Methylhexahydrophthalic Anhydride Research Articles

Nanoscale Bubble Valves on MWCNT Membranes for Chemical Energy Storage

Nanoscale Bubble Valves on MWCNT Membranes for Chemical Energy Storage

Positron annihilation lifetime spectroscopy study on the structural relaxation of phenylmethylsiloxane-modified epoxy hybrids at different aging temperatures

The cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 produced using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150 °C and 55 °C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150 °C and 55 °C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150 °C; By contrast, there were two separate relaxation times of 37.4 h (ζ1) and 753.6 h (ζ2) at 55 °C. The ζ1 of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ2 can be attributed to the network relaxation of DGEBA at 55 °C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours.

Synthesis of a liquid zirconium hybrid resin and the ability of the resin to accelerate the curing of a transparent silicone-modified cycloaliphatic epoxy nanocomposite

A liquid zirconium hybrid resin (Zr–QR) was synthesized through sol-gel reactions of zirconium butoxide with silanol-terminated polydimethylsiloxane (DMS-S12) and γ-glycidoxypropyltrimethoxysilane (Z-6040). The sol-gel reactions were monitored using Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy. The Zr–QR morphology was investigated using field emission transmission electron microscopy. The Zr–QR had a well-ordered morphology and the dimensions were less than 5 nm. These properties were achieved because DMS-S12 was used to separate the zirconium clusters and Z-6040 was used to stabilize the Zr–QR. The acceleration of the curing reaction between silicone-modified cycloaliphatic epoxy (SEP) and methylhexahydrophthalic anhydride (MHHPA) caused by the Zr–QR was investigated. Differential scanning calorimetry and FTIR spectroscopy investigations showed that the Zr–QR first reacted with MHHPA, producing chelating ligands and carboxylic acid. Unlike in the conventional method (adding acetic acid to cause non-reactive chelating ligands to form), the carboxylic acid produced effectively accelerated the curing reaction between the SEP and MHHPA. The chelating ligand produced from the Zr–QR and MHHPA suppressed the gelation of the Zr–QR itself during the nanocomposite (SEP–Zr–QR) curing process. The cured SEP–Zr–QR nanocomposite exhibited excellent optical transmittance at visible wavelengths.© 2015 Society of Chemical Industry

Effect of urethane functionality and number of epoxide groups on cure and mechanical behaviors of epoxy resins

We report the synthesis of the novel bi- and tetrafunctional epoxy resins, 2-ECI and 4-ECI, containing urethane functionality. Their chemical structures were characterized by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The effects of urethane functionality and the number of epoxide groups on the curing behavior and physical and mechanical properties of the epoxy resins were investigated. Compared to 4-ECI, 2-ECI was more reactive with the curing agent methyl hexahydrophthalic anhydride. However, the shear strength and critical stress intensity factor values of the cured 4-ECI resin were significantly higher than those of the cured bisphenol-A diglycidylether and 2-ECI resin, which was attributed to the synergistic effects of urethane functionality and high cross-linking density in the cured 4-ECI resin.

Structures and properties of nanocomposites based on a cured cycloaliphatic epoxy resin

The effect of nanoparticles on glass-transition temperature Tg and the elastic modulus of a cycloaliphatic epoxy resin cured with methylhexahydrophthalic anhydride is theoretically analyzed. The analysis was performed with allowance for the following factors: the chemical structure of the polymer, the chemical structures of the nanoparticles and their surfaces if they are modified, the concentrations and shapes of nanoparticles (spherical, plate, cylindrical), the concentration of functional groups on the surfaces of nanoparticles, the energy of intermolecular interaction between a polymer and a nanoparticle, and the possibility of chemical interaction between a polymer and the surfaces of nanoparticles. The most pronounced effect on Tg is exerted by cylindical nanotubes, whose surfaces are modified with OH groups, which give rise to hydrogen bonding. The least effect is exerted by spherical nanoparticles. After the introduction of SiO2 nanoparticles, the elastic moduli of nanocomposites increase by a factor of 1.15 at an amount of nanoparticles up to 20%.

