The properties of epoxy–imide resin cured by cyclic phosphine oxide diacid

A new phosphorylated epoxyimide polymer synthesized was obtained using diimide-diepoxide (DIDE) resin cured with the new curing agent, 10-phenylphenoxa-phosphine-3,8-dicarboxylic acid-10-oxide (PCAO). In addition, compositions of the synthesized diimide-diepoxide (DIDE), Epon 828, with common curing agents, e.g., 4,4′-diaminodiphenylether (DDE) and 4,4′-diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity and heat, and flame retardation with that of (PCAO). The reactivities of those curing agents toward the two kinds of epoxy resins, as measured by differential scanning calorimetry (DSC), were in the following order: DDE> PCAO> DDS. Through evaluation of thermal gravimetric analysis (TGA), the thermal and flame resistances of epoxy polymers were confirmed in this study as capable of being significantly improved through introduction of imide and cyclic phosphine oxide group into the epoxide and curing agent structures. © 1996 John Wiley & Sons, Inc.     

Structure characterization,reactivity, and thermal properties of new cyclic phosphine oxide epoxy resin containing tetra-oxirane rings

A new type of epoxy resin, which contained cyclic phosphine oxide and tetra-oxirane rings in the main chain, was synthesized. The structure of the new type of epoxy resin was confirmed by elemental analyses (EA), infrared (IR) spectroscopy, and ¹H nuclear magnetic resonance (NMR) and ¹³C-NMR spectroscopies. In addition, compositions of the new synthesized cyclic phosphine oxide epoxy resin (TGCAO) with three curing agents, for example, bis(3-aminophenyl)ethylphosphine oxide (BEMP), 4,4′-diaminodiphenylmethane (DDM), and 4,4′-diaminodiphenylsulfone (DDS) were used for making a comparison of its curing reactivity, heat, and flame retardancy with those of Epon 828 and DEN438. The reactivities were measured by differential scanning calorimetry. Through the evaluation of thermal gravimetric analysis, those polymers, which were obtained through the curing reactions between the new epoxy resin and three curing agents (BEMP, DDM, and DDS), also demonstrated adequate thermal propeties, as well as a high char yield. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1397–1409, 1998     

Syntheses,structure, reactivity,and thermal properties of epoxy–imide resin cured by phosphorylated triamine

A new phosphorylated epoxy–imide polymer was obtained using diimide–diepoxide (DIDE) cured with tris(3-aminophenyl)phosphine oxide (TAPO). In addition, compositions of the synthesized diimide diepoxide (DIDE), Epon 828, and DEN 438 with common curing agents, e.g., 4,4′-diaminodiphenyl ether (DDE) and 4,4′-diaminodiphenylsulfone (DDS), were compared as to curing reactivity and heat and flame retardation with that of tris(3-aminophenyl)phosphine oxide. The reactivities of those curing agent toward the three kinds of epoxy resins, as measured by differential scanning calorimetry (DSC), were in the order DDE > TAPO > DDS. Through thermal gravimetric analysis (TGA), the thermal and flame resistances of epoxy were confirmed in this study as capable of being significantly improved through introduction of imide and phosphorus groups into the epoxide structure. © 1996 John Wiley & Sons, Inc.     

The synthesis and properties of new epoxy resin containing phosphorus and nitrogen groups for flame retardancy

A new type of epoxy resin, which contained phosphorus oxide and nitrogen groups in the main chain, was synthesized. The structure of the new type of epoxy resin was confirmed by infrared (IR) spectroscopy, ¹H nuclear magnetic resonance (¹H‐NMR), and ¹³C‐NMR spectroscopic techniques. In addition, compositions of the new synthesized epoxy resin (TGDMO) with three curing agents, for example, bis(3‐aminophenyl) methylphosphine oxide (BAMP), 4,4′‐diaminodiphenylmethane (DDM), and 4,4′‐diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardancy with that of Epon 828 and DEN 438. The reactivities were measured by differential scanning calorimetry (DSC). Through the evaluation of thermal gravimetric analysis (TGA), those polymers which were obtained through the curing reactions between the new epoxy resin and three curing agents (BAMP, DDM, and DDS) also demonstrated excellent thermal properties as well as a high char yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 413–421, 1999     

Novel flame retardant epoxy resins I: Synthesis, characterization, and properties of aryl phosphinate epoxy ether cured with diamine

