Investigations on the curing of epoxy resins with hexahydrophthalic anhydride

The bifunctional epoxides bisphenol A diglycidyl ether (BADGE) and hexahydrophthalic diglycidyl ester (HHDGE) as well as the monoepoxides phenyl glycidyl ether (PGE) and cyclohexane carboxylic acid glycidyl ester (CHGE) were cured with hexahydrophthalic anhydride (HHPA) in the presence of benzyldimethylamine (BDMA) or 1-methylimidazole (1-MI) as catalysts at 100–140°C. Investigations of the curing kinetics gave sigmoidal-shaped curves with marked induction periods. IR analysis of the cured products revealed that the propagation proceeds not only by the esterification reaction of epoxide with anhydride but also by chain anhydride formation by the reaction of carboxylate with anhydride groups. ¹³C-NMR investigations of the soluble polymers showed that most of the peaks resulting from double bonds could not be assigned to structures formed by initiation reactions that had previously been proposed for the anhydride curing of epoxides. In analogy to a postulated mechanism for the decarboxylation condensation of HHPA alone in the presence of tertiary amines, it is proposed that an isomerization product of HHPA is one of the molecules that initiate the curing reaction.     

Synthesis of graft polyesters by ring-opening copolymerization of epoxy-terminated poly(ethylene glycol) with acid anhydrides

The copolymerization of epoxy-terminated poly(ethylene glycol methyl ether) (CH₃PEG–epoxide) with phthalic anhydride catalyzed by tertiary amines was performed in o-dichlorobenzene at 100°C to prepare the PEG graft polyester. 4-Dimethylaminopyridine was the most favorable catalyst to give the graft polyester with relatively high molecular weight. The acidity of the reaction solution decreased and M _n of the graft polyesters increased with reaction time. The CH₃PEG/phthalic acid ratio of the products was little affected by the kind of solvent and the reaction temperature above 100°C, but M _n increased with lowering the polarity of solvents and with raising the temperature. Other acid anhydrides, including maleic, succinic, tetrahydrophthalic, and pyromellitic anhydride, could be copolymerized with CH₃PEG–epoxide. The number of branched CH₃PEG chains was controlled by the mixing of low molecular weight epoxide such as n-butyl glycidyl ether. CH₃PEG component of the graft copolymers melted and crystallized at lower temperature than the raw CH₃PEG because of the restriction on the trunk polyester chain.     

Synthesis of graft polyethers by ring-opening copolymerization of epoxy-terminated poly(ethylene glycol) with epoxides

The copolymerization of epoxy-terminated poly(ethylene glycol methyl ether) (CH₃PEG–epoxide) with low molecular weight epoxides such as phenyl ether (PGE) was carried out to prepare the PEG graft polyethers. Potassium tert-butoxide was the most favorable catalyst used to obtain the graft polyethers. The apparent number-average molecular weight (M_n ) of the graft polyethers decreased with increase in PGE concentration because PGE acted as both solvent and comonomer. The composition of the graft polyethers (PGE/CH₃PGE), however, increased with increase in PGE concentration and was almost consistent with the feed ratio of the two monomers. The graft polyethers whose composition was over 10 were insoluble in water. The M_n of the graft polyethers was little affected by the reaction temperature, but more affected by the presence of solvent. Besides PGE, n-butyl glycidyl ether and styrene oxide were effective as comonomers. CH₃PEG–epoxide hardly polymerized in tert-butyl alcohol. © 1994 John Wiley & Sons, Inc.     

