Epoxy resins from novel monomers with a bis‐(9,10‐dihydro‐9‐oxa‐10‐oxide‐10‐phosphaphenanthrene‐10‐yl‐) substituent

A new diepoxide and a new diamine, both bearing bis‐(9,10‐dihydro‐9‐oxa‐10‐oxide‐10‐phosphaphenanthrene‐10‐yl‐)‐substituted methylene linkages, were prepared through the reaction of 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide with benzophenone derivatives via a simple addition reaction followed by a dehydration reaction. These two compounds were used as monomers for preparing cured epoxy resins with high phosphorus contents. The resultant epoxy resins showed high glass‐transition temperatures (between 131 and 196 °C). All of the cured epoxy resins exhibited high thermal stability, with 5% weight loss temperatures over 316 °C, and excellent flame retardancy, with limited oxygen index values of 37–50. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 359–368, 2002     

Preparation and properties of high performance epoxy–silsesquioxane hybrid resins prepared using a maleimide–alkoxysilane compound as a modifier

An alkoxysilane compound possessing maleimide moiety (MSM) was prepared from N‐(4‐hydroxyphenyl)maleimide and 3‐glycidoxypropyltrimethoxysilane and was used as a modifier of epoxy resins. In situ curing epoxy resins with MSM resulted in epoxy resins with good homogeneity. Just 5–10 wt % of MSM is sufficient to yield high glass transition temperature (165 °C), good thermal stability above 360 °C, and high flame retardancy (LOI = 30) to bisphenol‐A‐based epoxy resins. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5787–5798, 2005     

Effect of a triazine ring‐containing charring agent on fire retardancy and thermal degradation of intumescent flame retardant epoxy resins

A triazine ring‐containing charring agent (PEPATA) was synthesized via the reaction between 2,6,7‐trioxa‐l‐phosphabicyclo‐[2.2.2]octane‐4‐methanol (PEPA) and cyanuric chloride. It was applied into intumescent flame retardant epoxy resins (IFR‐EP) as a charring agent. The effect of PEPATA on fire retardancy and thermal degradation behavior of IFR‐EP system was investigated by limited oxygen index (LOI), UL‐94 test, microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) and thermogravimetric analysis/infrared spectrometry (TG‐IR). The glass transition temperatures (T_g) of IFR‐EP systems were studied by dynamic mechanical analysis (DMA). The LOI values increased from 21.5 for neat epoxy resins (EPs) to 34.0 for IFR‐EP, demonstrating improved flame retardancy. The TGA curves showed that the amount of residue of IFR‐EP system was largely increased compared to that of neat EP at 700 °C. The new IFR‐EP system could apparently reduce the amount of decomposing products at higher temperatures and promotes the formation of carbonaceous charred layers that slowed down the degradation. Copyright © 2010 John Wiley & Sons, Ltd.     

Flame‐retardant epoxy resins with high glass‐transition temperatures from a novel trifunctional curing agent: Dopotriol

A novel phosphorus‐containing trifunctional novolac (dopotriol) was synthesized through the addition reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide and rosolic acid. The structure of dopotriol was confirmed with NMR spectroscopy and elemental analyses. The dopotriol was blended with phenol novolac in the ratios of 10/0, 8/2, 6/4, 4/6, 2/8, and 0/10 to serve as a curing agent for diglycidyl ether of bisphenol A. Thermal properties, such as the glass‐transition temperature, thermal decomposition temperature, and flame retardancy, moisture absorption, and dielectric properties of the cured epoxy resins were evaluated. The activity and activation energy of curing were studied with the methods of Kissinger and Ozawa by dynamic differential scanning calorimetry scans. The glass‐transition temperatures of the cured epoxy resins were 138–159 °C, increasing with the phosphorus content. This is rarely seen in the literature after the addition of a flame‐retardant element. The flame retardancy increased with the phosphorus content, and a UL‐94 V‐0 grade was achieved with a phosphorus content of 1.87%. Similar dielectric properties and moisture absorption were observed for these phosphorus‐containing epoxy resins, and this implied that the addition of phosphorus to epoxy did not affect the dielectric properties and moisture absorption. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2862–2873, 2005     

Synthesis of a novel phosphorus‐containing curing agent and its effects on the flame retardancy,thermal degradation and moisture resistance of epoxy resins

