Diglycidyl Ether Of Bisphenol A System Research Articles

Effect of Zinc Oxide Nanoparticles on Mechanical Properties of Diglycidyl Ether of Bisphenol-A

This study reports on the synthesis of zinc oxide (ZnO) nanostructures and examines the performance of polymer nanocomposites fabricated using ZnO dispersed in polymer host matrices. The polymer matrix used was an epoxy based thermosetting polymer known as Diglycidyl Ether of Bisphenol-A(DGEBA). Zinc oxide nano particles were prepared by precipitation method using Poly Vinyl Alcohol as the surface modifier. It was characterized using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). And the average particle size has been found to be 25 nm. The main objective of this study is to investigate the simultaneous effect of the additive ZnO nanoparticles and curing agent on the curing kinetics, mechanical and morphological properties of Diglycidyl ether of bisphenol-A system. The mechanical properties of epoxy resin based on diglycidyl ether of bisphenol-A and Zinc Oxide were also investigated and improved mechanical properties were obtained for epoxy resin with 2% filler concentration.

Effect of functionalized magnetite nanoparticles and diaminoxanthone on the curing, thermal degradation kinetic and corrosion property of diglycidyl ether of bisphenol A-based epoxy resin

To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone (DAX) was used to cure diglycidylether of bisphenol-A (DGEBA)-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.

Effect of Reactive Diluents on the AC Electrical Treeing in Epoxy/Nanosilicate Systems

The effect of reactive diluents on the ac electrical treeing in epoxy/nanosilicate systems was studied, in a needle-plate electrode geometry. Diglycidyl ether of bisphenol A (DGEBA) type epoxy was used as a base resin, and layered silicate was used as a nano-sized filler. Polyglycol (PG) or 1,4-butanediol diglycidyl ether (BDGE) was introduced as a reactive diluent to the DGEBA/nanosilicate system, in order to decrease the viscosity of the nanocomposite system. PG acted as a flexibilizer, and BDGE acted as a chain extender, after the curing reaction. To measure the treeing propagation rate, a constant alternating current (ac) of 10 kV/4.2 mm (60 Hz) was applied to the specimen, in a needle-plate electrode arrangement, at <TEX>$30^{\circ}C$</TEX> of insulating oil bath. When 10 kV/4.2 mm (60 Hz) was applied, the treeing propagate rate in the DGEBA system was <TEX>$1.10{\times}10^{-3}$</TEX> mm/min, and that in the DGEBA/PG system was <TEX>$1.05{\times}10^{-3}$</TEX> mm/min. As 1.5 wt% of nanosilicate was added to the DGEGA/PG system, the propagation rate was <TEX>$0.33{\times}10^{-3}$</TEX> mm/min. This meant that the nano-sized layered silicates would act as good barriers to treeing propagation. The effect of chlorine content was also studied, and it was found that chlorine had a bad effect on the electrical insulation property of the epoxy system.

Effect of Electric Frequency on the Partial Discharge Resistance of Epoxy Systems with Two Diluents

Partial discharge resistance for the epoxy systems with two diluents was investigated in the rod-plane electrodes arrangement, and the effect of electric frequency on the partial discharge resistance was also studied. Diglycidyl ether of bisphenol A (DGEBA) type epoxy was used as a base resin, and 1,4-butanediol diglycidyl ether (BDGE) or polyglycol (PG) as a reactive diluent was introduced to the DGEBA system, in order to decrease the viscosity of the DGEBA epoxy system. BDGE was acted as a chain extender, and PG acted as a flexibilizer, after the curing reaction. To measure the partial discharge resistance, 5 kV alternating current (ac) with three different frequencies (60, 500 and 1,000 Hz) was applied to the specimen in a rod-plane electrode arrangement, at <TEX>$30^{\circ}C$</TEX>. PG had a good effect, while BDGE had a bad effect on the partial discharge resistance of the DGEBA system, regardless of the electric frequency.

Preparation and Characterization of Cyclohexyl Moiety Toughened POSS-Reinforced Epoxy Nanocomposites

Polyhedral oligomeric silsesquioxane (POSS)-reinforced epoxy nanocomposites were prepared by reacting commercially available diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM) epoxy resins with 1,1-bis(3-methyl-4-glycidyloxyphenyl)cyclohexane (Cy-Ep) separately and reinforced with POSS nanocluster. POSS (OAPS)-reinforced hybrid Cy-Ep-epoxy resin castings were characterized for their mechanical and morphological properties. The data obtained from mechanical studies indicated that the incorporation of nano OAPS into Cy-Ep modified hybrid systems results in improved stability. Among the epoxy systems studied, the TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher than that of the TGDDM system. The dispersion of POSS was confirmed by scanning electron microscopy and visual observation studies.

