Preparation and properties of halogen‐free flame‐retarded phthalonitrile–epoxy blends

Halogen‐free flame‐retarded blends composed of 2,2‐bis[4‐(3,4‐dicyanophenoxy) phenyl] propane (BAPh) and epoxy resin E‐44 (EP) were successfully prepared with 4,4′‐diaminodiphenyl sulfone as a curing additive. The structure of the copolymers was characterized by Fourier transform infrared spectroscopy, which showed that epoxy groups, a phthalocyanine ring, and a triazine ring existed. The limiting oxygen index values were over 30, and the UL‐94 rating reached V‐0 for the 20 : 80 (w/w) BAPh/EP copolymers. Differential scanning calorimetry and dynamic rheological analysis were employed to study the curing reaction behaviors of the phthalonitrile/epoxy blends. Also, the gelation time was shortened to 3 min when the prepolymerization temperature was 190°C. Thermogravimetric analysis showed that the thermal decomposition of the phthalonitrile/epoxy copolymers significantly improved with increasing BAPh content. The flexible strength of the 20:80 copolymers reached 149.5 MPa, which enhanced by 40 MPa compared to pure EP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

N-phosphorylated Iminophosphoranes based on 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and their flame-retardant behavior in epoxy resins

Two novel N-phosphorylated iminophosphoranes based on 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were evaluated as flame retardant (FR) additives. They were incorporated in two different epoxy resin systems (EP) based on diglycidyl ether of bisphenol A (DGEBA) and a novolac glycidyl ether (DEN438) both cured with dicyandiamide/fenuron (D/F). Decomposition temperatures and char yields of the cured EP were evaluated and compared to the corresponding neat EP as well as to structurally related compounds. The flame-retardant properties were investigated using the UL-94 V test and further verified with cone calorimetry. The N-phosphorylated iminophosphoranes with DOPO moieties exhibit distinctive flame-retardant effects in DGEBA/D/F and DEN438/D/F, depending on the chemical environment around the second phosphorus atom, even with low FR content. If the iminophosphorane is triphenyl phosphite based the mode of action is assigned to act mainly in the condensed phase hence being advantageous in DGEBA/D/F compared to the triphenylphosphine-based iminophosphorane, which in turn is more active in the gas phase resulting in superiority in DEN438/D/F.     

Synthesis and properties of flame‐retardant epoxy resins based on DOPO and one of its analog DPPO

Two phosphorus‐containing heterocyclic flame retardants ‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and 2,8‐dimethyl‐phenoxaphosphin‐10‐oxide (DPPO) ‐ and their derivatives were characterized and incorporated in the backbone of epoxy novolac to obtain flame‐retardant epoxy resins. The structures and spectroscopic data including high‐resolution mass spectroscopy of these flame retardants were determined. Flame‐retardant epoxy resins with a phosphorus content of up to 2% based on heterocyclic DOPO and DPPO were cured with 4,4′‐diaminodiphenylmethane (DDM), and their features were examined by UL 94, LOI, and DSC. In this manner, high‐performance polymers with glass transition temperatures around 190°C and the UL 94 rating V0 were obtained. These polymers were compared with epoxy resins incorporating diphenyl phosphite and diphenyl phosphate, which are nonheterocyclic and do not pass the UL 94 test up to 2% phosphorus. DPPO has a similar flame retardancy like the commercially available DOPO. Furthermore, to explain the difference in the efficiency of the tested flame retardants, key experiments for the determination of the active species during the flame‐retarding process were performed and the PO radical was identified. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007.     