Summary A novel aryl phosphinate epoxy ether, 10-(2',5'-bis(glycidyloxy)phenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DHQEP), was synthesized. The structures of the obtained compounds were confirmed by mass, FTIR, ¹H, ¹³C, ³¹P-NMR spectroscopies, elemental analysis, and X-ray single crystal analysis. In addition, compositions of DHQEP with common curing agents, e.g., 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenyl sulfone (DDS), and dicyanodiamide (DICY), were studied to compare their thermal and flame resistance with that of commercial epoxy resins. The aryl phosphinate epoxy-resin composites exhibited excellent thermal properties and a quite high limiting oxygen index (LOI) value as well as high char yield. Aryl phosphinate epoxy ether is shown to be an effective flame retardant and thermal stabilizer for epoxy resins. Received: 13 April 1998/Revised version: 8 May 1998/Accepted: 11 May 1998     

Properties of cyclic phosphine oxide epoxy cured by diacids and anhydride

New phosphorylated epoxy polymers were obtained with a cyclic phosphine oxide epoxy, 10‐phenylphenoxaphosphine‐3,8‐diglycidylester‐10‐oxide (EPCAO), cured with three types of curing agents: N,N′‐(4,4′‐diphenylsulfone)bis(trimellitimide) (DIDA), 10‐phenylphenoxaphosphine‐3,8‐dicarboxylic acid‐10‐oxide (PACO), and phthalic anhydride (PA). In addition, compositions of the new EPCAO synthesized with these three curing agents (DIDA, PACO, and PA) were used to make a comparison of EPCAO's curing reactivities and heat and flame retardancy with those of Epon828 and DEN438. The reactivities were measured by differential scanning calorimetry. Through the evaluation of thermogravimetric analysis, those polymers that were obtained through the curing reactions between the cyclic phosphine oxide epoxy resin and the three curing agents mentioned also demonstrated excellent thermal properties and a high char yield. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 950–961, 2002; DOI 10.1002/app.10146     

Phosphorus-containing epoxy for flame retardant. III: Using phosphorylated diamines as curing agents

Two phosphorus-containing diamine compounds, bis(4-aminophenoxy)-phenyl phosphine oxide and bis(3-aminophenyl)phenyl phosphine oxide, were synthesized for use as curing agents of epoxy resins. Phosphorylated epoxy resins were obtained by curing Epon 828 and Eponex 1510 with these two diamine agents. For raising the phosphorus contents of the resulting epoxy resins, the phosphorus-containing epoxy, bis(glycidyloxy)phenyl phosphine oxide (BGPPO), was also used. These two diamine agents showed similar reactivity toward epoxies. Their reactivities were higher than DDS and lower than DDM. High char yields in TGA evaluation were found for all the phosphorylated epoxy resins, implying their high flame retardancy. The excellent flame-retardant properties of these phosphorylated epoxy resins were also demonstrated by the high limiting oxygen index (LOI) values of 33 to 51. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 895–901, 1997     

Curing of epoxy resins with 1-[di(2-chloroethoxyphosphinyl) methyl]-2,4-and -2,6-diaminobenzene

Fire-resistant compositions were prepared using 1-[di(2-chloroethoxyphosphinyl)methyl]-2,4- and -2,6-diaminobenzene (DCEPD) as a curing agent for typical epoxy resins such as EPON 828 (Shell), XD 7342 (Dow), and MY 720 (Ciba Geigy). In addition, compositions of these three epoxy resins with common curing agents such as m-phenylenediamine (MPD) or 4,4′-diaminodiphenyl-sulfone (DDS) were studied to compare their reactions with those of DCEPD. The reactivity of the three curing agents toward the epoxy resins, measured by differential scanning calorimetry (DSC), was of the order MPD > DCEPD > DDS. The relatively lower reactivity of DCEPD toward epoxy resins was attributed to electronic effects. It was shown that the heat of polymerization (ΔH_pol) increases with increasing epoxy functionality of the resin. The polymers obtained were characterized by DSC, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier-transform infrared (FT-IR). The polymers of DCEPD showed a relatively lower polymer decomposition temperature (PDT) and a higher char yield than the polymers of the common curing agents. Furthermore, it was shown that the thermal characteristics of the compositions were dependent upon the ratio of the reactants. The fire resistance of the polymers was evaluated by determining their limiting oxygen index (LOI) value. The DCEPD polymers, especially those with polyfunctional epoxy resins, showed a significantly higher fire resistance as compared with those polymers of common curing agents.     