Homopolymerization of epoxy monomers initiated by 4‐(dimethylamino)pyridine

The anionic epoxy homopolymerization initiated by tertiary amines, imidazoles, and ammonium salts is a complex reaction exhibiting two undesired characteristics for practical applications: (a) slow reaction rates with long induction periods, and (b) short primary chains due to the high rate of chain transfer reactions. Therefore, these systems have not found an important place in commercial applications. In this study, it is shown that using 4‐(dimethylamino)pyridine (DMAP) as initiator of the polymerization of phenyl glycidyl ether (PGE) or diglycidyl ether of bisphenol A (DGEBA) enables to obtain high polymerization rates and longer primary chains than those generated using typical initiators. A critical molar ratio DMAP/epoxy groups was necessary to attain complete conversion. Networks resulting from the DMAP‐initiated homopolymerization of DGEBA exhibited a high crosslink density and corresponding high values of the glass transition temperature (T_g = 160°C) and of the rubbery elastic modulus (higher than 100 MPa). An intense brown color of reaction products, associated with an absorption band with a maximum at 360 nm, was ascribed to the presence of initiator fragments with conjugated double bonds in chain ends. These results might revalorize the anionic homopolymerization of epoxy monomers for commercial applications. POLYM. ENG. SCI. 46:351–359, 2006. © 2006 Society of Plastics Engineers     

Kinetics of curing reaction of urethane function on base-catalyzed epoxy reaction

The kinetic study on the effect of aromatic-connected carbamate (Ar-carbamate) on the curing reaction of phenyl glycidyl ether (PGE) catalyzed by tertiary amine was carried out through thermal analysis of the reaction by differential scanning calorimetry (DSC). By isothermal DSC analysis, the consumption rate of the epoxide group of PGE was found to be a first-order reaction in the presence of aromatic-connected carbamate in the reaction. It was found that the reaction system has a low activation energy (E_a = 4.63 kcal/mol) as compared to the system without Ar-carbamate (E_a = 6.89 kcal/mol). A reaction mechanism was proposed for this reaction system. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:121–127, 1998     

Influence of backbone rigidity on the curing and the dielectric relaxations of unsaturated polyesters

Unsaturated polyesters with maleic acid and different molar ratio of phthalic anhydride to adipic acid were produced, mixed with styrene, and cured. The degree of double bonds conversion, determined by differential scanning calorimetry (α_DSC), indicating the initial curing, increases significantly with the molar ratio of phthalic anhydride. On the other hand, the degree of double bonds conversion of maleate (α_UP,FTIR) and styrene (α_St,FTIR) units determined by Fourier transform infrared spectroscopy after prolonged curing are considerably higher than α_DSC and increase slightly with the molar ratio of phthalic anhydride. Polyester containing phthalic anhydride without adipic acid (M5P5) has the lowest tetrahydrofuran uptake and diffusion parameter D/α² due to its more rigid segments, in opposite to polyester containing adipic acid (M5A5) having the highest values. According to dielectric spectroscopy measurements, two different relaxations were determined, one beginning above 130°C (with peak above 180°C) attributed to α‐relaxation (dielectric glass transition) and a second one at lower temperatures, attributed to β‐relaxation. The peak of β‐relaxation is at around 130, 75–80, and 30°C for the rigid, intermediate rigidity/flexibility, and flexible polyesters, respectively. The α‐relaxation is determined at low frequencies and the β‐relaxation at intermediate or high frequencies. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of fluorine-containing polyester based on phthalic anhydride and tetrafluoropropyl glycidyl ether

Fluorine-containing polyester (FPE) was synthesized by the reaction of phthalic anhydride, epichlorohydrin, and 2,2,3,3-tetrafluoropropyl glycidyl ether (TFGE) at the catalysis of tetraethylammonium bromide using 1,4-butanediol as the initiator. The structure of FPE was characterized by ¹H NMR and ¹⁹F NMR, and the result showed that the fluorine in TFGE was introduced into FPE. Fluorine content in FPE was determined by oxygen-flask combustion and fluoride selective electrode. It was found that fluorine content in FPEs increased with the increase of TFGE content. The wettability of water and oil on the cured coating based on FPE was investigated by contact angle meter. Contact angles of water and diiodomethane on the cured coatings first increased with the increase of the fluorine content in FPEs and then remained constant. The X-ray photoelectron spectroscopic analysis showed that the F/C molar ratio on the coatings surface was much higher than the overall F/C molar ratio, which indicated that fluoroalkyl groups in FPEs had enriched on the coatings surface. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Epoxy/anhydride networks modified by epoxy/anhydride oligomers containing SiOH groups

