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.     

Rheological study of the curing kinetics of epoxy–phenol novolac resin

The curing reaction of an epoxy–phenolic resin under different conditions was monitored using rheological measurements. The evolution of viscoelastic properties, such as storage modulus, G′, and loss modulus, G″, was recorded. Several experiments were performed to confidently compare the rheological data obtained under varied curing conditions of temperature, catalyst concentration, and reactive ratios. The values of G′ measured at the end of the reactions (at maximum conversion) were independent of the frequency and temperature of the tests in the range of high temperatures investigated. The overall curing process was described by a second‐order phenomenological rheokinetic equation based on the model of Kamal. The effects of the epoxy‐to‐phenolic ratio as well as the curing temperature and the catalyst concentration were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4430–4439, 2006     

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     

Kinetics modeling of a modified epoxy–amine formulation cured by thermal and microwave energy

The reaction kinetics of a rubber-modified epoxy formulation cured by microwave or thermal energy were investigated. Two phenomenological models were developed to predict the time and temperature dependence of the conversion for the neat and the modified systems. Good agreement was observed between the kinetic models and experimental results generated by chromatographic and calorimetric techniques. The same kinetic behavior was observed whatever the curing process (conventional or microwave heating). © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 543–552, 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     

Influence of the network structure and void content on hygrothermal stability of resol resin modified with epoxy–amine

Epoxy–amine was blended with two resol resins to study the influence of the final network and void content on the water absorption of these systems. To characterize the network structure of the blends, infrared analyses were performed. It was observed that a diminution in the crosslink density of the network and the reaction between the epoxy and resol have been occurred. From dynamic–mechanical analyses, a diminution in the T_g value and an increment in the height of the tan δ peak with the epoxy–amine content added to the resol were observed. Thermogravimetric analysis showed that the thermal stability of the resol was reduced by the addition of epoxy–amine as well as a lesser crosslink network for the blends with higher epoxy–amine content. The maximum water uptake and the diffusion coefficient were related with the chemical structure and void content of the specimens. On one hand, the maximum water uptake was observed to depend on the void content of the blends. On the other hand, the diffusion coefficient appears to be related with the local motions of the polymeric chains and with the hydrophilic character of the materials. This behavior was observed for the two resols studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 588–597, 2006     

Synthesis of polyurethane–imide (PU–imide) copolymers with different dianhydrides and their properties

This study reports the synthesis of polyurethane–imide (PU–imide) copolymers using 4,4′-diphenylmethane diisocyanate (MDI) polytetramethylene glycols (PTMGs) and different aromatic dianhydrides. Differential scanning calorimetry (DSC) results indicate that PU–imide copolymers had two phase structures containing four transition temperatures (T_gs, T_ms, T_gh and T_mh). However, only PU–imide copolymers were formed by soft PTMG(2000) segments possessing a T_ms (melting point of soft segment). When different aromatic dianhydrides were introduced into the backbone chain of the polyurethane, although the T_gs (glass transition temperature of the soft segment) of some of PU–imide copolymers did not change, the copolymers with long soft segments had low T_gs values. The T_gh (glass transition temperature of hard segment) values of PU–imide copolymers were higher than that of polyurethane (PU). In addition, the high hard segment content of PU–imide copolymer series also had an obvious T_mh (melting point of hard segment). According to thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA), the PU–imide copolymers had at least two stages of degradation. Although the T_di (initial temperature of degradation) depended on the hard segment content and the composition of hard segment, the different soft segment lengths did not obviously influence the T_di. However, PU–imide copolymers with a longer soft segment had a higher thermal stability in the degradation temperature range of middle weight loss (about T_d 5%–50%). However, beyond T_d 50% (50% weight loss at temperature of degradation), the temperature of degradation of PU–imide copolymers increased with increasing hard segment content. Mechanical properties revealed that the modulus and tensile strength of PU–imide copolymers surpassed those of PU. Wide angle X-ray diffraction patterns demonstrated that PU–imide copolymers are crystallizable. © 1999 Society of Chemical Industry     