Preparation and Properties of Rectorite/Epoxy Nanocomposites

The Org-rectorite, which was used as a filler in the Rectorite/Epoxy nanocomposites, was prepared by the intercalation and exfoliation of rectorite with dodecyl-bis (2-hydroxyethyl)-methylazanium chloride as the organic cation exchange agent. The two curing agents methyl hexahydrophthalic anhydride (MHHPA) and m-phenylenediamine were employed at working temperature ranging from 70 °C to 190 °C. The samples were characterized by Fourier Transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) analysis. The results show that the d001 (55.9 Å) of Rectorite/Epoxy composites cured with MHHPA at 70 °C was larger than the Org-rectorite (28.7 Å), and the Org-rectorite was exfoliated at 90 °C working temperature. While the d001 of Rectorite/Epoxy composites cured with m-phenylenediamine at 70 °C and 90 °C were 40.9 Å and 42.1 Å , and were exfoliated at 140 °C. The apparent activation energy (Ea) of Rectorite/Epoxy composites cured with MHHPA and m-phenylenediamine were obtained to be 74.85 and 59.15 KJ/mol, respectively. The higher apparent activation energy (Ea) of MHHPA systems may be responsible for the lower exfoliation temperature.

Synthesis and characterization of high refractive epoxy prepolymers with different molecular structures

Three kinds of epoxy prepolymers with high refractive index, diglycidyl ether of thiodibenzenethiol (DGETDBT), diglycidyl ether of thiobis-phenol (DGETP), and diglycidyl ether of oxydiphenol, were synthesized via a two-step method, and the relationship between the chemical structure and refractive index of epoxy prepolymer was discussed. Their chemical structures were characterized using Fourier transform infrared (FTIR) spectrometer and proton nuclear magnetic resonance spectrometer. The curing behavior of all the epoxy prepolymers cured with methylhexahydrophthalic anhydride (MHHPA) was studied using differential scanning calorimetry and was compared with that of diglycidyl ether of bisphenol A (DGEBA). Thermal and optical properties of these cured epoxy resins were investigated using thermogravimetric analyses, ultaviolet–visible scanning spectrophotometer, and Abbe refractometer, respectively. The results showed that three kinds of epoxy prepolymers had the similar thermal property and curing behavior. The sulfur atoms in DGETDBT and DGETP had contributed to an obvious increase in their refractive indexes, while the methyl group in DGEBA cut down its refractive index. The DGETDBT has the biggest refractive index (1.665), followed by the DGETP with 1.612. But the high cost and the lower thermal decomposition temperature of cured DGETDBT/MHHPA resin will limit its application. The refractive index of cured DGETP/MHHPA resin, with preferable thermal stability and acceptable price, is 1.595, which is higher than that of DGEBA/MHHPA resin (1.568). Therefore, DGETP resin can be expected to be a kind of the more effective encapsulant to light-emitting diode.

Synthesis and properties of phosphorus-containing bio-based epoxy resin from itaconic acid

A phosphorus-containing bio-based epoxy resin (EADI) was synthesized from itaconic acid (IA) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO). As a matrix, its cured epoxy network with methyl hexahydrophthalic anhydride (MHHPA) as the curing agent showed comparable glass-transition temperature and mechanical properties to diglycidyl ether in a bisphenol A (DGEBA) system as well as good flame retardancy with UL94 V-0 grade during a vertical burning test. As a reactive flame retardant, its flame-resistant effect on DGEBA/MHHPA system as well as its influence on the curing behavior and the thermal and mechanical properties of the modified epoxy resin were investigated. Results showed that after the introduction of EADI, not only were the flame retardancy determined by vertical burning test, LOI measurement, and thermogravimetric analysis significantly improved, but also the curing reactivity, glass transition temperature ( T g), initial degradation temperature for 5% weight loss ( T d(5%)), and flexural modulus of the cured system improved as well. EADI has great potential to be used as a green flame retardant in epoxy resin systems.

Study on Electrical Properties and Morphology Behaviors of Epoxy Nanocomposites with Octa(3-aminopropyl)Polyhedral Oligomeric Silsesquioxane

In this work, octa(3-aminopropyl)polyhedral oligomeric silsesquioxane (Oap-POSS) [(NH2CH2CH2CH2)8Si8O12] was synthesized through hydrolytic condensation of (3-aminopropyl)triethoxysilane, and incorporated into epoxy resin (EP) cured with methyl hexahydrophthalic anhydride (MHHPA) to offer a series of novel POSS/EP nanocomposites. The microstructure, thermal stabilities, electric insulation and dielectric behaviors of the epoxy nanocomposites were studied. The results showed that the thermal stability and dielectric property of the POSS/EP increases with the incorporation of Oap-POSS into EP.