A novel phosphorus‐containing compound diphenyl‐(1, 2‐dicarboxylethyl)‐phosphine oxide defined as DPDCEPO was synthesized and used as a flame retardant curing agent for epoxy resins (EP). The chemical structure of the prepared DPDCEPO was well characterized by Fourier transform infrared spectroscopy, and ¹H, ¹³C and ³¹P nuclear magnetic resonance. The DPDCEPO was mixed with curing agent of phthalic anhydride (PA) with various weight ratios into epoxy resins to prepare flame retardant EP thermosets. The flame retardant properties, combustion behavior and thermal analysis of the EP thermosets were respectively investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), cone calorimeter measurement, dynamic mechanical thermal analysis and thermogravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of the char residues for EP thermosets were respectively investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS). The water resistant properties of the cured EP were evaluated by putting the samples into distilled water at 70°C for 168 hr. The results revealed that the EP/20 wt% DPDCEPO/80 wt% PA thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.2%. The cone test results revealed that the incorporation of DPDCEPO effectively reduced the combustion parameters of the epoxy resin thermosets, such as heat release rate and total heat release. The dynamic mechanical thermal analysis test demonstrated that the glass transition temperature (Tg) decreased with the increase of DPDCEPO content. The TGA results indicated that the incorporation of DPDCEPO promoted the decomposition of epoxy resin matrix ahead of time and led to a higher char yield and thermal stability at high temperatures. The surface morphological structures and analysis of the XPS of the char residues of EP thermosets revealed that the introduction of DPDCEPO benefited the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resin material surface during combustion. The mechanical properties and water resistance of the cured epoxy resins were also measured. After water resistance tests, the EP/20 wt% DPDCEPO/80 wt% PA thermosets retained excellent flame retardancy, and the moisture adsorption of the EP thermosets decreased with the increase of DPDCEPO content in EP thermosets because of the existence of the P–C bonds and the rigid aromatic hydrophobic structure in DPDCEPO. Copyright © 2015 John Wiley & Sons, Ltd.     

Flame‐retardant epoxy resins from o‐cresol novolac epoxy cured with a phosphorus‐containing aralkyl novolac

A novel phosphorus‐containing aralkyl novolac (Ar‐DOPO‐N) was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) first with terephthaldicarboxaldehyde and subsequently with phenol. The chemical structures of the synthesized compounds were characterized with Fourier transform infrared, ¹H and ³¹P NMR, and elemental analysis. Ar‐DOPO‐N blended with phenol formaldehyde novolac was used as a curing agent for o‐cresol formaldehyde novolac epoxy, resulting in cured epoxy resins with various phosphorus contents. The epoxy resins exhibited high glass‐transition temperatures (159–177 °C), good thermal stability (>320 °C), and retardation on thermal degradation rates. High char yields and high limited oxygen indices (26–32.5) were observed, indicating the resins' good flame retardance. Using a melamine‐modified phenol formaldehyde novolac to replace phenol formaldehyde novolac in the curing composition further enhanced the cured epoxy resins' glass‐transition temperatures (160–186 °C) and limited oxygen index values (28–33.5). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2329–2339, 2002     

Study on liquid oxygen compatibility of bromine‐containing epoxy resins for the application in liquid oxygen tank

The liquid oxygen compatible epoxy resin was obtained by the polycondensation between tetrabromobisphenol A and neat epoxy resins. The results of liquid oxygen impact test indicated that the synthetic epoxy resins were compatible with liquid oxygen. The relationship between impact reaction sensitivity (IRS) and flame retardancy were studied by liquid oxygen impact test and limiting oxygen index test. The results showed that the flame‐retardant modification of epoxy resin was valuable to reduce the IRS. The thermal gravimetric analysis results indicated that the Br · radical was quickly released in relatively low temperature (approximately 370°C) for compatible epoxy resin. The Br · radical was a key factor to promote the epoxy resin compatible with the liquid oxygen. The X‐ray photoelectron spectroscopy was used to survey the distribution of functional groups on the surface of samples before and after impact. The results showed that the oxidation reaction and carbonization process may occur on the surface of samples after impact. The liquid oxygen compatibility mechanism is proposed in this paper. The bromine‐containing epoxy resin has the potential to be the material used in liquid oxygen tank. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal properties and flame retardancy of novel epoxy based on phosphorus‐modified Schiff‐base