Epoxy/anhydride oligomers containing variable amounts of trialkoxysilane groups were synthesized from phenyl glycidyl ether (PGE), 3‐glycidoxypropyl trimethoxysilane (GPMS), and methyl tetrahydrophthalic anhydride (MTHPA), using benzyldimethylamine (BDMA) as an initiator. They were hydrolyzed and partially condensed using diluted formic as a catalyst, with the last step carried out in a solution of diglycidyl ether of bisphenol A (DGEBA). By curing with a stoichiometric amount of MTHPA, in the presence of BDMA, plasticized epoxy/anhydride networks were obtained without any evidence of phase separation. These materials showed a better abrasion resistance than that of the neat matrix. The presence of free SiOH groups can be used to improve the adhesion to glass surfaces. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1365–1370, 2000     

Curing of epoxides with O,O‐di‐t‐butyl phenylphosphonate as thermally latent initiator

The polymerization of glycidyl phenyl ether (GPE) was examined with O,O‐di‐t‐butyl phenylphosphonate (BP) as an initiator in the presence of several Lewis acids, ammonium salts, and methyl cyanoacetate. BP served as an excellent thermally latent initiator in the polymerization of GPE in the presence of ZnCl₂ and Zn(acac)₂. Epikote 828 was cured with BP (5 mol %) in the presence of ZnCl₂ at 150°C to afford the solvent‐insoluble gelled epoxy resin quantitatively, which was thermally more stable than was the one cured without ZnCl₂. No curing took place at room temperature for 7 months. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2347–2351, 2001     

Novel epoxy resins based on cyclohexanone-aldehyde condensation products

Solid ketone-formaldehyde resins are used in certain coating formulations in order to improve hardness, gloss, and light stability. They are soluble, thermoplastic by nature, and contain limited amounts of hydroxyl groups. We found that their primary hydroxyls can be etherified with epichlorohydrin (ECH) either by a two-step ECH-addition/dehydrohalogenation procedure or by a one-step phase-transfer process. An intermediate of particular usefulness is the crystalline 2,2,6,6-tetramethylol-cyclohexanol (TMCH) made from cyclohexanone and 5 mol formaldehyde, yielding low colored epoxy resins with epoxy values up to 7.5 eq/kg. Depending upon the nature of the curing agent, high T_g solids as well as tough and flexible coatings with good outdoor stability can be made. Upon decreasing the formaldehyde–cyclohexanone ratio, solid condensation polymers melting up to 150°C can be obtained. Phase-transfer glycidylation yielded solid thermoset glycidyl ether resins with M?_n up to 1600, M?_ω up to 13,000, epoxy values up to 3.6 eq/kg, and softening points between 80 and 160°C. Powder coatings formulated with carboxyterminated polyesters are hard, glossy, solvent-resistant but somewhat brittle. In order to overcome this drawback, polycycloacetals have been produced from TMCH and glutardialdehyde, which are terminated by pairs of methylol groups. Powder coatings of the corresponding glycidylethers with carboxyl-terminated polyesters exhibited excellent flexibility and impact strength.     

Preparation and fluorine enrichment behavior of fluorinated polyester

Poly[1,2-propylene glycol-3-(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptoxy)]phthalate (PDFP) was prepared by the reaction of phthalic anhydride, epichlorohydrin, and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl glycidyl ether (DFGE). The structure of PDFP was characterized with ¹H-NMR, ¹⁹F-NMR, FTIR and the wettability of water and oil on cured PDFP coatings was investigated by contact angle meter. The results showed that the contact angle of water and diiodomethane on cured coatings increased with the increase of the fluorine content and could maximally attain 108° and 69°, respectively. At a fluorine content of 0.75%, the surface energy was 21.1 mJ/m². X-ray photoelectron spectroscopic (XPS) analysis showed that the surface F/C atomic ratio was much higher than the overall F/C molar ratio, indicating that the fluoroalkyl groups in PDFP had enriched on the coating surface. It was also found that the fluorinated polyester with longer fluoroalkyl groups had the higher tendency to enrich on the coating surface.     