Thermal and Dielectric Properties of Inorganic-Organic Nanocomposites Involving Epoxy Resin and Polyhedral Oligomeric Silsesquioxanes

In this paper, a type of nanoporous polyhedral oligomeric silisesquioxanes (POSS) containing eight functional groups have been synthesized and mixed with diglycidyl ether of bisphenol A (DGEBA) to form epoxy resin networks with nanostructures. The cured octa(aminophenyl) silsesquioxane (1c-POSS) and DGEBA system inherently possesses higher thermal stability and higher char yield than the control epoxy resins. Furthermore, the dielectric constant of the 1c-POSS/DGEBA material (4.36) is substantially lower than that of the neat epoxy resins (4.64) as a consequence the presence of nanoporous POSS cubes in the epoxy matrix.

Mechanical and Thermal Properties of Chemically Modified Epoxy Resin

Diglycidyl ether of bisphenol-A (DGEBA), having number average molecular weight (Mn) 375, was modified by incorporating the hydroxyl terminated polybutadiene (HTPB) based prepolymer using isophorone diisocyanate as a coupling agent. To increase the compatibility between the epoxy resin and HTPB part, polar groups were introduced in the later to achieve physical and chemical interactions between the two phases. The finally modified DGEBA system was cured with amine based hardener. FTIR and 1H-NMR were used to monitor the whole modification procedure. The rubber particles size and distribution was monitored as a function of HTPB contents in the resin system using scanning electron microscopy (SEM). The mechanical, thermal and thermo-mechanical properties have shown that the tensile strength, toughness, ductility and impact strength of the modified cured system have been successfully increased at some optimum HTPB contents without affecting the inherent thermal and thermo-mechanical stability associated with DGEBA resin system. Some of the mechanical properties like flexural modulus, tensile modulus and compressive strength decreased with increasing rubber contents.

Synthesis and characterization of 1, 1-bis (3-methyl-4-epoxyphenyl) cyclohexane-toughened DGEBA and TGDDM organo clay hybrid nanocomposites

1,1-bis (3-methyl-4-epoxyphenyl) cyclohexane (BMEPC) was synthesized from 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane and 2-(chloromethyl) oxirane, and its structure was confirmed by Fourier transform infrared (FT-IR), 1H-, 13C-NMR and electron impact-mass spectrometry. Both diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamine diphenyl methane (TGDDM) epoxy resins were toughened with BMEPC using 4,4′-diaminodiphenylmethane (DDM) as a curing agent. Epoxy and BMEPC-toughened epoxy systems were further modified with organophilic MMT (OMMT) clay. The chemical reactions involved between epoxy and DDM with OMMT was confirmed by FT-IR. OMMT clay-filled hybrid BMEPC-epoxy resin castings were characterized for their mechanical, thermal, thermo-mechanical and morphological properties. The values of Tg and heat distortion temperature of hybrid epoxy decreased with increasing incorporation of OMMT. The data obtained from thermal studies indicated that the incorporation of nano clay into BMEPC-modified hybrid systems possess improved thermal stability. The mechanical properties were studied as per ASTM standards. The TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher when compared with that of the TGDDM system. The values of dielectric constant (ϵ′) and dielectric loss (ϵ′′) were increased with increased incorporation of OMMT clay in both systems. From the X-ray diffraction analysis it was observed that the absence of d001 reflections in OMMT-filled BMEPC-modified epoxy systems indicated the formation of exfoliated nano hybrids. The homogenous morphologies were ascertained from scanning electron microscope and transmission electron microscope.

