New type of phenolic resin—The curing reaction of bisphenol A based benzoxazine with bisoxazoline and the properties of the cured resin. III. The cure reactivity of benzoxazine with a latent curing agent

The curing reaction of a bisphenol A based benzoxazine [2,2‐bis(3,4‐dihydro‐3‐phenyl‐1,3‐benzoxazine) propane (Ba)] and bisoxazoline with a latent curing agent and the properties of the cured resins were investigated. With a latent curing agent, the ring‐opening reaction of the benzoxazine ring occurred more rapidly, and then the phenolic hydroxyl group generated by the ring‐opening reaction of the benzoxazine ring also reacted with the oxazoline ring more rapidly. The cure time of molten resins from Ba and bisoxazoline with a latent curing agent was reduced, and the cure temperature was lowered, in comparison with those of resins from Ba and bisoxazoline without a latent curing agent. The melt viscosity of molten resins from Ba and bisoxazoline with a latent curing agent was kept around 50 Pa s at 80°C even after 30 min, and molten resins from Ba and bisoxazoline with a latent curing agent showed good thermal stability below 80°C. However, above 170°C, the curing reaction of Ba with bisoxazoline with a latent curing agent proceeded rapidly. Cured resins from Ba and bisoxazoline with a latent curing agent showed good heat resistance, flame resistance, mechanical properties, and electrical insulation in comparison with cured resins from Ba and bisoxazoline without a latent curing agent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Glass fiber‐reinforced composite based on benzoxazine resin

In this study, we aimed to prepare and characterize glass fiber‐reinforced composites (GFRP) based on benzoxazine resins. Therefore, the molten resin from benzoxazine and bisoxazoline with the latent curing agent was used as the matrix resin, and the properties of GFRP based on the molten resins were investigated. The properties of GFRP were estimated by mechanical properties, heat resistance, and flame resistance. As a result, it was found that GFRP based on the molten resins from benzoxazine and bisoxazoline with the latent curing agent showed good heat resistance, flame resistance, and mechanical properties compared with those of the conventional GFRP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

New thermosetting resin from poly(p‐vinylphenol) based benzoxazine and epoxy resin

Poly(p‐vinylphenol) (VP) based benzoxazine was prepared from VP, formaline, and aniline. The curing behavior of the benzoxazine with the epoxy resin and the properties of the cured resin were investigated. Consequently, the curing reaction did not proceed at low temperatures, but it proceeded rapidly at higher temperatures without a curing accelerator. The reaction induction time or cure time of the molten mixture from VP based benzoxazine and epoxy resin was found to decrease, compared with those from conventional bisphenol A based benzoxazine and epoxy resin. The curing reaction rate of VP based benzoxazine and epoxy resin increased more than that of conventional bisphenol A based benzoxazine and epoxy resin. The properties of the cured resin from neat resins and from reinforced resins with fused silica were evaluated. The cured resins from VP based benzoxazine and epoxy resin showed good heat resistance, mechanical properties, electrical insulation, and water resistance compared to the cured resin from VP and epoxy resin using imidazole as the catalyst. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 555–565, 2001     

Studies on new type of phenolic resin (IX) curing reaction of bisphenol A‐based benzoxazine with bisoxazoline and the properties of the cured resin. II. Cure reactivity of benzoxazine

Bisphenol A‐based benzoxazine that contained oligomers (oligo‐Ba) was prepared from bisphenol A, formaline, and aniline. Curing reaction of oligo‐Ba with bisoxazoline and the properties of the cured resin were investigated. Consequently, the ring‐opening reaction of benzoxazine ring occurred, and then the phenolic hydoroxyl group generated by the ring‐opening reaction of benzoxazine ring reacted with oxazoline ring. It was found that the cure induction time and cure time of the molten mixture from oligo‐Ba and bisoxazoline could be reduced and also the cure temperature could be lowered, compared with those from bisphenol A‐based benzoxazine, which contained no oligomers (Ba), and bisoxazoline. The melt viscosity of the molten mixture from oligo‐Ba and bisoxazoline was kept 0.1–10 [Pas] at 140°C even after 40 min, the molten mixture from oligo‐Ba and bisoxazoline showed good flowability below 140°C as well as that from Ba and bisoxazoline. However, above 160°C the curing reaction of oligo‐Ba with bisoxazoline proceeded more rapidly than that of Ba with bisoxazoline. The cured resin from oligo‐Ba and bisoxazoline showed good heat resistance and water resistance, compared with the cured resin from Ba and bisoxazoline. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2331–2339, 2001     