A phosphorus‐containing phenolic derivative and its application in benzoxazine resins: Curing behavior,thermal, and flammability properties

In this work, flame‐retardant benzoxazine resins were prepared by copolymerization of bisphenol A based benzoxazine (BA‐a) and a phosphorous‐containing phenolic derivative (DOPO‐HPM). The curing behavior, thermal stability, and flame resistance of BA‐a/DOPO‐HPM composites were studied by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL94 test, and cone calorimeter. The DSC results indicated that DOPO‐HPM catalyzed the curing reaction because of its acidity. The TGA results revealed that the BA‐a/DOPO‐HPM thermosets possessed higher decomposition temperatures (T_5%) and char yields than that of BA‐a. The combustion tests indicated that the flame retardant properties of BA‐a/DOPO‐HPM thermosets were enhanced. The BA‐a/DOPO‐HPM‐20 sample acquired the highest LOI value of 32.6% and UL94 V‐0 rating. Moreover, the average of heat release rate (av‐HRR), peak of heat release rate (pk‐HRR), average of effective heat of combustion (av‐EHC) and total heat release (THR) of BA‐a/DOPO‐HPM‐20 were decreased by 24.6%, 53.1%, 14.9%, and 22.1%, respectively, compared with BA‐a. The attractive performance of BA‐a/DOPO‐HPM blends was attributed to the molecular structure of DOPO‐HPM composed of DOPO group with excellent flame‐retardant effect and phenolic hydroxyl group with catalysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43403.     

Flame retardancy effects of phosphorus‐containing compounds and cationic photoinitiators on photopolymerized cycloaliphatic epoxy resins

This study presents a promising ultraviolet (UV)‐curable epoxy resin formulation with improved flame‐retardant properties. The formulation is based on the cycloaliphatic epoxide 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexane carboxylate (ERL4221) and a novel silicon, phosphorous containing flame‐retardant additive. The additive, 1,3,5,7‐tetramethyl‐1,3,5,7‐tetra 2‐(6‐oxido‐6‐H‐dibenzo(c,e) (1,2)oxaphosphorin‐6‐yl) ethylcyclotetrasiloxane (DOPO‐SiD), was synthesized by the addition reaction of 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinylcyclotetrasiloxane (D₄Vi) with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). Formulations containing the cycloaliphatic epoxy resin ERL4221 and the flame‐retardant DOPO‐SiD additive were prepared in various concentrations and crosslinked by UV irradiation. The effects of DOPO‐SiD and photoinitiators, such as the cyclopentadienyl iron complex of carbazole (In‐Fe) and diphenyl‐(4‐(phenylthiol) phenyl) sulfonium hexafluorophosphate (In‐S), on the flame‐retardant properties and thermal stabilities of UV‐cured ERL4221/DOPO‐SiD composites were investigated with limiting oxygen index, UL‐94 vertical test, and thermogravimetric analysis, respectively. The results showed that DOPO‐SiD can increase the thermal stabilities of the ERL4221/DOPO‐SiD. The char yield was improved when DOPO‐SiD and In‐Fe were simultaneously used. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40011.     

Phosphorous‐containing epoxy resins from a novel synthesis route

The ? P(O)‐H in 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was used as an active group to react with the carbonyl group in 4,4′‐dihydroxybenzophenone (DHBP) to result a novel phosphorous‐containing biphenol compound (DOPO‐2OH). Phosphorous‐containing epoxy resins were therefore obtained from reacting DOPO‐2OH with epichlorohydrin or with diglycidylether bisphenol A. The synthesized compounds were characterized with FTIR, ¹H and ³¹P NMR, elemental analysis, and epoxide equivalent weight titration to demonstrate the their chemical structures. Cured epoxy resins were prepared via thermal curing the epoxy resins with various curing agents. Thermal analysis results (differential scanning calorimetry and thermogravimetric analysis) revealed that these cured epoxy resins exhibited high glass transition temperatures and high thermal stability. High char yields at 700°C and high LOI (limited oxygen index) values were also found for the cured epoxy resins to imply that the resins were possessing high flame retardancy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1697–1701, 2002     

Flame‐retardant,glass‐fabric‐reinforced epoxy resin laminates fabricated through a gradient distribution mode