Through addition reaction of Schiff‐base terephthalylidene‐bis‐(p‐aminophenol) ( DP‐1 ) and diethyl phosphite (DEP), a novel phosphorus‐modified epoxy, 4,4'‐diglycidyl‐(terephthalylidene‐bis‐(p‐aminophenol))diphosphonate ether ( EP‐2 ), was obtained. An modification reaction between EP‐2 and DP‐1 resulted in an epoxy compound, EP‐3 , possessing both phosphonate groups and C?N imine groups. The structure of EP‐2 was characterized by Fourier transform infrared (FTIR), elemental analysis (EA), ¹H, ¹³C, and ³¹P NMR analyses. The thermal properties of phosphorus‐modified epoxies cured with 4,4'‐diaminodiphenylmethane (MDA) and 4,4'‐diaminodiphenyl ether (DDE) were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The activation energies of dynamic thermal degradation (E_d) were calculated using Kissinger and Ozawa's methods. The thermal degradation mechanism was characterized using thermogravimetric analysis/infrared spectrometry (TG‐IR). In addition, the flame retardancy of phosphorus‐modified epoxy thermosets was evaluated using limiting oxygen index (LOI) and UL‐94 vertical test methods. Via an ingenious design, phosphonate groups were successfully introduced into the backbone of the epoxies; the flame retardancy of phosphorus‐modified epoxy thermosets was distinctly improved. Due to incorporation of C?N imine group, the phosphorus‐modified epoxy thermosets exhibited high thermal stabilities; the values of glass‐transition temperatures (T_gs) were about 201–210°C, the values of E_d were about 220–490 kJ/mol and char yields at 700°C were 49–53% in nitrogen and 45–50% in air. These results showed an improvement in the thermal properties of phosphorus‐modified epoxy by the incorporation of C?N imine groups. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneously improving the thermal conductive and flame retardant performance for epoxy resins thermosets by constructing core‐shell‐brush structure and distributing of MWCNTs in brush intervals

Fire safety and thermal dissipation performance of epoxy resins thermosets were critical for its application in key fields such as electronic devices. The simultaneous improvement of flame retardant and thermal conductivity properties were still a challenge. Herein, ammonium polyphosphate (APP) was firstly encapsulated with 5‐wt% epoxy resins based on APP and then surface grafted with polyurethane polymer chain, and the resulting APP with core‐shell‐brush structure was constructed. Finally, the multiwalled carbon nanotube (MWCNT) was assembled in the intervals of polymer brush on APP surface, and the prepared filler was defined as MF‐APP. Its chemical structure and morphologies were characterized and confirmed. The wettability of MF‐APP was evaluated by water contact angles tests (WCA) and MF‐APP exhibited hydrophobic property with the WCA of 138°. When 9‐wt% MF‐APP was incorporated into EP thermosets, the thermal conductive value of EP/MF‐APP achieved 1.02 Wm^?1 K^?1, and the MWCNTs concentration was only 1.8 wt% in thermosets. Compared with the previous work, the prepared EP/MF‐APP thermosets exhibited outstanding thermal conductive efficiency because of the homogeneously distribution of MWCNTs. Moreover, the samples fulfilled UL‐94 V‐0 grade during vertical burning tests with the limiting oxygen index of 30.8%. As a result, the thermal conductivity and flame retardancy of EP thermosets were simultaneously enhanced with a relatively low addition amount of MF‐APP, which would bring more chance for wider application of EP thermosets in key fields.     

Vanillin‐derived phosphorus‐containing compounds and ammonium polyphosphate as green fire‐resistant systems for epoxy resins with balanced properties

Flame retardants from vanillin when utilized together with ammonium polyphosphate (APP) yield excellent synergistic flame retardancy toward epoxy resins. Bisphenol A epoxy resins have been widely used due to their excellent mechanical properties, chemical resistance, electrical properties, adhesion, etc., while they are flammable. Environment‐friendly and bio‐based flame retardants have captured increasing attention due to their ecological necessity. In this paper, 3 bio‐based flame retardants were synthesized from abundant and more importantly renewable vanillin, and their chemical structures were determined by ¹H NMR and ¹³C NMR. They were used together with APP (an environment‐friendly commercial flame retardant) to improve the fire resistance of bisphenol A epoxy resin. With the addition APP content of 15 phr, the modified bisphenol A epoxy resin could reach UL‐94V0 rating during vertical burning test and limit oxygen index values of above 35%, but reducing APP content to 10 phr, the flame retardancy became very poor. With the total addition content of 10 phr, the epoxy resins modified by 7 to 9 phr APP and 1 to 3 phr bio‐based flame retardants with epoxy groups or more benzene rings showed excellent flame retardancy with UL‐94V0 rating and limit oxygen index values of around 29%. The T_gs of the epoxy resins could be remained or even increased after introducing bio‐based flame retardants, as the control; those of APP alone‐modified epoxy resins compromised a lot. The green synergistic flame‐retardant systems have a great potential to be used in high‐performance materials.     

