derivative of the corresponding NBD using a phase transfer catalyst in chlorobenzene. The photochemical valence isomerization of pendant NBD to quadricyclane (QC) moieties proceeded smoothly in the film state as well as polymer solution upon the irradiation by sunlight, xenon lamp, or high-pressure mercury lamp. The rate of isomerization was affected by the structure of main chain in the polymer and the substituent groups of NBD derivatives. The catalytic reversion of the resulting QC moiety to the original NBD proceeded smoothly in the solution with (5,10,15,20-tetraphenyl-21H,23H-por-phine)cobalt(II) as the catalyst at room temperature; however, the reaction of NBD polymer containing poly(2,6-dimethyl-p-phenylene oxide) (PPO) showed lower reactivity than that of the corresponding low molecular weight QC compound. When the cycle between the photochemical valence isomerization of NBD moiety to quadricyclane (QC) moiety and thermal reversion of QC moiety to NBD moiety at 160°C was repeated, the NBD polymer synthesized from PPO degraded gradually, whereas NBD polymer prepared from poly(4-chloromethylstyrene) decomposed easily. Therefore, the rigid PPO structure showed high resistance for the degradation of NBD moiety. © 1994 John Wiley & Sons, Inc.     

Curing behavior and kinetics of epoxy resins cured with liquid crystalline curing agent

This article describes the synthesis of a liquid crystalline curing agent 4,4′-bis-(4-amine-butyloxy)-biphenyl (BABB), and its application as a curing agent for the epoxy resin (DGEBA) in comparison with normal curing agent, 4,4′-diaminobiphenyl (DABP). BABB was investigated with polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scatting, and the results showed that BABB displayed smectic liquid crystalline phase. The curing behaviors of DGEBA cured with BABB and DABP were studied by using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and dynamic mechanical analysis (DMA). The results indicated that BABB showed a higher chemical reactivity than DABP. The kinetics was studied under isothermal conditions using an isoconversional method, and the isothermal DSC data can be fitted reasonably by an autocatalytic curing model. The nematic droplet texture was observed for the resulting polymer network of DGEBA/BABB system, while the DGEBA/DABP system showed an isotropic state. The storage modulus of DGEBA/BABB system was enhanced in comparison with DGEBA/DABP system because of the formation of LC phase, whereas the glass transition temperatures decreased because of the introduction of flexible spacer group.     

Synthesis and curing kinetics of cardanol‐based curing agents for epoxy resin by in situ depolymerization of paraformaldehyde

Three novel cardanol‐based phenalkamines with good stability have been successfully prepared by Mannich reaction using phenolic compounds with paraformaldehyde and hexamethylenediamine (or its mixture with other amines). The structure of the prepared phenalkamines has been analyzed using liquid chromatography‐mass spectrometry, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The curing kinetics of the prepared epoxy resin/phenalkamine systems has been investigated using differential scanning calorimetry (DSC), and determined by Kissinger, Flynn–Wall–Ozawa, and Crane methods. Furthermore, the thermal properties of the cured materials have been evaluated using DSC and thermogravimetric analysis, and the mechanical properties of the cured materials have been analyzed systematically. The results demonstrate that the phenalkamine 1 (PAA1) had a lower reactivity and better toughness than phenalkamine 2 (PAA2) and phenalkamine 3 (PAA3). In addition, PAA1 is a solid curing agent, while PAA2 and PAA3 are liquid curing agents, which were more convenient for practical usage. Results indicate that the properties of the prepared phenalkamines strongly depend on the structures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 472–480     

Effects of reactive diluent diepoxidized cardanol and epoxy fortifier on curing kinetics of epoxy resin

Different formulations, composed of the diglycidyl ether of bisphenol-A, diepoxidized cardanol as reactive diluent, an anhydride as curing agent, and a tertiary amine as curing catalyst, with/without the use of an epoxy fortifier, were analysed. The effect of the fortifier on the diluent was also observed. The overall kinetics of curing was observed to follow a simple Arrhenius-type temperaturedependence, with an activation energy in the range 54–120 kJ/mol, with first-order kinetics up to 85% conversion. An increase in activation energy was observed with an increase of diluent content. The curing reaction was found to follow a three-step mechanism, involving a nucleophilic bimolecular displacement reaction, for which an explanation was offered. Incorporation of the fortifier lowers the curing temperature, but does not alter the final degree of reaction.