Polyurethane acrylate/epoxy–amine acrylate hybrid polymer networks

New classes of hybrid polymer networks (HPNs), having variable polyurethane acrylate (PUA) and epoxy–amine acrylate (EAA) compositions, were prepared using initially miscible systems in methyl methacrylate (MMA). The initial systems were based on PUA prepolymer and EAA monomer solutions in MMA. HPNs were a result of epoxy–amine and radical polymerization competition. Phase separation occurred during the course of HPN formation. Mechanical dynamic analysis of the prepared HPNs showed good affinity between the PUA and PMMA phases and lower affinity between the EAA and PMMA phases. Mechanical property evolution and transmission electronic microscopy showed that, for all the composition ranges used in this study (PUA/EAA/PMMA 15/45/40–45/15/40 wt %), the PUA‐rich phase was the continuous phase. EAA‐rich phases, 20–50 nm, in the PUA‐rich matrix were obtained for HPNs containing up to 30 wt % EAA. For higher EAA concentration (45 wt %), 2 μm EAA‐rich phases were obtained in the PUA‐rich matrix. A substructure was also observed in each phase. PUA/EAA copolymers were prepared and used successfully for the compatibilization of the different phases of the HPNs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2711–2717, 2000     

Epoxy–imide resins from N‐(4‐ and 3‐carboxyphenyl)trimellitimides. I. Adhesive and thermal properties

Epoxy–imide resins were obtained by curing Araldite GY 250 (diglycidyl ether of bisphenol‐A and epichlorohydrin; difunctional) and Araldite EPN 1138 (Novolac–epoxy resin; polyfunctional) with N‐(4‐ and 3‐carboxyphenyl)trimellitimides derived from 4‐ and 3‐aminobenzoic acids and trimellitic anhydride. The adhesive lap shear strength of epoxy–imide systems at room temperature and at 100, 125, and 150°C was determined on stainless‐steel substrates. Araldite GY 250‐based systems give a room‐temperature adhesive lap shear strength of about 23 MPa and 49–56% of the room‐temperature adhesive strength is retained at 150°C. Araldite EPN 1138‐based systems give a room‐temperature adhesive lap shear strength of 16–19 MPa and 100% retention of room‐temperature adhesive strength is observed at 150°C. Glass transition temperatures of the Araldite GY 250‐based systems are in the range of 132–139°C and those of the Araldite EPN 1138‐based systems are in the range of 158–170°C. All these systems are thermally stable up to 360°C. The char residues of Araldite GY 250‐ and Araldite EPN 1138‐based systems are in the range of 22–26% and 41–42% at 900°C, respectively. Araldite EPN 1138‐based systems show a higher retention of adhesive strength at 150°C and have higher thermal stability and T_g when compared to Araldite GY 250‐based systems. This has been attributed to the high crosslinking possible with Araldite EPN 1138‐based systems arising due to the polyfunctional nature of Araldite EPN 1138. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1729–1736, 2000     

Study on synthesis and thermal properties of polyurethane–imide copolymers with multiple hard segments

Different multiple hard segment polyurethane–imide copolymers (MHPUI) were synthesized and characterized. FTIR spectroscopy confirmed the characteristic absorption of the MHPUI copolymer. The difference in the imide group FTIR absorption bands in different MH segment PUI copolymers was found in this study and was explained by the different MH segment types, hard segment contents, and hard segment rigidity with different interactions of the molecular chains. The hard segment interaction in MHPUI with an increase of the structure rigidity of the short hard segments is strengthening. The DSC analysis revealed that the glass‐transition temperature of the soft segment of PUI rose in value from ?42 to ?3.4°C with the introduction of MH and different MH segments. The DSC results suggest that the soft segment is more compatible with the hard segment rigidity increase. The TGA results showed the hard segment structure symmetry has a more important role in the MHPUI thermal stability. Every sample containing symmetrical structure short hard groups (4,4′‐diphenylmethane diisocyanate or 4,4′‐diaminodiphenylmethane) is more thermally stable than that with worse symmetry structure groups (2,4‐toluene diisocyanate or 3,3′‐dichloro‐4,4′‐diamino‐diphenylmethane). The three‐step mechanism of PUI thermal degradation was further verified by the TGA study. The thermally unstable group was confirmed as urethane or a urea–urethane segment. The TGA results showed that MHPUI copolymers with higher separation of the soft–hard phase have higher thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2206–2215, 2002     

Synthesis,properties and pyrolysis of siloxane‐ and imide‐modified epoxy resin cured with siloxane‐containing dianhydride