Synthesis and Properties of a Bio‐Based Epoxy Resin with High Epoxy Value and Low Viscosity

A bio-based epoxy resin (denoted TEIA) with high epoxy value (1.16) and low viscosity (0.92 Pa s, 258C) was synthesized from itaconic acid and its chemical structure was confirmed by 1H NMR and 13C NMR spectroscopy. Its curing reaction with poly(propylene glycol) bis(2-aminopropyl ether) (D230) and methyl hexahydrophthalic anhydride (MHHPA) was investigated. For comparison, the commonly used diglycidyl ether of bisphenol A (DGEBA) was also cured with the same curing agents. The results demonstrated that TEIA showed higher curing reactivity towards D230/MHHPA and lower viscosity compared with DGEBA, resulting in the better processability. Owing to its high epoxy value and unique structure, comparable or better glass transition temperature as well as mechanical properties could be obtained for the TEIA-based network relative to the DGEBA-based network. The results indicated that itaconic acid is a promising renewable feedstock for the synthesis of bio-based epoxy resin with high performance.

Biodegradability of Epoxidized Soybean Oil Based Thermosets in Compost Soil Environment

In this study, bio-thermoset from epoxidized soybean oil (ESO) was prepared in the presence of methylhexahydrophthalic anhydride curing agent and 2-ethyl-4-methylimidazole catalyst. The crosslink densities of the synthesized ESO are ranged from 0.109 × 10−3 to 0.308 × 10−3 mol/cm3. The ESO bio-thermosets were exposed to the soil-burial test for 8 months. Weight change and morphology of the degraded ESO specimens were assessed. It was found that the weight loss of ESO was governed by the materials compositions, crosslink density and the soil-burial exposure time. The 3 mm thickness ESO bio-thermosets with crosslink density of 0.109 × 10−3 mol/cm3 had fully biodegraded after soil-burial for 6 months. In addition, 16S rDNA sequencing was carried out to identify the soil microorganisms. It was suggested that Comamonas sp., Bacillus sp., Streptomyces sp. and Acinetobacter sp. are the possible soil microbes that degrade the ESO bio-thermosets in the compost soil environment.

Synthesis and property of epoxy prepolymer and curing agent with high refractive index

An epoxy prepolymer with high refractive index, diglycidyl ether of thiodiphenol (DGETP), was synthesized by 4,4′-thiodiphenol and epichlorohydrin via a two-step method. The curing agent o-benzenedimethanethiol (OBDMT) was synthesized by thiourea method. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance were employed to characterize the structures of these resins. The cured product of DGETP and OBDMT was analyzed by differential scanning calorimetry, ultraviolet–visible spectrometer, and Abbe refractometer and compared with the property of traditional curing agent of methyl hexahydrophthalic anhydride (MHHPA) and ordinary bisphenol A diglycidyl ether epoxy prepolymer cured products. The lower curing temperature and glass transition temperature of DGETP than those of MHHPA can be mainly attributed to the strong rotation capability of thioether bond. The zero light transmittance region of DGETP/OBDMT curing adhesive (200–380 nm) was broader than that of the other three. The refractive index of DGETP/OBDMT was up to 1.654.

Synthesis and properties of methyl hexahydrophthalic anhydride‐cured fluorinated epoxy resin 2,2‐bisphenol hexafluoropropane diglycidyl ether

ABSTRACTThe fluorinated epoxy resin, 2,2‐bisphenol hexafluoropropane diglycidyl ether (DGEBHF) was synthesized through a two‐step procedure, and the chemical structure was confirmed by 1H nuclear magnetic resonance (NMR), 13C NMR, and Fourier transform infrared (FTIR) spectra. Moreover, DGEBHF was thermally cured with methyl hexahydrophthalic anhydride (MHHPA). The results clearly indicated that the cured DGEBHF/MHHPA exhibited higher glass transition temperature (Tg 147°C) and thermal decomposition temperature at 5% weight loss (T5 372°C) than those (Tg 131.2°C; T5 362°C) of diglycidyl ether of bisphenol A (DGEBA)/MHHPA. In addition, the incorporation of bis‐trifluoromethyl groups led to enhanced dielectric properties with lower dielectric constant (Dk 2.93) of DGEBHF/MHHPA compared with cured DGEBA resins (Dk 3.25). The cured fluorinated epoxy resin also gave lower water absorption measured in two methods relative to its nonfluorinated counterparts. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2801–2808, 2013