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Zusammenfassung Es wurden verschiedene Ausgangsgemische, bestehend aus dem Diglyzidyläther von Bisphenol A, diepoxydiertem Kardanol als reaktives Streckmittel, einem Anhydrid als Vernetzungsmittel und einem tertiären Amin als Vernetzungskatalysator mit bzw. ohne Anwendung eines Fortifyers untersucht. Der Einfluss des Fortifyers auf das Streckmittel wurde ebenfalls untersucht. Die Bruttokinetik der Vernetzung zeigt eine Temperaturabhängigkeit einfachen Arrhenius-Types mit einer Aktivierungsenergie im Bereich von 54–120 kJ/mol sowie einen Reaktionstyp erster Ordnung mit einer Konversionsrate von 85%. Ein steigender Streckmittelgehalt bewirkt ein Anwachsen der Aktivierungsenergie. Der Vernetzungsreaktion liegt ein Dreistufenmechanismus zu Grunde, der unter anderem auch eine nukleofile bimolekulare Substitutionsreaktion beinhaltet. Der Einsatz eines Fortifyers senkt zwar die Vernetzungstemperatur, verändert aber nicht die Endkonversionsrate.

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Study on curing reaction of epoxy resin modified with prepolymers containing spiro orthocarbonate

Prepolymers were prepared by the reaction of 3,9-dihydroxyethyl-3′9′-dibenzyl-1,5,7,11-tetraoxaspiro(5,5)undecane with 4,4′-diphenylmethane diisocyanate (MDI) and 1,6-hexa-methylene diisocyanate (HDI). The number-average molecular weights of the prepolymers can be controlled by changing the mole ratios of spiro compound and diisocyanates. Kinetic studies of the cure reaction for the epoxy resin system modified with or without prepolymers were followed by a HLX-1 dynamic torsional vibration apparatus. The results indicated that gel time (t_g) and activation energy (E_a) increased as the content of prepolymers in the epoxy resin system increased. A difference with the cure reaction of the pure epoxy resin, the second-order reaction for the epoxy resin modified with the prepolymers, was obtained. Rate constants (k) of the cure reaction are 0.231 min^?1 for the epoxy resin, and 0.312 min^?1 for the modified epoxy resin. The mechanism of the cure reaction was discussed. © 1995 John Wiley & Sons, Inc.     

A novel halogen‐free co‐curing agent with linear multi‐aromatic rigid structure as flame‐retardant modifier in epoxy resin

A novel halogen‐free 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐containing co‐curing agent, 6,6′‐(1,4‐phenylenebis(((4‐(phenylamino)phenyl)amino)methylene))bis(dibenzo[c,e][1,2]oxaphosphinine 6‐oxide) (DPN) was synthesized via a simple 1‐pot or 2‐step procedure with yield of 86.2% and 70.8%, respectively. The molecular structures of 4,4′‐((1,4‐phenylenebis(methanylylidene))bis(azanylylidene))bis(N‐phenylaniline) (DPN intermediate) and DPN are characterized by FTIR, NMR, and MS. TGA tests show that the char yield of DPN/EP composites raises to 30.9% when the molar ratio of DPN to 4,4‐diaminodiphenyl methane(DDM) is 20:80. T_g values of DPN/EP composites tested by DSC and DMA are similar to neat epoxy resin (EP), which is due to the secondary amine in DPN that participates in the cross‐linking reaction of epoxy resin. The storage modulus in the rubber stage (E′‐190 °C) of flame‐retardant epoxy resin is close to that of neat EP, while their tanδ's are lower, which indicates the similarity of samples' cross‐linking density due to the participation of DPN in the cross‐linking reaction. The results show that when the molar ratio of DPN and DDM is 5:95, the epoxy has a higher T_g value and better mechanical properties than other samples. The introduction of DPN efficiently improves the flame‐retardant properties of epoxy resin with V‐0 rating of UL‐94 vertical burning test, non‐dripping, 41% of limit oxygen index (LOI) value, low peak heat release rate (PHRR), and total heat release (THR).     