Hydrosilylation of nadic anhydride with tetramethyl disiloxane yielded 5,5′‐(1,1,3,3‐tetramethyl disiloxane‐1,3‐diyl)‐bis‐norborane‐2,3‐dicarboxylic anhydride (I), which further reacted with 4‐aminophenol to give N,N′‐bis(4‐hydroxyphenyl)‐5,5′‐bis‐(1,1,3,3‐tetramethyl disiloxane‐1,3‐diyl)‐bis‐norborane‐2,3‐dicarboximide (II). Epoxidation of II with excess epichlorohydrin formed a siloxane‐ and imide‐modified epoxy oligomer (ie diglycidyl ether of N,N′‐bis(4‐hydroxyphenyl)‐5,5′‐bis(1,1,3,3‐tetramethyl disiloxane‐1,3‐diyl)‐bis‐norborane‐2,3‐dicarboximide) (III). Equivalent ratios of III/I of 1/1 and 1/0.8 were prepared and cured to produce crosslinked materials. Thermal mechanical and dynamic mechanical properties were investigated by TMA and DMA, respectively. It was noted that each of these two materials showed a glass transition temperature (T_g) higher than 160 °C with moderate moduli. The thermal degradation kinetics was studied with dynamic thermogravimetric analysis (TGA) and the estimated apparent activation energies were 111.4 kJ mol^?1 (in N₂), 117.1 kJ mol^?1 (in air) for III/I = 1/0.8, and 149.2 kJ mol^?1 (in N₂), 147.6 kJ mol^?1 (in air) for III/I = 1/1. The white flaky residue of the TGA char was confirmed to be silicon dioxide, which formed a barrier at the surface of the polymer matrix and, in part, accounted for the unique heat resistance of this material. Copyright © 2005 Society of Chemical Industry     

Curing of epoxy–urethane copolymers in a heated mold: Effect of the curing conditions on the phase‐separation process

The curing process of an epoxy–urethane copolymer in a heated mold was studied. The epoxy resin (DGEBA, Araldyt GY9527; Ciba Geigy), was coreacted with a urethane prepolymer (PU, Desmocap 12; Bayer) through an amine that acted as crosslinking agent (mixture of cycloaliphatic amines; Distraltec). The study focused on the effect of the curing condition and PU concentration on time–temperature profiles measured in the mold and the consequent final morphologies obtained. As the PU concentration increases, the maximum temperature reached in the mold decreases as a result of the dilution effect of the elastomer on reaction heat, whereas the T_g of the piece also decreases. Phase separation is a function of conversion and temperature reached in the curing part and was analyzed using experimental data and a mathematical model that predicts temperature and conversion throughout the thickness of the mold. Scanning electron microscopy and atomic force microscopy were used to determine the characteristics of the dispersed phase for the different formulations and conditions of curing. It was shown that the size of the dispersed phase increased with the initial PU concentration, whereas there were practically no differences in the separated phase as a function of position or temperature of curing (in the range of 70 to 100°C studied). The superposition of the phase diagrams with the conversion–temperature trajectories during cure provided an explanation of the morphologies generated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 889–900, 2001     

Synthesis of hyperbranched aromatic polyamide–imide and its grafting onto multiwalled carbon nanotubes

A flexible hyperbranched aromatic polyamide–imide (PAI) having an amine group in the center and carboxyl groups in the ends was synthesized from a AB₂ type of monomer of 2‐(6‐aminohexylcarbomoyl) terephthalic acid that was prepared from trimellitic anhydride and 1,6‐diaminohexane. Fourier transformed infrared spectra (FTIR), NMR, and ES‐MS were used to characterize the structure of the monomer and the synthesized hyperbranched polymer. Then the hyperbranched PAI was grafted onto the multiwalled carbon nanotubes (MWNTs) that was first treated by acid and changed into MWNT‐COCl by SOCl₂ in a tetrahydrofuran solution. By observation with transmission electron microscopy and characterization with FTIR and thermal gravity of analysis, the functionalized MWNTs were terminally enclosed with polymer; it was believed that the MWNTs were linked with a big carboxylic claw at the end and the adsorption ability of the MWNTs to NH₂‐substrate was enhanced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis and properties of poly(ether imide)s derived from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and aromatic ether–diamines