Interpenetrating polymer network structured thermosets prepared from epoxidized soybean oil/diglycidyl ether of bisphenol A

AbstractEpoxidized soybean oil (ESO)/diglycidyl ether of bisphenol A (DGEBA) in various blend ratios (i.e. 100/0, 90/10, 80/20, 70/30, 60/40, 50/50) was thermally cured using methylhexahydrophthalic anhydride in the presence of 2‐ethyl‐4‐methylimidazole catalyst. The tensile properties and fracture toughness of the ESO/DGEBA thermoset blends were determined. Thermal properties of the blends were characterized using dynamic mechanical analysis, differential scanning calorimetry and thermogravimetric analysis. Blending of ESO and DGEBA gave synergistic effects on the modulus, strength, glass transition temperature and thermal stability. However, the fracture toughness and elongation at break of ESO/DGEBA blends are lower than those of ESO, as expected. The enhancement in certain mechanical and thermal properties of ESO/DGEBA can be associated with the crosslink density, gel content and possible interpenetrating network of the resulting thermoset blends. © 2013 Society of Chemical Industry

Bio-based epoxy resin from itaconic acid and its thermosets cured with anhydride and comonomers

A novel itaconic acid (IA) based epoxy resin with curable double bonds (EIA) was synthesized by the esterification reaction between IA and epichlorohydrin (ECH). Its chemical structure was confirmed in detail by FT-IR, 1H-NMR and ESI-ION TRAP MS before being cured by methyl hexahydrophthalic anhydride (MHHPA). In order to manipulate the properties of the cured resin, divinyl benzene (DVB) and acrylated epoxidized soybean oil (AESO) were employed here to act as comonomers. The results demonstrated that EIA showed a higher epoxy value of 0.625 and higher curing reactivity toward MHHPA compared with the commonly used diglycidyl ether of bisphenol A (DGEBA). The glass transition temperature, tensile strength, flexural strength and modulus of the cured EIA without comonomers were 130.4 °C, 87.5 MPa, 152.4 MPa and 3400 MPa, respectively, which were comparable or better than those of DGEBA cured by the same curing agent. After being copolymerized with DVB or AESO, the properties of the cured EIA could be regulated further. The results indicated that EIA has great potential to replace the petroleum-based thermosetting resin, such as DGEBA.

Thermal behavior of epoxy blends for light emitting diode encapsulation

AbstractEpoxy encapsulant with high glass transition temperature (Tg) is required to ensure light emitting diode (LED) functions properly during its service life. Epoxy blends (cycloaliphatic epoxy, diglycidyl ethers of bisphenol-A and novolac resin) were thermally cured using methylhexahydrophthalic anhydride. Effects of the three types epoxy resins on the Tg of the ternary blends were examined. The Tg was mainly controlled by the concentration of cycloaliphatic epoxy. Optimization with constraint was conducted to produce epoxy blends formulation with optimum Tg. It was found that linear mixture model can fit well the experimental Tgof the epoxy ternary blends.

Relationships of cure kinetics and processing for epoxidized soybean oil bio-thermoset

Epoxidized soybean oil (ESO) resin was thermally cured using methylhexahydrophthalic anhydride (MHHPA) curing agent, in the presence of 2-ethyl-4-methylimidazole (EMI) catalyst at different temperatures (i.e., 130, 135, 140, 145 and 150°C). Curing kinetics of the ESO/MHHPA systems was studied using Fourier Transform Infrared Spectroscopy (FTIR). The EMI-catalyzed ESO/MHHPA system showed autocatalytic behavior in the isothermal curing reaction. The kinetic parameters; reaction rate constants (k1 and k2) and reaction orders (m and n) of the ESO/MHHPA systems have been determined based on Kamal's autocatalytic model. EMI catalyst content and curing temperature showed significant effect on k1, k2, m and n. The overall reaction order (m+n) of the EMI-catalyzed ESO/MHHPA systems was about 1.5–3.0. The apparent activation energies (Ea1 and Ea2) were determined using the Arrhenius kinetic equation. As expected, the Ea1 and Ea2 had decreased with increasing EMI catalyst content. The critical conversion, αc was found to be in the range of 0.6–0.8. Curing reaction of ESO/MHHPA system as a function of EMI catalyst content can be well-described by introducing the diffusion factor, f(α) into Kamal's autocatalytic model.