New thermosetting resin from terpenediphenol‐based benzoxazine and epoxy resin

Terpenediphenol‐based benzoxazine was prepared from terpenediphenol, formaline, and aniline. Curing behavior of the benzoxazine with epoxy resin and the properties of the cured resin were investigated. Consequently, the curing reaction did not proceed at low temperatures, but it proceeded rapidly at higher temperatures without a curing accelerator. The properties of the cured resin both from neat resins and from reinforced resins with fused silica were evaluated, respectively. The cured resins showed good heat resistance, mechanical properties, electrical insulation, and especially water resistance, compared with the cured resin from bisphenol A type novolac and epoxy resin. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2266–2273, 1999     

New thermosetting resin from bisphenol A‐based benzoxazine and bisoxazoline

Bisphenol A‐based benzoxazine was prepared from bisphenol A, formaline, and aniline. Curing reaction of bisphenol A‐based benzoxazine with bisoxazoline and the properties of the cured resin were investigated. Consequently, using triphenylphosphite as a catalyst, for the first time the ring‐opening reaction of benzoxazine ring occurred at 170°C, and then the phenolic hydroxyl group generated by the ring‐opening reaction of the benzoxazine ring reacted with the oxazoline ring at 200°C. The melt viscosity of the molding compound was kept 0.1–1 Pa · s at 140°C even after 1.5 h, and increased rapidly at 180°C. It was realized that the molding compound showed good flowability below 140°C, curing reaction proceeded above 180°C rapidly. The cured resin from bisphenol A‐based benzoxazine and bisoxazoline showed good heat resistance, water resistance, electrical insulation, and mechanical properties, compared with the cured resin from bisphenol A‐type novolac and bisoxazoline. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1551–1558, 1999     

Epoxy resin cured by bisphenol A based benzoxazine

Bisphenol A based benzoxazine was prepared from bisphenol A, formaline, and aniline. This benzoxazine was used as a hardener of the epoxy resin. Curing behavior of the epoxy resin and the properties of the cured resin were investigated. Consequently, curing reaction proceeded without a curing accelerator. The molding compound showed good thermal stability under 150°C, which corresponded to the temperature in the cylinder of injection molding. Above 150°C, the curing reaction proceeded rapidly. The cured epoxy resin showed good heat resistance, water resistance, electrical insulation, and mechanical properties compared with the epoxy resin cured by the bisphenol A type novolac. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1903–1910, 1998     

Synthesis and characterization of diphenylsilanediol modified epoxy resin and curing agent

A series of diphenylsilanediol modified epoxy resins and novel curing agents were synthesized. The modified epoxy resins were cured with regular curing agent diethylenetriamine (DETA); the curing agents were applied to cure unmodified diglycidyl ether of bisphenol A epoxy resin (DGEBA). The heat resistance, mechanical property, and toughness of all the curing products were investigated. The results showed that the application of modified resin and newly synthesized curing agents leads to curing products with lower thermal decomposition rate and only slightly decreased glass transition temperature (T_g), as well as improved tensile modulus and tensile strength. In particular, products cured with newly synthesized curing agents showed higher corresponding temperature to the maximum thermal decomposition rate, comparing with products of DGEBA cured by DETA. Scanning electron microscopy micro images proved that a ductile fracture happened on the cross sections of curing products obtained from modified epoxy resins and newly synthesized curing agents, indicating an effective toughening effect of silicon–oxygen bond.     

Novel phosphorilated flame retardant thermosets: epoxy-benzoxazine-novolac systems

Modified novolac resins with benzoxazine rings were prepared and cured with isobutyl bis(glycidylpropylether) phosphine oxide (IHPOGly) as crosslinking agent. Their curing behaviour using different epoxy/phenol molar ratios and with or without triphenylphosphine as catalyst was studied. Two different phenolic groups react with oxirane ring, those initially free and those generated after benzoxazine ring opening. In absence of catalyst, it is not possible to distinguish between them. However, for the catalyzed curing of the highest modification degree benzoxazine based novolac resin is possible to distinguish both reactions. The thermal, thermomechanical and flame retardant properties of the cured materials were measured. V-O materials were obtained when the resins were tested for ignition resistance with the UL-94 test.     