Evaluation of physico-chemical properties and antimicrobial synergic effect of ceftazidime-modified chitosan

The aim of this work was to study the effect of tris(3-nitrophenyl) phosphine (NPPh3), which showed a good thermal stability and carbon-forming ability, on the flame retardancy and thermal degradation mechanism of epoxy resins. A series of diglycidyl ether of bisphenol A (DGEBA) loaded with tris(3-nitrophenyl) phosphine (NPPh3) were prepared. It was found that NPPh3 can effectively improve the flame retardancy and thermal stability of the composites. When the loading amount of NPPh3 was 14%, the LOI value of the DGEBA composites was 29.2% (about 1.53 times the corresponding value of the original DGEBA resin). Thermal stability was studied by thermogravimetric analysis, and the results showed that the addition of NPPh3 can improve char formation of this system both in nitrogen and in air atmosphere. Specifically, its combustion residue at 800 °C in nitrogen atmosphere was about 4.26 times of the original resin. Differential scanning calorimetry indicated that NPPh3 slightly decreased the glass transition temperature of epoxy resins. Additionally, the gaseous degradation products were analyzed by thermogravimetric analysis/infrared spectrometry, providing insight into the thermal degradation mechanism. Scanning electron microscopy and Fourier transform infrared were brought together to evaluate the morphology and structure of the residual char obtained after combustion.     

Crosslinking of a polyacrylate bearing a spiroorthoester pendant group with mixtures of diglycidyl ether of bisphenol A and phosphorus‐containing glycidyl derivatives

The cationic crosslinking of a polyacrylate bearing a spiroorthoester pendant group with mixtures of diglycidyl ether of bisphenol A and three phosphorus‐containing glycidyl derivatives was carried out with ytterbium triflate as an initiator. The curing process was monitored with Fourier transform infrared spectroscopy. The thermomechanical and thermogravimetric properties were evaluated. The glass transition temperatures of the obtained materials were, in general, above 100 °C. The incorporation of phosphorus into the network increased the limiting oxygen index values, thus improving the flame retardancy of the materials. During crosslinking, all the crosslinked polymers showed slight shrinkage that was much lower than that observed in conventional epoxy resins. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1920–1930, 2007     

Liquid oxygen compatibility and thermal stability of bisphenol A and bisphenol F epoxy resins modified by DOPO

Bisphenol A and bisphenol F epoxy resins (BA and BF) were chemically modified by 9,10‐Dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide to improve their liquid oxygen compatibility. The structures of the modified epoxy resins were confirmed by Fourier transform infrared spectroscopy. Significant enhancement of liquid oxygen compatibility for the modified resins was detected according to the liquid oxygen mechanical impact test. Thermogravimetric analysis showed that during the degradation in oxygen atmosphere, the modified resins exhibited much lower weight loss rate and possessed much higher char residues than the control ones. Based on limited oxygen index test, better flame retardancy was also observed for the modified resins. In addition, the modified BA system was more excellent than the modified BF system in liquid oxygen compatibility, thermal stability, and flame retardancy. X‐ray photoelectron spectroscopy analysis showed that after the liquid oxygen impact, the modified resins was still in oxidation stage and the control ones already begun to decompose and char. It could be attributed to formation of the phosphoric oxyacid on the surface of the modified resins, which prevented decomposition and inhibited the reaction between the specimen and liquid oxygen. Copyright © 2014 John Wiley & Sons, Ltd.     

磷系阻燃环氧树脂研究

本文对近年来国内外9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物（DOPO）衍生物的合成及其应用于阻燃环氧树脂的方法进行介绍，并对所显示的阻燃性、热性能等作了概述和比较。将反应型磷系阻燃剂DOPO衍生物引入环氧树脂基体结构中形成阻燃持久、无卤、低烟、无毒、热稳定性好的新型含磷环氧树脂。     

Flame‐retardant epoxy resins with high glass‐transition temperatures. II. Using a novel hexafunctional curing agent: 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐yl‐tris(4‐aminophenyl) methane

We synthesized a novel phosphorus‐containing triamine [9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐yl‐tris(4‐aminophenyl) methane (dopo‐ta)] from the nucleophilic addition of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide and pararosaniline chloride, using triethylamine as an acid receiver. We confirmed the structure of dopo‐ta by IR, mass, and NMR spectra and elemental analysis. dopo‐ta served as a curing agent for diglycidyl ether of bisphenol A (DGEBA) and dicyclopentadiene epoxy (hp7200). Properties such as the glass‐transition temperature (T_g), thermal decomposition temperature, flame retardancy, moisture absorption, and dielectric properties of the cured epoxy resins were evaluated. The T_g's of cured DGEBA/dopo‐ta and hp7200/dopo‐ta were 171 and 190 °C, respectively. This high T_g phenomenon is rarely seen in the literature after the introduction of a flame‐retardant element. The flame retardancy increased with the phosphorus content, and a UL‐94 V‐0 grade was achieved with a phosphorus content of 1.80 wt % for DGEBA/dopo‐ta/diamino diphenylmethane (DDM) systems and 1.46 wt % for hp7200/dopo‐ta/DDM systems. The dielectric constants for DGEBA/dopo‐ta and hp7200/dopo‐ta were 2.91 and 2.82, respectively, implying that the dopo‐ta curing systems exhibited low dielectric properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5971–5986, 2005     

