Diglycidyl Ether Of bisphenol-A Epoxy Resin Research Articles

Studies on thermal, mechanical and morphological properties of organoclay filled azomethine modified epoxy nanocomposites

Inter cross-linked networks of organoclay-filled, azomethine-modified epoxy nanocomposites have been developed. Two types of azomethine epoxies (AE1 and AE2) incorporated into diglycidyl ether of bisphenol A (DGEBA) epoxy resin with varying percentages (5, 10 and 15%) were cured with diamine diphenyl methane (DDM). The azomethine epoxies were synthesized and characterized by Fourier transform infrared and 1H-NMR spectroscopy. The incorporation of azomethine epoxies into DGEBA epoxy resin improved both thermal and mechanical properties to an appreciable extent. The introduction of organoclay into DGEBA epoxy resin exhibited almost similar characteristics to that of the azomethine-modified DGEBA epoxy resin. Both azomethine epoxy and organoclay have been incorporated into DGEBA epoxy resin in order to improve the thermal and mechanical properties in comparing other modified epoxies. The glass transition temperature and thermal degradation temperature of azomethine-modified epoxies, organoclay-filled epoxy and organoclay-filled azomethine-modified DGEBA epoxies were determined by using differential scanning calorimeter and thermogravimetric analysis. The mechanical properties, namely the tensile strength, flexural strength and impact strength of the resultant nanocomposites were studied as per ASTM standards. X-ray diffraction studies of the cured nanocomposites indicate that the organophillic montmorillonite clay was exfoliated into the cured product. The homogeneous morphology of azomethine-modified DGEBA epoxy and organoclay-filled azomethine-modified epoxy were ascertained by scanning electron microscopy.

Novel Interacting Blends of Unsaturated Polyester-s-Triazine and Epoxy Resin

2-(4-ethyl-1-piperazinylo)-4,6-bismaleatedethylamino-1,3,5-triazine (EBT) was prepared by the reaction of 2-(4-ethyl-1-piperazinylo)-4,6-bishydroxyethylamino-1,3,5-triazine and maleic anhydride. The EBT derivative was characterized by elemental analysis, acid value and spectral studies. EBT was then polycondensed respectively with three commercial epoxy resins, namely diglycidyl ether of bisphenol-A (DGEBA), diglycidyl ether of bisphenol-F (DGEBF) and diglycidyl ether of bisphenol-C (DGEBC). The resultant polymers are designated as unsaturated polyester-s-triazine (UPETs) and were characterized by elemental analysis, spectral study, molecular weight determination, differential scanning calorimeter (DSC)and thermogravimetry. The interacting blends of UPETs with DGEBA epoxy resin was made at stoichiometric ratio. The blending of these systems was monitored on a differential scanning calorimeter (DSC), and based on DSC data the glass-reinforced composites (GRCs) were prepared and characterized by physical and mechanical properties.

Intermolecular force and thermal properties of the sulfonyl epoxy blends cured with DGEBA epoxy

AbstractThe sulfonyl epoxy monomer (SEP) was synthesized and further to blend with the diglycidyl ether of bisphenol A (DGEBA). The glass transition temperature (Tg) of the SEP/DGEBA blended materials increased from 103.7 to 163.8°C. The cross‐linking density and polymer chain self‐association intra‐molecular action affected more than that the polymer–polymer intermolecular action (hydrogen bonding) in the SEP blended with the DGEBA materials. The excess stabilization energy in the overall stabilization was only 0.00145% (14.5 ppm), which indicated that the polymer‐polymer intermolecular action was weak. The thermal degradation of the SEP segments could form various sulfate derivatives at lower temperature and analyzed by the TGA/GC/Mass. The sulfate derivatives could generate the thermal stable chars, which provided the “shielding effect” and antioxidation property. Additionally, these chars could also improve the protective effect and inhibit the thermal‐oxidation decomposition under the air atmosphere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Influence of phenoxy modifier on mechanical, electrical and morphological properties of epoxy/DDS system