A series of poly(ether imide)s (PEIs) with light colors and good mechanical properties were synthesized from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and various aromatic ether–diamines via a conventional two‐step polymerization technique that included ring‐opening polyaddition at room temperature to poly(amic acid)s (PAAs) followed by thermal imidization. The precursor PAAs had inherent viscosities ranging from 0.71 to 1.19 dL/g and were solution‐cast and thermally cyclodehydrated to flexible and tough PEI films. All of the PEI films were essentially colorless, with ultraviolet–visible absorption cutoff wavelengths between 377 and 385 nm and yellowness index values ranging from 10.5 to 19.9. These PEIs showed high thermal stabilities with glass‐transition temperatures of 206–262°C and decomposition temperatures (at 10% weight loss) higher than 478°C. They also showed low dielectric constants of 3.39–3.72 (at 1 MHz) and low water absorptions below 0.85 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

含芳醚芴二胺/环氧树脂固化反应动力学及性能研究

以9,9-双[4-4-氨基苯氧基苯基]芴(BAOFL)作为固化剂,采用非等温DSC技术,研究了BAOFL/环氧树脂(E-51、TDE-85和芴基环氧树脂)体系的固化反应动力学,利用动态热机械分析仪(DMA)和热重分析仪(TGA)测试了固化树脂的力学性能和热稳定性。结果表明,固化反应活化能与环氧树脂和固化剂的结构密切相关,芳醚的引入提高了氨基与环氧基的反应性,固化树脂呈现出优良的热性能和力学性能,其玻璃化转变温度(T)达到206~248℃,贮能模量为2.54~2.94 GPa,初始热分解温度312~375℃,700℃g时的残炭率达到15.2%~31.7%。()     

Synthesis and characterization of novel diimide–dinaphthols and resulting poly(urethane–imide)s

Novel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical properties, such as solubility, solution viscosity, thermal stability, and thermal behaviour were studied. The polymers obtained showed more thermal stability than typical polyurethanes because of the presence of the imide groups. Copyright © 2003 Society of Chemical Industry     

Synthesis and properties of phosphorus and nitrogen containing intumescent flame-retardant curing agent for epoxy resin

A kind of intumescent ?ame-retardant curing agent (PCDSPB) was synthesised by using pentaerythritol, phosphorus oxycholoride, cyclohexane-1,3-diyldimethanamine (1,3- BAC) as raw materials and the structure was characterised by FTIR and MS. The composite materials were investigated by using TG, TG-FTIR, LOI, UL-94, SEM, and CCT. The results show that the ?lling of PCDSPB can improve the ?ame resistance of EP composites. When the phosphorus content of the composite system was 1.74 wt-%, the initial weight loss temperature was 299°C and the char yield was 26.3% at 600°C. Tensile strength was 35.4 MPa, impact strength was4.3 kJ m?2, LOI was 27.9, and the UL94 passed V-0 level. In the CCT, the peak heat release rate reduced to 276.0 kW m?2(EP-2) from 622.8 kW m?2 (EP-0), the total heat release decreased from 121.8 MJ m?2 (EP-0) to 89.5 MJ m?2 (EP-2). Therefore, the PCDSPB is a good intumescent ?ame-retardant curing agent for EP.     

Preparation and characterization of epoxy resin modified with alkoxysilane‐ functionalized poly(urethane‐imide) by the sol–gel process

The sol–gel process has been frequently employed for preparation of high performance silica/polymer composites. In this paper, novel sol–gel precursor triethoxysilane‐terminated poly(urethane‐imide) (PUI‐Si), combining the advantages of polyurethane (PU) and polyimide, was synthesized and characterized. Then PUI‐Si was incorporated into the epoxy resin matrix to prepare a series of EP/PUI‐Si organic‐inorganic hybrids through an in situ sol–gel process and crosslinking reactions. The thermal stability of EP/PUI‐Si hybrids was evaluated by thermogravimetric analysis and the results show that the PUI‐Si could significantly improve the thermal properties of epoxy resin. The initial decomposition temperature of composites with 50 wt% PUI‐Si reached 347.1 °C, 157.3 °C higher than that of neat epoxy resin. Furthermore, the tensile strength and breaking elongation can also be clearly improved by adding a suitable amount of PUI‐Si. Similarly, the water contact angle increased to 97.4° with 70 wt% PUI‐Si, showing a hydrophobic surface. The morphology was investigated by transmission electron microscopy and the results reveal that the silica particles are smaller than 20 nm and have a strong interaction with the epoxy resin matrix, resulting in the above‐mentioned high performance properties. Copyright © 2011 Society of Chemical Industry