Characteristics of epoxy resin cured with in situ polymerized curing agent

In order to improve the heat resistance of a cured epoxy resin together with reducing the viscosity of the resin composition, an epoxy resin was cured with a curing agent formed from the radical copolymerization of vinyl monomers during the cure process of the epoxy resin. N-phenylmaleimide and p-acetoxystyrene were used as vinyl monomers of the curing agent. The epoxy resin was cured by the insertion reaction of the ester group of the in situ polymerized curing agent and the epoxy group of the epoxy resin. In the cure system of the epoxy and the phenol resins, reduction of the viscosity of the resin composition was achieved by replacing some or all of the phenol resin with these monomers. When all phenol resins were replaced by these monomers, the viscosity of resin composition (0.01 Pa s at 70 °C) decreased by about 1/2000 compared with that of the system with only phenol resin (21 Pa s at 70 °C). The glass transition temperature (T_g) of the cured resin with no phenols was 174 °C, an improvement of 17 °C compared with that of the system cured with only phenol resin. The flexural strength of the new resins remained unchanged.     

双酚A型含氮酚醛树脂的合成及应用研究

以双酚A、甲醛和三聚氰胺等为原料合成了含氮酚醛树脂,并对环氧树脂的阻燃改性,制得了电性能良好且阻燃性优异的阻燃环氧树脂。     

Synthesis and characterization of emulsion‐type curing agent of water‐borne epoxy resin

Self‐emulsified water‐borne epoxy curing agent of nonionic type was prepared using triethylene tetramine (TETA) and derivative of epoxy resin as a capping agent, which was synthesized by liquid epoxy resin (E51) and polyethylene glycol (PEG), and the curing agent possessed emulsification and curing properties at the same time. The curing agent with good property of emulsifying liquid epoxy resin could be obtained under the condition of the molar ratio of PEG : E51 : TETA as 0.8 : 1 : 3.5 at 80°C for 5 h. The mean particle size of the emulsion liquid was about 220 nm with the prepared curing agent and epoxy resin at the mass ratio of 1 : 3. The structure of the emulsion‐type curing agent was confirmed by FTIR and ¹H NMR spectra, and the mechanism of cured film formation was also analyzed by SEM photographs. The cured film prepared by the emulsion‐type curing agent and epoxy resin under ambient cure conditions showed good properties even at high staving temperature. This study provides useful suggestions for the application of the water‐borne epoxy resins in coating industry. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2652–2659, 2013     

Hybridization of aqueous PU/epoxy resin via a dual self‐curing process

Amino‐terminated and carboxyl‐containing polyurethane (PU) is prepared by an isocyanate‐terminated PU prepolymer process. Carboxyl‐containing epoxy resin is obtained from a half‐esterification of epoxy resin with maleic anhydride. These two aqueous resins are obtained after neutralization with triethylamine and dispersion into water phase, respectively. A latent curing agent (TMPTA‐AZ) is prepared by a Michael addition of aziridine with trimethylolpropane triacrylate (TMPTA). A self‐curing system of PU/epoxy hybrid is obtained from a blending of these two aqueous resins with latent curing agent. PU/epoxy hybrid is derived from two self‐curing reactions on drying. The first curing for hybridization between PU amino groups with oxirane groups of epoxy resin is via a ring‐opening reaction and the secondary curing takes place on carboxyl groups of PU/epoxy hybrid with aziridine of TMPTA‐AZ. The final properties of these dual self‐cured PU/epoxy hybrids are reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flame retardancy and dielectric properties of dicyclopentadiene‐based benzoxazine cured with a phosphorus‐containing phenolic resin

A dicyclopentadiene‐based benzoxazine (DCPDBZ) was prepared and separately copolymerized with melamine–phenol formaldehyde novolac or phosphorus‐containing phenolic resin (phosphorus‐containing diphenol) at various molar ratios. Their curing behaviors were characterized by differential scanning calorimetry. The electrical properties of the cured resins were studied with a dielectric analyzer. The glass‐transition temperatures were measured by dynamic mechanical analysis. The thermal stability and flame retardancy were determined by thermogravimetric analysis and a UL‐94 vertical test. These data were compared with those of bisphenol A benzoxazine and 4,4′‐biphenol benzoxazine systems. The effects of the diphenol structure and cured composition on the dielectric properties, moisture resistance, glass‐transition temperature, thermal stability, and flame retardancy are discussed. The DCPDBZ copolymerized with phosphorus‐containing novolac exhibited better dielectric properties, moisture resistance, and flame retardancy than those of the melamine‐modified system. The flame retardancy of the cured benzoxazine/phosphorus‐containing phenolic resins increased with increasing phosphorus content. The results indicate that the bisphenol A and 4,4′‐biphenol systems with a phosphorus content of about 0.6% and the dicyclopentadiene system with a phosphorus content of about 0.8% could achieve a flame‐retardancy rating of UL‐94 V‐0. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