In general, epoxy resin (EP) glue mixed with a high content of flame retardants is used to coat glass fabrics layer by layer to prepare fire‐retardant printed circuit boards (PCBs). However, the addition of the flame retardants not only increases the cost but also greatly deteriorates the processability and mechanical properties of the PCBs. In this study, a gradient distribution mode of composite flame retardants was designed and applied in EP‐based PCB composites. Unlike the traditional uniform distribution mode, in which flame retardants are evenly distributed in every resin layer, the gradient mode concentrates a higher content of the flame retardants on the surface layer, and the concentrations are gradually reduced along the thickness. In this way, the surface resin can quickly form a condensed charring barrier to hold back fire; this effectively protects the underlying resin, which has lower contents of flame retardant. The results of this study show that PCB prepared by the gradient mode obtained satisfactory flame retardance (a UL94 V‐0 rating) with only a 3.5 wt % total amount of flame retardant; this value was much lower than that (6.3 wt %) of composites featuring a uniform distribution. Additionally, the gradient mode also maintained the mechanical properties of PCB better. The tensile, impact, and flexural strengths of the gradient distribution system were obviously higher than those of the uniform distribution one with the same content of flame retardant. On the basis of the mode, a more economic and efficient technology was developed to manufacture flame‐retardant layered PCB. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44369.     

Novel phosphorus‐based flame retardants containing 4‐tert‐butylcalix[4]arene: Preparation and application for the fire safety of epoxy resins

A novel flame retardant (FR) containing phosphorus and 4‐tert‐butylcalix[4]arene was synthesized and characterized. The FR combined with ammonium polyphosphate (APP) was then incorporated into epoxy resins (EPs) at different ratios. The flame retardancy, thermal stability, and smoke‐releasing properties were investigated. The limiting oxygen index was as high as 30.8% when the mass fraction ratio of the FR to APP was 1:2. The improved FR effect have been due to the combined FR effects between the FR and APP. The char residue content at 800 °C under a nitrogen atmosphere increased notably from 8.22% to 17.6% when the FR APP was incorporated into EP; this indicated an improvement in the thermooxidation resistance. From the cone test, we found that both the total heat‐release and peak heat‐release rate of the FR resins were reduced. Compared to the resins containing no FRs, the smoke‐production rate and total smoke‐production results indicate that the FR resins also exhibited good smoke‐suppression properties. Generally, the stable char layer of the FR APP–EP not only effectively prevented the release of combustion gases but also hindered the propagation of oxygen and heat into the interior substrate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45105.     

Structure,thermal, and mechanical properties of DDM‐hardened epoxy/benzoxazine hybrids: Effects of epoxy resin functionality and ETBN toughening

Bifunctional, trifunctional, and tetrafunctional epoxy (EP) resins were hardened with stoichiometric amount of 4,4′‐diaminodiphenyl methane in presence and absence of benzoxazine (BOX). The EP/BOX ratio of the hybrid systems was constant, viz. 50/50 wt %. For the bifunctional EP, the EP/BOX range covered the ratios 75/25 and 25/75 wt %, as well. Epoxy‐terminated liquid nitrile rubber (ETBN) was incorporated in 10 wt % in the systems with trifunctional and tetrafunctional EP, and in 10, 15, and 20 wt % in the EP/BOX with bifunctional EP to improve their toughness. Information on the structure and morphology of the hybrid systems was received from differential scanning calorimetric, dynamic‐mechanical thermal analysis, atomic force microscopic, and scanning electron microscopic studies. The flexural, fracture mechanical properties, thermal degradation, and fire resistance of the EP/BOX and EP/BOX/ETBN hybrids were determined. It was found that some homopolymerized BOX was built in the EP/BOX conetwork in form of nanoscale inclusions, whereas ETBN formed micron scaled droplets of sea‐island structure. Incorporation of BOX improved the charring and fire resistance, enhanced the flexural modulus and strength, reduced the glass transition (T_g), the fracture toughness, and energy. Additional modification with ETBN decreased the charring, fire resistance, flexural modulus and strength, as well as T_g, however, improved the fracture toughness and especially the fracture energy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Phosphorus‐containing terephthaldialdehyde adducts—Structure determination and their application as flame retardants in epoxy resins