A simple imide compound as a curing agent for epoxy resin. I. Synthesis and properties

A simple imide compound, 4‐amino‐phthalimide (APH), was synthesized as a curing agent for epoxy resin. APH was prepared from the hydration of 4‐nitro‐phthalimide, which was prepared from the nitration of phthalimide. The chemical structure of APH was verified by IR and ¹H‐NMR spectra. The thermal properties and dielectric constant (ε) of a phosphorus‐containing novolac epoxy resin cured by APH were determined and compared with those of epoxy resins cured by either 4,4′‐diamino diphenyl methane (DDM) or 4,4′‐diamino diphenyl sulfone (DDS). The results indicate that the epoxy resin cured by APH showed better thermal stability and a lower ε than the polymer cured by either DDM or DDS. This was due to the introduction of the imide group of APH into the polymer structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Reaction kinetics and thermal properties of epoxidised cresol novolac/4,4′‐diglycidyl (3,3′,5,5′‐tetramethylbiphenyl) epoxy resin composite cured with aromatic diamine

A series of novel composites based on different ratios of epoxidised cresol novolac (ECN) and 4,4′‐diglycidyl(3,3′,5,5′‐tetramethylbiphenyl) epoxy resin (TMBP) have been prepared with the curing agent 4,4′‐methylenediamine (DDM) and 4,4′‐diaminodiphenylsulfone (DDS), respectively. The investigation of cure kinetics was performed by differential scanning calorimetry using an isoconversional method. The high thermal stabilities of the cured samples were also studied by thermogravimetric analysis. In addition, no phase separation was observed for cured ECN/DDM and ECN/DDS blending with different amounts of TMBP by dynamic mechanical analysis and scanning electron microscopy. Moreover, the cured systems also exhibited excellent impact properties and low moisture absorption. All the results indicate that the ECN/TMBP/DDM and ECN/TMBP/DDS systems are promising materials in electronic packaging. Copyright © 2011 Society of Chemical Industry     

新型耐热环氧单体的合成及性质研究

报道了一种含萘芳香酯型环氧单体二（4-（2,3-环氧丙氧基）苯甲酸）．2,7-萘4,4-二酯（P4）的合成及性质研究。利用FT-IR、1HNMR、质谱等分析测试方法对P4目标化合物的结构进行了表征。并用4,4．二氨基二苯基砜（DDS）和4,4-二氨基二苯基甲烷（DDM）两种芳香二胺固化剂对P4进行非等温固化研究。由结果可知,DDM／P4的固化峰温度为140℃,DDS／P4的固化峰温度为210℃,DDM能显著降低P4的固化温度。最后,通过对P4／DDM和环氧E20／DDM这两种固化物的热失重研究表明P4／DDM固化物具有较高的热稳定性。     

Improving thermal and flame‐retardant properties of epoxy resins by a novel reactive phosphorous‐containing curing agent

In an attempt to improve thermal and flame‐retardant properties of epoxy resins efficiently, a new reactive phosphorus‐containing curing agent called 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐(phenylimino)‐(4‐hydroxyphenyl)me‐thane (DOPO‐PHM) was synthesized and was combined with 4,4′‐diaminodiphenyl methane (DDM) to co‐cure epoxy resins (E51), which covalently incorporated halogen‐free DOPO organ groups into the epoxy networks. The chemical structure of this curing agent was confirmed by FTIR, 1D, and 2D NMR spectra. A reaction mechanism during the preparation was proposed, and the electron effect on the stabilization of the carbocation was discussed. Various DDM/DOPO‐PHM molar ratios were used to get the materials with different phosphorus contents. Their dynamic mechanical, thermal, and flame‐retardant properties were evaluated by dynamic mechanical thermal analysis, thermogravimetric analysis, and limiting oxygen index (LOI) respectively. All samples had a single T_g, showing that these epoxy resins were homogeneous phase for long‐term use in spite of adding DOPO‐PHM. Both char yields (under nitrogen and air atmospheres) increased with the increasing of phosphorus content and the LOI values increased from 24.5 for standard resin to 33.5 for phosphorus‐containing resins, indicating the significant enhancement of thermal stability and flame retardancy. POLYM. ENG. SCI., 54:1192–1200, 2014. © 2013 Society of Plastics Engineers     

Glass fiber-reinforced epoxy composites

Glass fiber-reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethane

1 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane.

(TGDDM) and tetraglycidyl bis(o-toluidino)-methane

2 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-bis(o-toluidino)methane.

(TGMBT) using various amines like 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.     