Role of accelerator in curing of epoxy-anhydride pressure impregnant

In the present paper, Differential Scanning Calorimetry (DSC) has been applied to bring out the role of zinc naphthenate accelerator in the curing of epoxy-anhydride pressure impregnant used for impregnation of electrical machines. Effect of concentration of zinc naphthenate on curing behavior of bisphenol-A epoxy resin and methylhexahydrophthalic anhydride hardener has been studied by obtaining dynamic DSC thermograms for uncatalysed, and catalysed system with various concentration of zinc naphthenate. The investigations reveal that the un-catalyzed purified epoxyanhydride mix exhibits an endothermic peak at temperature around 260 °C in place of cure exothermic peak in the DSC curve. The analysis of DSC and TGA data of individual resin, hardener and their mix indicate that the endothermic peak is attributed to the evaporation of resin and hardener implying that the hardener does not react with resin in absence of accelerator. The addition of zinc naphthenate accelerator at concentration of 1 pph (parts of zinc naphthenate per hundred parts of resin- hardener mix) causes two exothermic peaks in the DSC thermogram. The position and area under these peaks vary with the accelerator content resulting in the variation in the processing parameters and the performance properties of the cured material. The first peak from esterification reaction appears between 90 and 200 °C and second peak from etherification reaction appears in the temperature range of 180 to 330 °C. The area under the first exothermic peak appearing at low temperature increases with increase of accelerator content and predominates at concentration of ≥ 1.5 pph. The area under the second exothermic peak appearing at high temperature increases with the decrease of accelerator content and predominates at concentration of ≤ 0.5 pph. The accelerator concentration of 2 pph provides maximum reactivity.

Synthesis and curing of liquid crystalline epoxy resin based on asymmetric mesogen

A novel liquid crystalline epoxy resin (LCER) derived from asymmetric mesogen unit was synthesized. Its structure and liquid crystalline behavior were characterized by hydrogen nuclear magnetic resonance (H-NMR), differential scanning calorimetry (DSC), polarized optical microscopy (POM). The results indicated that the LCER converted to a nematic phase at 85°C during heating and finally became isotropic at 145°C. The curing behavior and phase behavior of the LCER with 4,4′-diaminodiphenyl methane and methyl hexahydrophthalic anhydride were also studied by DSC and POM, respectively. Their apparent activation energy (Ea) was evaluated according to the Ozawa's isoconversional method. The results suggested that autocatalytic reaction had occurred in these two systems. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effects of 2-ethyl-4-methylimidazole and tetraethylammonium bromide on the fracture properties of epoxidized soybean oil based thermoset

In this paper, we aim to report the effects of catalyst (types and concentrations) on the fracture mechanics of epoxidized soybean oil (ESO) based thermosets. ESO resin was thermally cured using methylhexahydrophthalic anhydride curing agent in the presence of two types of catalysts, i.e., tetraethylammonium bromide and 2-ethyl-4-methylimidazole (EMI). The loading of the catalysts varied from 0.3 to 0.8 phr. The fracture behaviour of ESO thermoset was examined on the basis of the principle of linear elastic fracture mechanics (LEFM) and essential work of fracture (EWF). LEFM measurements were performed using single-edge notched tensile and double-edge notched tensile (DENT) tests, while, EWF measurements were carried out using DENT tests. The fracture morphologies of the ESO thermosets were characterized via field emission scanning electron microscopy. It was determined that the plane-strain fracture toughness (KIC), the specific EWF (we), and the specific plastic fracture work (βwp) of ESO thermosets were significantly influenced by the types and loading of catalysts. In addition, the fracture toughness properties were associated with the crosslink density of the ESO thermosets. In addition, it was found that the brittle–ductile transition of EMI-catalyzed ESO thermosets can be assessed by the combination of LEFM and EWF in the fracture toughness measurement.