Two novel phosphorus‐rich prepolymers based on epoxy novolac and terephthaldialdehyde and potential flame retardants, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and 2,8‐dimethyl‐phenoxaphosphin‐10‐oxide (DPPO) were synthesised. The resultant flame‐retardant epoxy resins were cured with 4,4′‐diaminodiphenylmethane (DDM) and 4,4′‐diamino‐dicyclohexylmethane (PACM). Their flammability and burning behavior were characterised by UL 94 and LOI and compared with analogue prepolymers based on diethylphosphite (DEPP). The glass transition temperatures were determined by DSC measurements. Furthermore, the structures of two exemplary molecules based on p‐tolylaldehyde adducts were examined by XRD and NMR analysis to determine the possibilities of linking the two novel DOPO and DPPO derivatives to the backbone of the epoxy resin. Additionally, the char yields were determined by TG analysis and thermal desorption mass spectroscopy of the thermosets used and compared with each other to obtain more information about the possible mode of flame‐retardant action of the different phosphorus compounds. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of triphenyl phosphate flame retardant on properties of arylamine‐based polybenzoxazines

Three types of arylamine‐based benzoxazine resins modified with both condensed‐phase and gas‐phase action flame retardant, i.e. triphenyl phosphate (TPP) at various weight ratios were investigated. From rheological study, it was found that the viscosity of benzoxazines/TPP mixtures were significantly lower than that of the neat benzoxazine monomers suggesting flow property enhancement. Furthermore, differential scanning calorimetry results revealed that the onset and the maximum temperatures of the exothermic peak, due to the ring opening polymerization of benzoxazine resins, shifted to lower temperatures with increasing TPP. In addition, all polybenzoxazines possessed relatively high char yield, which increased as the TPP content increased thus enhancing their flame retardancy. The limiting oxygen index values of the flame retarded polybenzoxazines also increased with TPP addition. The maximum flame retardancy of UL94 V‐0 class was obtained with an addition of only few percents of TPP in the polybenzoxazines. Flexural strength, flexural modulus, and glass transition temperature of those polybenzoxazines tended to decrease with an addition of TPP mainly due to its plasticizing effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1074‐1083, 2013     

Synthesis of a novel azaphosphorine flame retardant and its application in epoxy resins

A novel P? C? N bond containing azaphosphorine, 5‐(4‐hydroxy)anilinomethyl‐1,3‐di(4‐hydroxy)phenyl‐1,3,5‐diazaphosphorinane (ADDPP‐OH), which could be used as both a cocuring agent and a flame‐retarding agent for epoxy resins (EPs), was synthesized from tetrakis(hydroxymethyl)phosphonium sulfate and characterized by FTIR, ¹H‐NMR, ¹³C‐NMR, ³¹P‐NMR, and so on. Compared with the pure EP, the ADDPP‐OH–EP composites showed increased decomposition temperatures and char yields. When the content of ADDPP‐OH was 10 wt %, the cured EP composite possessed a limiting oxygen index value of 33.7% and passed the V‐0 rating of the UL‐94 test. The mechanical properties of the ADDPP‐OH–EP composites was improved because of the increased crosslinking density. In addition, the morphology of the residual char indicated an intumescent and multiporous structure in the inner space and a compact and continual appearance in the outer layer; this was important in preventing the materials from burning further. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45721.     

Effects of Nickel Oxide (NiO) nanoparticles on the performance characteristics of the jatropha oil based alkyd and epoxy blends

Plant oil based alkyd resin was prepared from jatropha oil and blended with epoxy resin. Subsequently, alkyd/epoxy/NiO nanocomposites with different wt % of NiO nanoparticles have been prepared by mechanical mixing of the designed components. The structure, morphology, and performance characteristics of the nanocomposites were studied by UV‐visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and universal testing machine (UTM). The alkyd/epoxy/NiO nanocomposites showed the gradual increase in thermal stability with increasing NiO content. With 3 wt % NiO content the tensile strength of the nanocomposite increased by 19 MPa (more than twofold) when compared with the pristine polymer. Limiting oxygen index (LOI) value of the nanocomposites indicate that the incorporation of NiO nanoparticles even in 1 wt % can greatly improves the flame retardant property of the nanocomposites. This study confirms the strong influence of NiO nanoparticles on the thermal, mechanical, and flame retardant properties of the alkyd/epoxy/NiO nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41490.     