The blends of diglycidyl ether of bisphenol-A (DGEBA) and poly (hydroxyl ether of bisphenol-A) or phenoxy were synthesized by melt blending at 120 °C. These blends were cured by an aromatic amine hardener, 4,4′- diaminodiphenyl sulphone (DDS). The experiments were performed to study the different amount of phenoxy (10 to 40 parts per hundred resins) on mechanical and electrical properties of the DGEBA/phenoxy blends, such as tensile properties, flexural properties, impact strength, Rockwell hardness, and volume resistivity. The oxirane group of DGEBA epoxy resin reacts with hydroxyl group of phenoxy which provides good toughness to the epoxy resin. The tensile strength, tensile modulus, flexural strength, flexural modulus, heat deflection temperature and volume resistivity of DGEBA/phenoxy blends decreased with increasing the amount of phenoxy from 10 to 40 parts per hundred resins (phr). The opposite trend was observed in impact strength and Rockwell hardness of all DGEBA/phenoxy blends which were increased with increasing the phenoxy content from 10 to 20 phr, but then decreased upto 40 phr. The SEM studies revealed that the DGEBA/phenoxy blends show a multiphase system with an increase in the phenoxy content from 10 to 40 phr. due to inconvenience of mixing of two phases.

Preparation, characterization and curing properties of epoxy-terminated poly(alkyl-phenylene oxide)s

A series of dihydroxyl telechelic poly(alkyl-phenylene oxide)s ( 1) have been synthesized by oxidative polymerization of alkylphenols with various aromatic diols using manganese or copper amine catalysts. The novel telechelic derivatives ( 1) were epoxidized with epichlorohydrin yielding a series of new epoxidized poly(alkyl-phenylene oxide)s (EPPO, 2) and the structures, properties were studied by nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and gel permeation chromatography (GPC). The 1:1 blends of diglycidyl ether of bisphenol-A (DGEBA) with EPPO resins were cured with three curing agents and the effects of chemical structure change on thermal property of the curing matrixes were discussed. Incorporation of EPPOs to DGEBA epoxy system resulted in a significant increase in its glass transition temperature ( T g), thermal stability and flame resistance. The T g values and char yields arising from a DDM-cured epoxy resin are usually higher than those of dicyandiamide (DICY) or 2-methylimidazole (2-MI) analogues and the reactivity of epoxy blends with three curing agents presents an increase in the order of 2-MI, DDM and DICY. In general, the tetramethylbisphenol-A (TMBPA)-derived polymer exhibits the lowest T g, char yield and dielectric constant among PPO derivatives whereas the biphenol polymers usually results in higher T g and char yield due to its rigid rod structure.

Curing behavior of epoxy resins with a series of novel curing agents containing 4,4′-biphenyl and varying methylene units

Abstract A new homologous series of curing agents (LCECAn) containing 4,4′-biphenyl and n-methylene units (n = 2, 4, 6) were successfully synthesized. The curing behaviors of a commercial diglycidyl ether of bisphenol-A epoxy (E-51) and 4,4′-bis(2,3-epoxypropoxy)biphenyl (LCE) by using LCECAn as the curing agent have been investigated by differential scanning calorimetry (DSC), respectively. The Ozawa equation was applied to the curing kinetics based upon the dynamic DSC data, and the isothermal DSC data were fitted using an autocatalytic curing model. The glass transition temperatures (Tg) of the cured epoxy systems were determined by DSC upon the second heating, and the thermal decomposition temperatures (Td) were obtained by thermogravimetric (TG) analyses. The results show that the number of methylene units in LCECAn has little influence on the curing temperatures of E-51/LCECAn and LCE/LCECAn systems. In addition, the activation energies obtained by the dynamic method proved to be larger than those b...