Phosphorus‐containing epoxy resin for an electronic application

A phosphorus‐containing epoxy resin, 6‐H‐dibenz[c,e][1,2] oxaphosphorin‐6‐[2,5‐bis(oxiranylmethoxy)phenyl]‐6‐oxide (DOPO epoxy resin), was synthesized and cured with phenolic novolac (Ph Nov), 4,4′‐diaminodiphenylsulfone (DDS), or dicyandiamide (DICY). The reactivity of these three curing agents toward DOPO epoxy resin was found in the order of DICY > DDS > Ph Nov. Thermal stability and the weight loss behavior of the cured polymers were studied by TGA. The phosphorus‐containing epoxy resin showed lower weight loss temperature and higher char yield than that of bisphenol‐A based epoxy resin. The high char yields and limiting oxygen index (LOI) values as well as excellent UL‐94 vertical burn test results of DOPO epoxy resin indicated the flame‐retardant effectiveness of phosphorus‐containing epoxy resins. The DOPO epoxy resin was investigated as a reactive flame‐retardant additive in an electronic encapsulation application. Owing to the rigid structure of DOPO and the pendant P group, the resulting phosphorus‐containing encapsulant exhibited better flame retardancy, higher glass transition temperature, and thermal stability than the regular encapsulant containing a brominated epoxy resin. High LOI value and UL‐94 V‐0 rating could be achieved with a phosphorus content of as low as 1.03% (comparable to bromine content of 7.24%) in the cured epoxy, and no fume and toxic gas emission were observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 353–361, 1999     

Torsional braid analysis of the aromatic amine cure of epoxy resins

The cure behavior of diglycidyl ether of bisphenol A (DGEBA) type of epoxy resins with three aromatic diamines, 4,4′-diaminodiphenyl methane (DDM), 4,4′-diaminodiphenyl sulfone (44DDS), and 3,3′-diaminodiphenyl sulfone (33DDS) was studied by torsional braid analysis. For each curing agent the stoichiometry of the resin mixtures was varied from a two to one excess of amino hydrogens per epoxy group to a two to one excess of epoxy groups per amino hydrogen. Isothermal cures of the resin mixtures were carried out from 70 to 210°C (range depending on epoxy—amine mixture), followed by a temperature scan to determine the glass transition temperature (T_g). The times to the isothermal liquid-to-rubber transition were shortest for the DDM mixtures and longest for the 44DDS mixtures. The liquid-to-rubber transition times were also shortest for the amine excess mixtures when stoichiometry was varied. A relatively rapid reaction to the liquid-to-rubber transition was observed for the epoxy excess mixtures, followed by an exceedingly slow reaction process at cure temperatures well above the T_g. This slow process was only observed for epoxy excess mixtures and eventually led to significant increases in T_g. Using time—temperature shifts of the glass transition temperature vs. logarithm of time, activation energies approximately 50% higher were derived for this process compared to those derived from the liquid-to-rubber transition. The rate of this reaction was virtually independent of curing agent and was attributed to etherification taking place in the epoxy excess mixtures. © 1994 John Wiley & Sons, Inc.     

Improvement of Elastic Modulus and Thermal Stability of Epoxy Resin Using New Curing Agents

New curing agents 2,5-diamino-1,3,4-thiadiazole (DATD) and N-(4-hydroxybenzal) N'(4′-hydroxyphenyl) thiourea (HHPT) were synthesised and characterized using FT-IR, 1H-NMR and 13C-NMR analysis. The curing reactions were studied for the epoxy resin diglycidyl ether of bisphenol-A (DGEBA) using new curing agents along with the conventional aromatic diamine 4,4′-diamino diphenyl methane (DDM) for comparison purpose. The curing profiles of DDM, DATD and DATD/HHPT towards DGEBA were examined by Differential Scanning Calorimetry (DSC). Elastic modulus and thermal stability of the cured resins were evaluated using DMA and TGA analysis. When compared with DDM and DATD, the DATD/HHPT curing system accelerated the curing rate due to the presence of phenol molecules in the HHPT. Furthermore, the DATD/HHPT-cured epoxy resin demonstrated higher elastic modulus along with better thermal stability.     