Novel strategy for molybdenum disulfide nanosheets grown on titanate nanotubes for enhancing the flame retardancy and smoke suppression of epoxy resin

A novel hybrid consisting of a molybdenum disulfide (MoS₂) coating on a titanium dioxide nanotube (TNT) surface (MoS₂–TNT) was synthesized by a hydrothermal method. The MoS₂, TNTs, and MoS₂–TNT hybrid were incorporated into epoxy resin (EP) to study their effects on its thermal performance and flame retardancy. Thermogravimetric analysis results show that the char yield at 700 °C of EP–MoS₂–TNTs was obviously increased compared with that of the EP–MoS₂ or EP–TNTs; this indicated that MoS₂–TNTs had a good carbonization effect. The limiting oxygen index, cone calorimetry, and smoke density tests showed that MoS₂–TNTs effectively improved the flame retardancy and smoke suppression of EP. This was attributed to the physical barrier effect of MoS₂ and the adsorption of TNTs. Moreover, the flame retardancy and smoke suppression of the EP–MoS₂–TNTs were better than those of the EP–MoS₂ or EP–TNTs alone with the same amount of addition; this indicated that there was a synergistic effect between MoS₂ and TNTs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46064.     

Superior thermal stability and smoke suppression of epoxy resin composites with graphene/LDH phosphorus-rich hybrids

In this article, graphene/LDH phosphorus-rich triple hybrid was prepared by a mild method and used to effectively improve the thermal stability and smoke suppression of epoxy resin (EP). The graphene was firstly reacted with hexamethylenediamine (HA) and followed by the treatment with the layered double hydroxide (LDH) and NaH₂PO₄ solutions. Compared to the unmodified graphene, the initial decomposition temperature of the triple hybrids increases significantly from 168.6 to 292.5°C. The residual carbon content is greatly improved and the residual mass is up to 84.1%. Elemental analysis reveals the content of phosphorus in EP composites is as high as 10 wt%. In flame retardancy tests, the peak heat release rate of the EP composite with 5 wt% graphene/LDH phosphorus-rich hybrids decreases to 786.15 KW/m², 41.19% drastic reduction compared to that of EP. These results indicate that the triple functionalization process effectively expands the interval distribution of heat release and makes the heat release process more gradual and spread flames smaller. The smoke production rate and total smoke production rate of EP composite with 5 wt% graphene/LDH phosphorus-rich hybrids are 0.32 m²/s and 40.91 m², which are significantly reduced by 65.22 and 57.83%, respectively. This gentle and efficient process provides a new approach to multi-functional design to improve the thermal stability and smoke suppression of resin-based composites.     

Synthesis and characterization of dicyclic silicon-/phosphorus-grafted alumina and its application in improving flame retardancy of epoxy resin

A new phosphorous/silicon/aluminum hybrid flame retardant (SAlu) was prepared by a surface grafting modification of alumina with a polymer (SDPS). The polymer was prepared by a condensation reaction between 3,9-dichloro-2,4,8,10-tetrahydroxy-3,9-diphosphate heterocyclic-3,9-dioxide [5.5] undecane (SPDPC) and diphenyldisiloxol. The structure of the SAlu was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, UV–Vis absorption, and particle size analysis. Thermogravimetric analysis showed that SPDS was grafted over 40% of the alumina surface. When introduced into epoxy resin, SAlu effectively improved the thermal stability and carbonization rate of the epoxy composites at high temperature. Carbonization studies showed that SAlu promoted formation of a ceramic-carbon coking structure with a porous morphology of aggregates, which isolate combustible materials, heat, and oxygen. These features improved the flame retardant performance of the composite. The solidified materials were evenly dispersed in the network structure to improve the elastic deformation ability and glass transition temperature of the solidified resin.     