Preparation of TiO 2/epoxy nanocomposites by ultrasonic dispersion and their structure property relationship

By the insertion of nanoparticles into a polymer matrix a considerable improvement of mechanical properties can be achieved. Therefore, a homogeneous distribution of fillers within the matrix is required. In the present paper the dispersion of TiO 2-nanoparticles in a DGEBA (diglycidyl ether of bisphenol A) epoxy resin by means of an ultrasonic horn was studied. The systematic examination of process parameters of a previous study was completed in order to determine the optimum processing window leading to a good dispersion result without degrading the molecular structure of the epoxy resin. Therefore, particle sizes were examined using a dynamic light scattering device, and the effect of the ultrasonic treatment on the resin was surveyed by FT-IR spectroscopy (Fourier transform infrared spectroscopy). Furthermore, the mechanical performance of the nanocomposites was examined for various contents of TiO 2-nanoparticles to show that the materials prepared by ultrasonic dispersion show an improved property’s profile. In order to understand the reinforcing mechanisms of nanoparticles in the polymer matrix providing improved mechanical properties, scanning electron microscope (SEM) pictures of the fracture surfaces of the samples were carried out, which revealed that nanocomposites show a significantly rougher surface than the neat epoxy resin. This indicates a change in the fracture mechanisms.

Effect of Hyperbranched Poly (Trimellitic Anhydride Ethylene Glycol) Epoxy (HTME) on Thermal Degradation Activation Energies of HTME/Diglycidyl Ether of Bisphenol-A Epoxy Hybrid Resin by Kissinger and Flynn–Wall–Ozawa Method

The thermal degradation behavior and kinetics of hyperbranched poly (trimellitic anhydride ethylene glycol) epoxy (HTME)/diglycidyl ether of bisphenol-A epoxy (DGEBA) hybrid resin was investigated with thermogravimetric analysis (TGA) by using Kissinger method and Flynn–Wall–Ozawa method. The results show that the thermal degradation activation energies of DGEBA, 9 wt% HTME-1/91wt% DGEBA, 3 wt% HTME-2/97 wt% DGEBA, 9 wt% HTME-2/91 wt% DGEBA, 15 wt% HTME-2/85 wt% DGEBA, and 9 wt% HTME-3/91wt% DGEBA are 152.5, 144.4, 135.4, 133.2, 121.8 and 143.0 kJmol−1, respectively, by Kissinger method. and the activation energies are 173.3, 165.0, 163.2, 151.7, 137.7 and 159.7 kJmol−1, respectively by Flynn–Wall–Ozawa method. With the increase of HTME content, the activation energies of HTME/DGEBA hybrid resin decrease. Although molecular weight or generation of hyperbranched epoxy resins (HTME) has little effect on the thermal degradation activation energies and other kinetics data.

Cationic concentration effects on electron beam cured of carbon-epoxy composites

Electron beam (e-beam) curing is a technology that offers advantages over the thermal curing process, that usually requires high temperature and are time-consuming. E-beam curing is faster and occurs at low temperatures that help reduce residual mechanical stresses in a thermoset composite. The aim of the present study is to analyze the effects of cationic initiator (diaryliodonium hexafluoroantimonate) ranged from 1 to 3 wt% in DGEBA (diglycidyl ether of bisphenol A) epoxy resin when cured by a 1.5 MeV electron beam. The specimens were cured to a total dose of 200.4 kGy for 40 min. Analyses by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) show that the e-beam irradiated samples with 2 wt% cationic initiator were 96% cured obtained a glass transition temperature (tan δ) of 167 °C. The same epoxy resin, thermally cured for 16 h with an anhydride hardener, reached a T g (tan δ) of 136 °C. So, the irradiated sample had its T g increased approximately 20% and the curing process was much less time consuming.