Multifunctional epoxy resins

The curing behavior of epoxy resins prepared by reacting epichlorohydrin with 4,4′-diaminodiphenyl methane (DADPM)/4,4′-diaminodiphenyl ether (DADPE) or 4,4′-diaminodiphenyl sulfone (DDS) was investigated using DDS and tris-(m-aminophenyl)phosphine oxide (TAP) as curing agents. A broad exothermic transition with two maxima were observed in the temperature range of 100–315°C when TAP was used as the curing agent. The effect of varying DDS concentration on curing behavior of epoxy resin was also investigated. Peak exotherm temperature (T_exo) decreased with increasing concentration of DDS, whereas heat of curing (ΔH) increased with an increase in amine concentration up to an optimum value and then decreased. Thermal stability of the resins, cured isothermally at 200°C for 3 h, was investigated using thermogravimetric analysis in a nitrogen atmosphere. Glass fiber-reinforced multifunctional epoxy resin laminates were fabricated and the mechanical properties were evaluated. © 1993 John Wiley & Sons, Inc.     

Morphology,thermal and mechanical performance of epoxy/polysulfone composites improved by curing with two different aromatic diamines

Epoxy/polysufone (PSF) composites cured with 4,4'-diaminodiphenyl sulfone (DDS) and 4,4'-diaminodiphenyl methane (DDM) were fabricated, and the effect of dual curing reaction of diamines with epoxy on morphology, mechanical, and thermal performance was investigated. DSC results indicated that DDM was more reactive than DDS and the activation energy decreased with the rising of DDM content. Structures with small domain size at the early stage of phase separation were fixed by the fast epoxy-DDM reaction. When the DDM content was elevated to a high level, large dual structures were changed to fine bicontinuous structures, which was favorable to improve the mechanical property. The mechanical performance of epoxy composites was enhanced and the maximum values were achieved when the DDM/DDS ratio was located at 75/25 (PSF/DDS0.25-DDM0.75). The flexural and tensile strength relative to epoxy/DDM system were enhanced more than those relative to epoxy/DDS, while the increase in toughness was the opposite. TGA measurement showed that thermal stability of epoxy/PSF composites was improved because of the restricting effect of continuous PSF domains on thermal motion of epoxy. DMA analysis exhibited two relaxation peaks for PSF/DDS0.25-DDM0.75, which could be attributed to the formation of phase separated morphology and epoxy network with different cross-link density.     

Synthesis, characterization and properties of tetramethyl stilbene-based epoxy resins for electronic encapsulation

Two novel tetramethyl stilbene-based novolac (II and IV) were synthesized from 2,6-dimethyl phenol and chloroacetaldehyde dimethylacetal or chloroacetone, and then the resulted novolacs were epoxidized to tetramethyl stilbene-based epoxy resins (III and V). The proposed structures were confirmed by FTIR, elemental analysis, mass spectra, NMR spectra and epoxy equivalent weight titration. The synthesized tetramethyl stilbene-based epoxy resins were cured with 4,4-diaminodiphenyl methane (DDM) and 4,4-diaminodiphenyl sulfone (DDS). Thermal properties of cured epoxy resins were studied using dynamic mechanical analyzer, differential scanning calorimeter, thermal expansion analyzer and thermal gravimetric analyzer (TGA). These data were compared with that of the commercial tetramethyl biphenol (TMBP) epoxy system. According to the experimental data, the order of T_g for cured epoxy system is III>TMBP>V. The order of moisture absorption for cured epoxy system is V<III<TMBP. According to TGA, the 5% degradation temperatures in nitrogen atmosphere were in the range 370-377 and 397-412 °C for DDM and DDS curing systems, respectively. In air atmosphere, the 5% degradation temperatures were in the range 372-385 and 410-411 °C for DDM and DDS curing systems, respectively. The CTE is in inverse order with T_g, therefore, III/DDS<TMBP/DDS<V/DDS.     

Cure kinetics of multifunctional epoxies with 2,2′‐dichloro‐4,4′‐diaminodiphenylmethane as hardener

The curing behavior of the epoxy resin N,N,N′,N′‐tetraglycidyldiaminodiphenyl methane (TGDDM) with triglycidyl p‐aminophenol as a reactive diluent was investigated using 2,2′‐dichloro‐4,4′‐diaminodiphenylmethane (DCDDM) as the curing agent. The effect of the curing agent on the kinetics of curing, shelf‐life, and thermal stability in comparison with a TGDDM‐diaminodiphenylsulfone (DDS) system was studied. The results showed a lesser activation energy at the lower level of conversion with a broader cure exotherm for the epoxy‐DCDDM system in comparison with the epoxy‐DDS system, although the overall activation energy for the two systems was comparable. TGA studies showed more stability in the epoxy‐DCDDM system than in the epoxy‐DDS system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2097–2103, 2000