Synthesis,thermal behavior,and cone calorimetry of organophosphorus epoxy materials

An organophosphorus epoxy resin with diglycidyl ether of bisphenol A (DGEBA), which has improved fire performance, was synthesized from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide and DGEBA. The epoxy resin was then cured with an isomeric mixture of 3,5‐diethyltoluene‐2,4‐diamine and 3,5‐diethyltoluene‐2,6‐diamine. The reaction kinetics were measured by Fourier transform IR, ¹H‐NMR, and differential scanning calorimetry. The effect of the incorporation of a phosphorus species into the epoxy network structures was also measured using thermogravimetric, thermal conductivity, and dynamic mechanical thermal analyses. The fire performance was measured using cone calorimetry, which showed that a significant improvement was achieved by the addition of only 1–4% phosphorus into the epoxy backbone. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3696–3707, 2003     

Property of intrinsic flame retardant epoxy resin cured by functional magnesium organic composite salt and diethylenetriamine

An efficient intrinsic flame retardants composite was prepared by curing epoxy resin with a functional magnesium organic composite salt (FMOCS, 0.685 ± 0.3 nm) and diethylenetriamine (DETA). Curing behavior, thermal and flame‐retardant properties of the cured epoxy resins were systematically investigated by infrared spectrum (FTIR), thermogravimetric analysis (TGA), vertical burning test (UL‐94) and limited oxygen index (LOI) measurement. It was found that flame retardancy and mechanical properties of the cured composite are significantly enhanced compared with DETA/EP. The LOI of the EP reached to 33%, which is much higher than the DETA/EP (19%) or its IFR composite (31%) in the optimal addition of ammonium polyphosphate (APP, 18.69 wt %), pentaerythritol (PER, 6.21 wt %) and FMOCS (3.50 wt %). Furthermore, the mechanical properties of the composite material measurement results to imply that it can enhance tensile strength (150%) and bending strength (88%) rather than DETA/EP, which were tested by impact testing machine and microcomputer control electron universal testing machines. Copyright © 2016 John Wiley & Sons, Ltd.     

The influence of ceramic additives on intumescence and thermal activity of epoxy coatings for steel

The article presents results of the research on the influence of graphite/kaolin and graphite/titanium oxide systems on thermal properties, intumescence degree and the integrity of the structure of intumescent protective films based on epoxy resins for steel. The TG/DTG/DSC analysis showed that graphite/kaolin system shifted the decomposition reaction of epoxy resin towards higher temperatures, even by about 30°C. Fire endurance tests and the SEM analysis confirmed these results because more thermally resistant (T_500°C reached after 37.5 min for 1.1 coating thickness), swollen (about 20 times) and homogeneous coatings were obtained. The presented results suggest that ceramic fire retardants can successfully cooperate with organic components in intumescent protective coatings for steel elements.     

Synthesis and characterization of epoxy film cured with phosphorous‐containing phenolic resin

Through the electrophilic addition reaction of ? P(O)? H and C?C, a series of novel phosphorus‐containing phenolic resins bearing maleimide (P‐PMFs) were synthesized and used as curing agent for preparing high performance and flame retardancy epoxy resins. The structure of the resin was confirmed with FTIR and elemental analysis. Thermal properties and thermal degradation behaviors of the thermosetted resin was investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The epoxy resins exhibited high glass transition temperature (143–156°C), goof thermal stability (>330°C) and retardation on thermal degradation rates. High char yields (700°C, 52.9%) and high limited oxygen indices (30.6–34.8) were observed, indicating the resins' good flame retardance for the P‐PMFs/CNE cured resins. The developed resin may be used potentially as environmentally preferable products in electronic fields. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3813–3817, 2007