Thermal degradation of a reactive flame retardant based on cyclotriphosphazene and its blend with DGEBA epoxy resin

Hexaglycidyl cyclotriphosphazene (HGCP) was synthesized, and characterized by FTIR, 31P, 1H, and 13C-NMR. This compound was used as a reactive flame retardant to blend with commercial epoxy resin DGEBA (Diglycidyl ether of bisphenol A). Its effect on the DGEBA decomposition pathways was characterized by studying both gas and solid phases produced during thermogravimetric analysis (TGA). The gases evolved during TGA in air were studied by means of thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR), while the solid residues were analysed by FTIR and scanning electron microscopy (SEM). The results showed that HGCP presents a good dispersion in DGEBA, and the blend thermoset with 4,4′-methylene-dianiline (MDA) curing agent leads to a significant improvement of the thermal stability at elevated temperature with higher char yields compared with pure DGEBA thermoset with the same curing agent. Improvement has also been observed in the fire behaviour of blend sample.

Contact allergy to epoxy (meth)acrylates

Contact allergy to epoxy (meth)acrylates, 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (bis-GMA), 2,2-bis[4-(2-hydroxy-3-acryloxypropoxy)phenyl]-propane (bis-GA), 2,2-bis[4-(methacryl-oxyethoxy)phenyl] propane (bis-EMA), 2,2-bis[4-(methacryloxy)phenyl]-propane (bis-MA), and glycidyl methacrylate (GMA) is often manifested together with contact allergy to diglycidyl ether of bisphenol A (DGEBA) epoxy resin. To analyse patterns of concomitant allergic reactions to the five epoxy (meth)acrylates in relation to exposure. We reviewed the 1994-2008 patch test files at the Finnish Institute of Occupational Health (FIOH) for reactions to the five epoxy (meth)acrylates, and examined the patients' medical records for exposure. Twenty-four patients had an allergic reaction to at least one of the studied epoxy (meth)acrylates, but specific exposure was found only in five patients: two bis-GMA allergies from dental products, two bis-GA allergies from UV-curable printing inks, and one bis-GA allergy from an anaerobic glue. Only 25% of the patients were negative to DGEBA epoxy resin. The great majority of allergic patch test reactions to bis-GMA, bis-GA, GMA and bis-EMA were not associated with specific exposure, and cross-allergy to DGEBA epoxy resin remained a probable explanation. However, independent reactions to bis-GA indicated specific exposure. Anaerobic sealants may induce sensitization not only to aliphatic (meth)acrylates but also to aromatic bis-GA.

Thermal degradation and flammability of P/Si polysilsesquioxane epoxy nanocomposites

AbstractA thermal stable epoxy nanocomposite prepared from the 4,4′‐diglycidylether bisphenol A (DGEBA) and the P/Si ladder‐like polysilsesquioxane (PSSQ). The activation energies of thermal degradation were calculated by Kissinger's and Ozawa's methods. The higher ladder‐like PSSQ content not only increase the oligomer content but also generate the steric hindrance. Which steric hindrance influence the epoxy/amine curing reaction of the modified epoxy system was more than the pristine DGEBA epoxy system. The P‐Si synergistic effect on the thermal stability of the nanocomposites was discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Novel Piperazinylo Bisaryl Hydrazino-S-Triazine Derivatives and Their Application as Epoxy Resin Curing Agents

Various 2-(4-ethyl-1-piperazinylo)-4,6-bisarylhydrazino-1,3,5-triazine (3a–f) were prepared by the reaction of 2-(4-ethyl-1-piperazinylo)-4,6-dichloro-1,3,5-triazine and various phenyl hydrazine derivatives. All the 3a–f derivatives were characterized by elemental analysis and IR spectral studies. All the 3a–f compounds were screened for microbial activity against gram-positive and gram-negative bacteria. All these derivatives were employed as the epoxy resin curing agent. Thus the curing of the epoxy diglycidyl ether of bisphenol-A (DGEBA) was monitored by differential scanning calorimeter (DSC). Based on DSC parameters and glass-fiber reinforced composites based on DGEBA-3(a-f) systems were prepared and characterized.