Curing of DGEBA epoxy resin by low generation amino‐group‐terminated dendrimers

AbstractLow generation amino‐group‐terminated poly(ester‐amine) dendrimers PEA1.0 (NH2)3 and PEA1.5 (NH2)8, and poly(amido‐amine) dendrimer PAMAM1.0 (NH2)4 were used as diglycidyl ether of bisphenol A (DGEBA) epoxy resin hardeners. Thermal behavior and curing kinetics of dendrimer/DGEBA systems were investigated by means of differential scanning calorimetry (DSC). Compared with ethylene diamine (EDA)/DGEBA system, the dendrimer/DGEBA systems gradually liberated heat in two stages during the curing process, and the total heat liberated was less. Apparent activation energy and curing reaction rate constants for dendrimer and EDA/DGEBA systems were estimated. Thermal stabilities and mechanical properties of cured thermosetting systems were examined as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3902–3906, 2006

Thermal and mechanical characterisation of intercalated epoxy nanocomposites

Intercalated epoxy-layered silicate nanocomposites have been prepared using epoxy resins of varying functionalities. Diglycidyl ether of bisphenol A (DGEBA), triglycidyl p-amino phenol (TGAP) and tetraglycidyl diamino diphenylmethane (TGDDM) were mixed with 2.5–10 wt.-%; of an organophilic modified layered silicate and cured with diethyltoluene diamine. The d-spacing of the layered silicates in the cured resin system was determined by wide angle X-ray analysis. The catalytic influence of the clay on the bifunctional DGEBA system was investigated by differential scanning calorimetry (DSC). Dynamic mechanical thermal analysis (DMTA) was used to investigate the glass transition temperatures of the three different resin systems and therefore the changes in the network structure as a result of the incorporation of the clay content. Fracture measurements showed an increasing toughness of the nanocomposites with increasing clay content in all systems.

Preparation and properties of polydimethylsiloxane-modified epoxy resins

In this work, polydimethylsiloxane (PDMS) with different molecular weight were used to modify diglycidyl ether of bisphenol A (DGEBA). A PDMS-block-DGEBA copolymer that acted as a compatibilizer was prepared via DGEBA, hydroxy terminated PDMS, and silane coupling agent in the presence of a catalyst. The reaction mechanisms and compatibilizing effects of the block copolymer were studied by means of Fourier transform infrared (FTIR) spectrum analysis and observation under scanning electron microscopy (SEM). The thermal and mechanical behaviors were analyzed as well. Results indicated that the block copolymer has good compatibilizing effect, and PDMS with low molecular weight could be dispersed in the DGEBA matrix more evenly. Moreover, the PDMS modified DGEBA systems had higher impact strength and lower weight loss rate than those of the pristine DGEBA system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1683–1690, 2000

The preparation and morphology of PPO–epoxy blends

AbstractPoly(phenylene oxide) (PPO) was found to be miscible in diglycidyl ether of bisphenol A (DGEBA) based epoxy. The PPO–DGEBA system exhibited upper critical solution temperature (UCST) behavior. The cloud point temperatures were measured and found to be sensitive to the mol wt of the epoxy resin. A series of PPO‐modified epoxies were cured with piperidine at 160°C, which is above the cloud point temperature. Upon cure, two phase solids were formed, which contained discrete PPO particles. However, the two‐phase particulate morphology was not uniform and numerous large, occluded PPO particles were observed. In order to improve the uniformity, several styrene‐maleic anhydride copolymers were evaluated as potential surfactants for PPO‐DGEBA bends. The formation of a uniform, particulate morphology was facilitated by the addition of a styrene–maleic anhydride copolymer, containing a 10:1 ratio of styrene to maleic anhydride. To our knowledge, this is the first time that an emulsifying agent has been added to improve the morphology of thermoplastic modified epoxies. © 1993 John Wiley &amp; Sons, Inc.

Castor-oil-modified epoxy resins as model systems of rubber-modified thermosets. 1: Thermodynamic analysis of the phase separation

Castor oil (CO) was used to replace polydisperse commercial rubbers (carboxy- or epoxy-terminated butadiene-acrylonitrile random copolymers, CTBN or ETBN) in model systems developed to analyse the origin of the phase separation process in rubber-modified thermosets. Mixtures of CO with an epoxy resin based on the diglycidyl ether of bisphenol A (DGEBA) showed a higher miscibility than a typical CTBN (18% acrylonitrile)-DGEBA system. Thermodynamic factors accounting for this behaviour are discussed using the Flory-Huggins lattice model. Addition of a stoichiometric amount of ethylenediamine (EDA) to a DGEBA-CO solution increased the miscibility. A pseudo-binary approach was used to fit the cloud point curve up to 30% volume fraction of CO. Percentage conversions at the cloud point during the DGEBA-EDA polymerization were experimentally determined and compared with theoretical predictions using the pseudo-binary approach in the framework of the Flory-Huggins lattice model. Reasonable agreement was found, giving direct evidence of the fact that phase separation results from the decrease in the entropic contribution to the free energy of mixing during polymerization.