环氧树脂/胺化酰亚胺潜伏性固化体系的制备

为了深入了解新型环氧树脂/胺化酰亚胺潜伏性固化体系的使用条件,采用差示扫描量热（DSC）技术考察了E–51型环氧树脂/脂肪族胺化酰亚胺体系的非等温固化反应过程,研究了体系的固化条件及固化物性能。结果表明：E–51与固化剂的物质的量比为1∶0.1;体系的固化条件为固化150℃/2 h,后固化180℃/1 h。树脂试样制备工艺简单,无挥发性有机溶剂,树脂混合物贮存稳定性好。体系固化反应平稳且放热量较少,完全固化后的树脂试样具有良好的耐水性、耐热性和物理机械性能。     

Synthesis of curing agent for epoxy resin based on halogenophosphazene

Epoxy resins are, due to their excellent properties (such as chemical resistance, dimensional stability, and heat resistence), widely used in practice. The basic principle of curing epoxy resins with a hardener containing multiple amino groups is the crosslinking reaction between active hydrogen atoms in the hardener and the oxirane groups in the epoxy resin. This study deals with the synthesis and characterization of hexachloro‐cyclo‐triphosphazene derivative and its subsequent use for curing epoxy resins. The new hardener was prepared from hexachloro‐cyclo‐triphosphazene by nucleophilic substitution with isophorone diamine and its curing capability was compared with original isophorone diamine. The prepared derivative hexaisophorone diamino‐cyclo‐triphosphazene (HICTP) provided advantages over conventional curing system, as it improved mechanical properties as well as the flame resistance. Testing of the cured epoxy resin during burning was carried out using dual cone calorimeter, which enables more extensive monitoring of parameters in comparison with testing using oxygen index that has been used in many publications. The epoxy resin cured with the prepared phosphorus containing HICTP exhibits lower values for total heat release, amount of smoke released and oxygen consumed, which may cause a slower flame spread. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42917.     

高性能环氧树脂基体的发展

综述了高性能环氧树脂的制备方法和性能。介绍了几种高性能的环氧树脂固化体系 ,新型的耐湿热性的环氧树脂 ,氰酸酯改性环氧树脂 ,液晶环氧树脂 ,双马来酰亚胺改性环氧树脂等     

Molecular design and properties of intrinsic flame-retardant P-N synergistic epoxy resin

In recent years, the poor weather resistance and aging resistance of additive flame retardants have caused researchers to pay attention to reactive flame retardants. A novel P-N coacting epoxy curing agent with intrinsic flame retardancy was designed and synthesized. The mechanical properties, crosslinking curing properties and flame-retardant properties of intrinsic flame-retardant epoxy resin were characterized. The results show that the cross-linking curing performance of hexa (3,5-diamino-1,2,4 triazolyl)-cyclotriphosphonitrile) (VCP) is lower than that of DDM. This is due to the decrease in cross-linking density caused by the VCP ring molecular structure. Therefore, the mechanical properties of the epoxy resin cured with VCP decreased, but the flame-retardant properties of the material significantly improved. The limiting oxygen index of the VCP/EP flame retardant epoxy thermosets was 27.3%, reaching the UL 94 V-1 level. The peak heat release rate and total heat release rate of the VCP/EP flame retardant epoxy thermosets were significantly reduced. The flame retardancy mechanism was studied by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and x-ray photoelectron spectroscopy. The results show that the intrinsic flame-retardant P-N coacting epoxy resin has excellent curing and flame-retardant properties.     

N-对羧苯基马来亚胺固化邻甲酚醛环氧树脂

合成了N-对羧基苯基马来酰亚胺,并将其用作邻甲酚醛环氧树脂的固化剂。对固化产物的热分析结果表明:N-对羧基苯基马来酰亚胺可明显提高邻甲酚醛环氧树脂的耐热性能,固化产物的起始热分解温度为278℃,分解10%时的温度为348℃,700℃时的残炭分数为45%。     

油酸对环氧树脂的改性研究

研究了油酸对环氧树脂酸酐固化物性能的影响。用简支梁冲击试验机研究了油酸对固化物耐冲击性的影响,并用热变形仪和热重分析仪研究了固化物热稳定性的变化。结果表明,适量的油酸可以提高环氧树脂固化物的韧性,对其硬度影响不大,而且当固化剂适量时则对固化物的耐热性影响很小。