Effects of reactive compatibilizer on the core–shell structured modifiers toughening of poly(trimethylene terephthalate)

Poly(trimethylene terephthalate)/polybutadiene grafted polymetyl methacrylate (PB-g-PMMA, MB) blends were prepared by melt processing with varying weight ratios (0–5wt%) of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin as a reactive compatibilizer. DMA result showed PTT was partially miscible with MB particles in the presence of the compatibilizer. Fourier transform infrared (FTIR) and rheological measurements further identified the reactions between PTT and DGEBA epoxy resin. Scanning electron microscopy (SEM) displayed that the core–shell structured modifiers exhibit a smaller dispersed domain size with the addition of DGEBA epoxy resin. Mechanical tests showed the impact and tensile properties of PTT blends are improved by the introduction of DGEBA epoxy resin to the blends. SEM and TEM results showed shear yielding of PTT matrix and cavitation of rubber particles were the major toughening mechanisms.

Thermal, physical and flame-retardant properties of phosphorus-containing epoxy cured with cyanate ester

Two phosphorus-containing advanced epoxy resins were obtained by chain-extension of diglycidyl ether of bisphenol-A epoxy (DGEBA) resin with 2-(6-oxido-6H-dibenz(c,e)(1,2)-oxaphosphorin-6-yl)-1,4-benzenediol (DOPOBQ), at different stoichiometric ratios. The phosphorus-containing advanced epoxy was separately cured with various dicyanate esters to form flame-retardant epoxy/cyanate ester systems. The effects of phosphorus content and dicyanate ester structure were studied, and compared with those of the control (advanced bisphenol-A epoxy) system. The DOPOBQ-containing epoxy/cyanate ester systems exhibited higher glass transition temperatures, better dimensional stability and better thermal stability.

Thermal and physical properties of flame-retardant epoxy resins containing 2-(6-oxido-6 H-dibenz〈 c, e〉〈1,2〉oxaphosphorin-6-yl)-1,4-naphthalenediol and cured with dicyanate ester

2-(6-oxido-6 H-dibenz( c, e)(1,2)oxaphosphorin-6-yl)-1,4-naphthalenediol (DOPONQ) was prepared by the addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with 1,4-naphthoquinone. The phosphorus-containing diol (DOPONQ) was used as a reactive flame retardant by an advancement reaction with the diglycidyl ether of bisphenol-A epoxy (DGEBA) resin at various stoichiometric ratios. DOPONQ-containing advanced epoxy was separately cured with various dicyanate esters to form flame-retardant epoxy/cyanate ester systems. The effect of the phosphorus content and dicyanate ester structure on the curing characteristic, glass transition temperature, dimensional stability, thermal stability, flame retardancy, and dielectric property was studied and compared with that of the control advanced bisphenol-A epoxy system. The DOPONQ-containing epoxy/cyanate ester systems exhibited higher glass transition temperatures as well as better thermal dimensional and thermal degradation stabilities. The flame retardancy of the phosphorus-containing epoxy/dicyanate ester system increased with the phosphorus content, and a UL-94 V-0 rating could be achieved with a phosphorus content as low as 2.1%.

Studies on the physico-mechanical and thermal characteristics of blends of DGEBA epoxy, 3,4 epoxy cyclohexylmethyl, 3′,4′-epoxycylohexane carboxylate and carboxyl terminated butadiene co-acrylonitrile (CTBN)

Toughening of blend of diglycidyl ether of bisphenol-A (DGEBA) and 3,4 epoxy cyclohexylmethyl, 3′,4′-epoxycylohexane carboxylate, i.e. cycloaliphatic epoxy resin (CAE) with varying weight ratios (0–25 wt%) of carboxyl terminated butadiene acrylonitrile (CTBN) copolymer have been investigated. Fourier transform infrared (FTIR) spectroscopic analysis established that the interaction between oxirane groups of DGEBA, CAE and CTBN were responsible for characteristics peak shifts in the blends compared to their counterparts. Physico-mechanical properties of the prepared samples, e.g. tensile, flexural and impact strengths showed an optimum concentration of CTBN (15 wt%) into epoxy matrix, which offered maximum toughening. Thermal stability of the prepared samples was analyzed by dynamic thermogravimetric runs. Cross-sections of the cured samples which failed during impact testing have been critically studied through scanning electron microscopic (SEM) analysis to gain insight into the phase morphology.