An UV‐curable epoxy acrylate oligomer with high refractive index containing fluorene: Preparation,characterization, and application

In this article, a novel UV‐curable epoxy acrylate oligomer (BPEFPGMA) with high refractive index is successfully prepared through semi‐esterification reaction of 9,9‐bis[4‐(2‐hydroxyethoxy)phenyl]fluorene and phthalic anhydride, followed by end‐caping of glycidyl methacrylate. After 15 times’ repetitions, the process and properties of this oligomer are stable and reliable. The resulting BPEFPGMA exhibited low solvent content (≤1600 ppm), low viscosity (1900–2500 mPa s at 60°C), high refractive index (1.587 ± 0.003 at 20°C), and normal M_w (2550–3536 g/mol). The coating formulations of 1.57 UV‐curable glue are mixed with BPEFPGMA as reactive oligomer. Through the technology of UV‐curing forming, the corresponding brightness enhancement films are obtained. The resulting films exhibit normal structure, excellent adhesion (5B), good scratch resistance (50 g), and good abrasion resistance (50 g). They show excellent performance, and have reached the quality standard for use in liquid crystal display industry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42386.     

Cationic polymerization behavior of β‐methylglycidyl ether derivatives and physical properties of their cationically cured materials

β‐Methylglycidyl ethers have been applied to Electrical and Electronic adhesives. However, there is no report about the detailed polymerization behavior and physical properties of their cured products. Hence, we investigated cationic polymerization behavior of bisphenol A di(β‐methylglycidyl) ether (Me‐BADGE) and physical properties of the cured products containing Me‐BADGE. DSC analysis suggested that Me‐BADGE could be cured completely at lower temperature than bisphenol A diglycidyl ether (BADGE). Physical properties were analyzed by dynamic viscoelastic analysis. Glass transition temperature (T_g) of BADGE homopolymer was 194°C. In contrast, the copolymer of BADGE (50 wt %) with Me‐BADGE (50 wt %) showed T_g at 124°C. According to the data of E’ and tan δ, crosslink density of the cured products decreased with increasing the Me‐BADGE content. The analysis of cationic polymerization of monofunctional β‐methylglycidyl ether suggested that the cationic polymerization proceeded not only through oxonium cation but also through carbocation formed by ring‐opening reaction of oxonium cation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42377.     

Copolymerization of glycidol with functionalized phenyl glycidyl ethers

Various copolymers of glycidol with phenyl‐containing comonomers (glycidyl 2‐methylphenyl ether, 2‐biphenylyl glycidyl ether, 4‐tert‐butylphenyl glycidyl ether, methoxyphenyl glycidyl ether, and p‐nitrophenyl glycidyl ether) were synthesized by cationic ring‐opening polymerization, for possible use as nanoparticle coatings. The copolymerization involving p‐nitrophenyl glycidyl ether produced p‐nitrophenol as a byproduct. The copolymers were found to have relatively low average molecular weights and high polydispersities, with glass‐transition temperatures in the ?20 to +10°C range (approximately). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1462–1466, 2005     

Toughening of epoxy resins by modification with aromatic polyesters

Aromatic polyesters, prepared by the reaction of phthalic or isophthalic acids and α,ω-alkanediols, were used to reduce the brittleness of bisphenol-A diglycidyl ether epoxy resin cured with methyl hexahydrophthalic anhydride. These polyesters were effective as modifiers for toughening of the epoxy resin system. The most suitable composition for modification of the epoxy resins was inclusion of 20 wt % of poly(ethylene phthalate) (MW 7200), which resulted in a 150% increase in the fracture toughness (K_IC) of the cured resin at no expense of its mechanical properties. The effectiveness of poly(alkylene phthalate)s as modifiers decreased with increasing the chain length of alkylene units. The toughening mechanism was discussed based on the morphological and dynamic mechanical behaviors of the modified epoxy resin system.     

Enzyme‐catalyzed copolymerization of oxiranes with dicarboxylic acid anhydrides

Ring‐opening copolymerizations of the oxiranes glycidyl phenyl ether (GPE) and diglycidyl ether of bisphenol A (DGEBA) with a dicarboxylic acid anhydride [methyl hexahydrophthalic anhydride, nadic anhydride, maleic anhydride (MA), or itaconic anhydride (IA)] were carried out with the lipases Candida cylindracea (CCL), Lipozyme TL‐IM (LIM), and Novozyme 435 (N435) as catalysts. The CCL‐catalyzed reaction of DGEBA with MA or IA (at a 1:2 molar ratio) at 80°C resulted in only partial curing. We monitored the reactions by Fourier transform infrared spectroscopy and by following the changes in the intensities of carbonyl stretching frequencies of the anhydride and ester groups. The reactivity of the oxirane group in GPE was higher than that in DGEBA; this may have been due to the higher viscosity of DGEBA. The reactivities of the enzymes for the copolymerization of the oxiranes and dicarboxylic acid anhydride were in the order LIM > CCL > N435. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 697–704, 2005     