Development of novel phosphorus‐containing epoxy resins from renewable resources

Novel biobased epoxy resins were prepared from two fatty acid derivatives; epoxidized 10‐undecenoyl triglyceride and epoxidized methyl 3,4,5‐tris(10‐undecenoyloxy)benzoate, with 4,4′‐diaminodiphenylmethane as a crosslinking agent. The flame retardancy of these epoxy resins was improved by the addition of 10‐[2′, 5′‐bis(9‐oxiranyl‐nonayloxy)phenyl]‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide and by crosslinking with a phosphorus‐containing curing agent, bis(m‐aminophenyl)methylphosphine oxide. The thermal, thermomechanical, and flame‐retardant properties of the cured materials were measured with differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and the limiting oxygen index. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6717–6727, 2006     

Preparation,thermal properties,and flame retardance of epoxy–silica hybrid resins

A novel epoxy system was developed through the in situ curing of bisphenol A type epoxy and 4,4′‐diaminodiphenylmethane with the sol–gel reaction of a phosphorus‐containing trimethoxysilane (DOPO–GPTMS), which was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) with 3‐glycidoxypropyltrimethoxysilane (GPTMS). The preparation of DOPO–GPTMS was confirmed with Fourier transform infrared, ¹H and ³¹P NMR, and elemental analysis. The resulting organic–inorganic hybrid epoxy resins exhibited a high glass‐transition temperature (167 °C), good thermal stability over 320 °C, and a high limited oxygen index of 28.5. The synergism of phosphorus and silicon on flame retardance was observed. Moreover, the kinetics of the thermal oxidative degradation of the hybrid epoxy resins were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2354–2367, 2003     

Synthesis of novel boron‐containing epoxy–novolac resins and properties of cured products

Epoxy–novolac resins were synthesized by modifying a commercial novolac resin with epichlorohydrin. These epoxy–novolac resins were characterized and further modified with different contents of bis(benzo‐1,3,2‐dioxa‐borolanyl)oxide or bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxa‐borolanyl)oxide. The boron‐containing epoxy–novolac resins were autocatalytically crosslinked or crosslinked with BF₃MEA and their thermal stability and flame retardancy were determined by thermogravimetric analysis and limiting oxygen index (LOI) values. These LOI values for the bis(benzo‐1,3,2‐dioxa‐borolanyl)oxide derivatives were higher than the boron‐free novolac resins, which shows the benefit of the presence of boron. To test the role of boron in the enhancement of flammability, scanning electronic microscopy and energy‐dispersive X‐ray spectroscopy images were made. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6332–6344, 2006     

Flame retardant epoxy resins based on diglycidyloxymethylphenylsilane

Silicon‐containing epoxy resins were prepared from diglycidyloxymethylphenyl silane (DGMPS) and diglycidylether of bisphenol A (DGEBA) by crosslinking with 4,4′‐diaminodiphenylmethane (DDM). Several DGMPS/DGEBA molar ratios were used to obtain materials with different silicon contents. Their thermal, dynamomechanical, and flame‐retardant properties were evaluated and related to the silicon content. The weight loss rate of the silicon‐containing resins is lower than that of the silicon free resin. Char yields under nitrogen and air atmospheres increase with the silicon content. The LOI (limited oxygen index) values increased from 24 for a standard commercial resin to 36 for silicon‐containing resins, demonstrating improved flame retardancy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5580–5587, 2006     

Synthesis and properties of phosphorus-containing epoxy resins by novel method

Novel phosphorus-containing epoxy resins (1–3% phosphorus content) were synthesized by the reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and the diglycidyl ether of bisphenol A and then cured with 4,4′-diaminodiphenyl sulfone or phenol novolac. Differential scanning calorimetry, high performance liquid chromatography, and epoxide equivalent weight titration were used to trace the reaction between the DOPO and the epoxy. The thermal stability and flame retardancy were checked by thermal gravimetric analysis, the limiting oxygen index, and the UL-94 vertical test. The glass transitions were measured by dynamic mechanical analysis. The relation between these properties (thermal stability, flame retardancy, and glass transition) and the DOPO contents (phosphorus content) were discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3903–3909, 1999