Simultaneous improvements in the cryogenic tensile strength, ductility and impact strength of epoxy resins by a hyperbranched polymer

Improvements in mechanical properties at low temperatures are desirable for epoxy resins such as diglycidyl ether of bisphenol A (DGEBA) that are often used in cryogenic engineering applications. In this study, a hydroxyl functionalized hyperbranched polymer (H30) is employed to improve the mechanical properties of a DGEBA epoxy resin at liquid nitrogen temperature (77K). The results show that the tensile strength, failure strain (ductility) and impact strength at 77K are simultaneously improved by adding a proper content of H30. The maximum tensile strength at 77K is increased by 17.7% from 98.2MPa of pure epoxy resin to 115.6MPa of modified epoxy system for the 10wt% H30 content. The failure strain at 77K increases consistently with the increase of H30 content. The maximum impact strength at 77K is attained by introduction of 10wt% H30 with an improvement of 26.3% over that of pure epoxy resin. For the purpose of comparison, the mechanical properties of modified epoxy resins at room temperature (RT) are also investigated. It is interesting to note that the impact strength is not lower at 77K than that at RT for the modified systems. Moreover, the glass transition temperature (Tg) is not reduced by the addition of H30 in appropriate amounts.

Influence of the proportion of ytterbium triflate as initiator on the mechanism of copolymerization of DGEBA epoxy resin and γ-butyrolactone

Non-isothermal differential scanning calorimetry (DSC) experiments were performed to study the kinetics of the curing process of mixtures of diglycidylether of bisphenol A (DGEBA) and γ-butyrolactone (γ-BL) with ytterbium triflate as an initiator. It can be deduced that the cured material consists of epoxide homopolymers with incorporated poly(ether-ester) unities, which come from the lactone incorporated into the network. The kinetic parameters, obtained using the non-isothermal isoconversional procedure, show not only the importance of the proportion of initiator but also the influence of γ-butyrolactone on the polymerization of DGEBA. The homopolymerization of DGEBA catalyzed by ytterbium triflate has an activation energy of 85.3 kJ mol−1, which decreases to 68.2 kJ mol−1 in the presence of γ-butyrolactone forming copolymers. Analysis from DSC and FTIR data showed that, when the proportion of ytterbium triflate was increased, the reaction process accelerated and the mechanism of the cationic non-linear polymerization named activated monomer (AM) became more evident than the activated chain-end mechanism (ACE). Finally, the activation energies and the pre-exponential factors were determined for both mechanisms.

Thermomechanical behavior of epoxy resins modified with epoxidized vegetable oils

AbstractBiobased epoxy materials were prepared from diglycidyl ether of bisphenol A (DGEBA) and epoxidized vegetable oils (EVOs) (epoxidized soybean oil and epoxidized castor oil) with a thermally latent initiator. The effects of EVO content on the thermomechanical properties of the EVO‐modified DGEBA epoxy resins were investigated using several techniques. Differential scanning calorimetry indicated that the cure reaction of the DGEBA/EVO systems proceeded via two different reaction mechanisms. Single and composition‐dependent glass transition temperature (Tg) mechanisms were observed for the systems after curing. The experimental values of Tg could be explained by the Gordon–Taylor equation [Gordon M and Taylor JS, J Appl Chem 2:493 (1952)]. The thermal stability of the systems decreased as the EVO content increased, due to the lower crosslinking density of the DGEBA/EVO systems. The coefficient of thermal expansion of the systems was found to increase linearly with increasing EVO content. This could be attributed to the fact that the degrees of freedom available for motions of the segments of the macromolecules in the network structure were enhanced by the addition of EVO. Copyright © 2008 Society of Chemical Industry