Reaction pathway of liquid crystalline epoxy resin/aromatic diamine curing system

The reaction pathway of a monotropic liquid crystalline epoxy resin (HQEP2) was studied using FT‐IR and DSC. The reaction mechanism was correlated with the amine to epoxy ratio, curing temperature and morphology of the curing system. Experimental results showed that the linearly growing molecules lead to a nematogen but branching intermediates induced an isotropic texture.     

Synthesis and curing behavior of a novel liquid crystalline epoxy resin

This article described the synthesis and mesomorphic behavior transition of a novel liquid crystalline (LC) epoxy resin 4-(2,3-epoxypropoxy)biphenyl,4″-(2,3-epoxypropoxy)phenyl-4′carboxylate (EBEPC), which combined a hydroxyl benzoic aromatic ester and biphenol rigid-rod group. EBEPC showed a clear nematic schlieren texture under curtain conditions. The reaction kinetics of EBEPC cured by 4,4′-diaminodiphenyl-methane (DDM) was studied by using an isoconversional method under isothermal conditions with differential scanning calorimetry (DSC). The isothermal DSC data can be fitted reasonably by an autocatalytic curing model. Smectic phases had been observed in the EBEPC/DDM curing system. The results of DSC showed that the formation of the LC phase had pronounced influence on the curing reaction.     

水性环氧树脂的研制及其固化性能研究

采用端甲氧基聚乙二醇、马来酸酐、E-44环氧树脂合成了反应型环氧树脂乳化剂MeO-PEG-Ma-E-44,以相反转乳化技术制备E-44水性环氧树脂,研究了工艺条件对其性能的影响。结果表明:酯化率达98.5%的MeO-PEG-Ma-E-44,用量为E-44的ω=16.5%-20%得到的水性环氧树脂乳液最稳定。DSC和TG分析结果表明:乳化前后的E-44环氧树脂都能室温条件2h内很好的固化,固化后热性能基本不变,分解温度约在380℃,热失重率89%,其玻璃转变温度有所降低,韧性有所提高,其它性能基本不受影响。     

Effect of curing agent and temperature on the rheological behavior of epoxy resin systems

The effect of curing agent (6610) content and temperature on the rheological behavior of the epoxy resin CYD-128 was studied by DSC analysis and viscosity experiments. The results show that the resin system meets the requirements of processing technology. A complete reaction occurs when the curing agent content (40 parts per hundred resin, phr) is a little higher than the theoretical value (33.33 phr), while the degree of reaction of the resin system is reduced when the curing agent content is lower (25.00 phr) than theoretical value. However, excessive curing agent (50.00 phr) results in a lower reaction rate. Curing agent content has little influence on gel time when curing agent content exceeded 33.33 phr and the temperature was less than 70 °C. The isothermal viscosity-time curves shift towards the -x axis when the temperature rises from 50 °C to 80 °C. Meanwhile, higher temperature results in higher reaction rates.     

Flame‐retardant epoxy resin compounds containing novolac derivatives with aromatic compounds

New flame‐retardant epoxy resin compounds containing novolac derivatives with specific aromatic compounds have been developed. After crosslinking reactions between epoxy resin and hardener, the epoxy resin compounds formed highly flame‐retardant network structures that were obtained by including biphenylene and phenylene moieties in the main chains of novolac‐type epoxy resin and phenol novolac resin hardener. The high flame retardancy is due mainly to the stable foam layers that form during combustion because of the low elasticity at high temperatures and the high pyrolysis resistance of the compounds. Furthermore, the addition of excess phenol derivative hardener not only facilitates the formation of the foam layers by decreasing the crosslink densities but also reduces the amount of flammable substances generated from the epoxy resin compounds during combustion. The use of a multifunctional epoxy resin containing four glycidyloxy groups in the compounds improved characteristics such as heat resistance and strength at high temperatures, while maintaining excellent flame retardancy. Copyright © 2001 John Wiley & Sons, Ltd.     

Aspects of epoxy resin curing reactions

The progress that has been made in establishing the mechanism of the curing reaction between epoxides and amines, particularly through the use of calorimetric methods (DSC), is discussed. A novel application of tritium-labelled compounds to the study of the reaction of epoxides with imidazoles is also presented. The radiochemical method has produced an enhanced understanding of the reaction mechanism and has given kinetic data in good agreement with DSC measurements.