Curing of epoxide resins by anhydrides of dicarboxylic acids: model reactions

Summary The kinetics of the polyaddition reaction of epoxy resins were studied using the model system phenyl glycidyl ether, phthalic anhydride, tertiary amine. N,N-dimethyl-benzylamine and N,N-dimethylaniline were used as tertiary amines. Furthermore the influence of phenol and benzoic acid was investigated. The oligomer products were separated by high pressure liquid chromatography. A reaction scheme of the copolyaddition and the structure of the products were proposed.     

Synthesis,characterization, and gas transport properties of new semifluorinated poly(ether imide)s containing cardo moiety

A series of new semifluorinated poly(ether imide)s (PEI)s was synthesized from a diamine monomer, 9,9‐bis ‐[3‐phenyl‐4‐{2′‐trifluoromethyl‐4′‐(4′′‐aminophenyl)phenoxy} phenyl]fluorene on reaction with three different aromatic dianhydrides namely, 4,4′‐(4,4′‐isopropylidenediphenoxy)bis (phthalic anhydride), 4,4'‐(hexafluoro‐isopropylidene)diphthalic anhydride, and 4,4'‐oxydiphthalic anhydride. The PEIs were well characterized by elemental analysis, spectroscopic, thermal, mechanical, electrical, and optical techniques. The synthesized PEIs showed high glass transition temperature (T_g up to 288 °C) and high thermal stability (T_{d ,10} up to 521 °C under synthetic air), high tensile strength, up to 76 MPa and low dielectric constant (?) (2.35–2.61 at 1 MHz). The membranes prepared from these polymers were studied for their gas permeability for four different gases CO₂, O₂, N₂, and CH₄. The PEI membranes showed high gas permeability (P _CO2 up to 70.3 and P _O2 up to 16.7 Barrer) and high permselectivity (P _CO2/P _CH4 up to 73.6 and P _O2/P _N2 up to 13.4); for the O₂/N₂ gas pair the PEIs surpassed the present upper boundary limit of 2008 drawn by Robeson. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45213.     

Crown ethers as new curing agents for epoxy resins

Different crown ethers (4‐aminobenzo‐15‐crown‐5 (4‐aminobenzo‐15‐C5), 1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (diaza‐18‐crown‐6), tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (H₄DOTA) and tetraazacyclododecane‐1,4,7,10‐tetraacetamide (H₂ODDA)) were used as curing agent for bisphenol A diglycidyl ether (BADGE, n = 0). The maximum enthalpy change for all systems except that formed by the epoxy resin with H₄DOTA corresponds to a stoichiometric ratio, since from this value the reaction enthalpies decrease when the proportion of epoxy increases. Heteropolymerization reaction occurs in all the crown ethers. Etherification reactions occur at temperatures much lower (30 °C less) than for the porphyrin systems studied in which a second signal appears at 300 °C. The etherification is evidenced by a slight shoulder in the thermograms for H₄DOTA and H₂ODDA. The systems BADGE (n = 0)/4‐aminobenzo‐15‐C5 and BADGE (n = 0)/diaza‐18‐crown‐6 improve the thermal stability of the epoxy resin by 30 °C approximately while the improvement for BADGE (n = 0)/H₄DOTA and BADGE (n = 0)/H₂ODDA is about 60 °C. © 2017 Society of Chemical Industry     

1-氯-3-苯氧基-2-丙醇的合成

以环氧氯丙烷和苯酚为原料,在无水碳酸钾存在下缩合得到缩水甘油苯基醚,再与盐酸反应得到1-氯-3-苯氧基-2-丙醇,总收率71．4％(以苯酚计)。目标化合物结构通过红外光谱、核磁共振氢谱及碳谱得以证实。