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Cure reactions of the stoichiometric mixtures of diglycidyl ether of bisphenol A (DGEBA) and two very low molecular weight aliphatic polyether diamines (PED) were studied by using fluorescence and mid- and near-IR spectroscopic techniques. As the cure proceeded, the primary amine groups in PED are converted to the secondary and the tertiary amines. Near-IR spectral analysis was used to calculate the...
After fabrication of an epoxy system filled with aluminum powder, followed by inelastic deformations under compression of the specimens, Positron Annihilation Lifetime Spectroscopy (PALS) was used to follow the evolution of the free-volume holes in the matrix. In order to describe the micromechanical deformation mechanism that takes place in the matrix around the inclusions, the experimental free-volume...
The morphology of stoichiometric initially immiscible reactive blends of DGEBA epoxy resin and poly(3-aminopropylmethylsiloxane) has been characterized by laser scanning confocal microscopy. Observations were done on samples cured isothermally at different curing temperatures in the range 20–120°C as well as in situ and in real time at 60°C. Three different processes were revealed: coalescence, which...
Dielectric properties of three curing epoxy resin systems at an industrial microwave frequency, 2.45GHz, were measured over a temperature range lower than the cure temperature. Extent of cure, which is determined by DSC, is used to describe the progress of the polymerization. It has been found that, normally, the real and the imaginary part of the complex dielectric constant increased with temperature...
Photoluminescence features in a commercial grade cured DGEBA-based epoxy resin have been investigated with as objective to determine which of the material compounds are responsible for cured resin emissions. The origin of the bands has been approached by considering photoluminescence of base resin and hardener taken separately, of their mixture, and in the course of curing. Most of the bands observed...
Dielectric relaxation measurements are reported over a frequency range from 10 −1 to 10 9 Hz as a function of exposure time for an epoxy resin–carbon fibre composite, ageing at 60°C in water. Investigation of the nature of the dipole relaxation of the water molecules, indicates the nature of their interaction with the polymer matrix. Analysis of the dielectric relaxation spectra allow...
In 1996, the authors proposed a novel method to prepare micron-sized, hollow cross-linked polymer particles. This method is based on the self-assembling of phase separated polymer at interface with water, which was named SaPSeP method, formed by suspension polymerization of divinyl monomer in toluene droplet dissolving previously polystyrene. The SaPSeP method was developed to be applicable to polyaddition...
The octaammonium chloride salt of octaaminopropyl polyhedral oligomeric silsesquioxane (OapPOSS) was synthesized via the hydrolytic condensation of γ-aminopropyltrimethoxysilane in the methanol solution catalyzed by concentrated hydrochloric acid and was further used as the intercalating agent to modify sodium montmorillonite (MMT). X-ray diffraction (XRD) data indicate that the MMT was successfully...
A nanoporous polyhedral oligomeric silisesquioxane (POSS) containing eight epoxy functional groups [octakis(dimethylsiloxypropylglycidyl ether)silsesquioxane, OG] reacts with meta-phenylenediamine (mPDA) to form epoxy resin network with nanostructures. The glass transition temperature (T g ) of the cured OG/mPDA product is significantly higher than that of the diglycidyl ether of bisphenol...
The organic-inorganic hybrids involving epoxy resin and polyhedral oligomeric silsesquioxanes (POSS) were prepared via in situ polymerization of diglycidyl ether of bisphenol A (DGEBA) and 4,4'-diaminodiphenylmethane (DDM) in the presence of the two structurally similar POSS monomers. The organic groups on silsesquioxane cage are aminophenyl and nitrophenyl groups, respectively. The curing reactions...
Novel reactive core/shell-type hyperbranched blockcopolyethers were tailored as new class of liquid rubbers useful as flexibilizers and toughening agents of anhydride-cured epoxy resins. Anionic ring-opening polymerization of glycidol onto a six-arm star poly(propylene oxide-block-ethylene oxide) afforded hyperbranched polyether cores as macroinitiators for propylene oxide graft copolymerization....
The glass transition temperatures of nine stoichiometric resin systems of tetraglycidyl-4,4'-diamino-diphenylmethane (TGDDM), triglycidyl p-amino phenol and diglycidyl ether of bisphenol A with 4,4'-diaminodiphenylsulphone (DDS), diethyl-toluenediamine and dimethylthiotoluenediamine were calculated using group interaction modelling (GIM) and atomic additivity (AA) methods. The input parameters were...
This paper studies the phase separation in poly(ether imide) (PEI) modified epoxy resin using imidazole (C 11 Z-CNS) as epoxy hardener to control its morphology. The sponge-like phase structures were founded at higher PEI concentration (10-25phr), while homogeneous structures are formed at low PEI concentration (5phr). The effects of PEI concentration on curing kinetics and phase structures...
The synthesis of novel epoxy resin containing both naphthalene moiety and cycloaliphatic group by chemical bonding in the same molecule has been conducted starting from naphthol and limonene. Its chemical structure was characterized with FTIR spectroscopy, NMR, and GPC analyses. Dynamic cure behaviors with different curing agents were investigated using differential scanning calorimetry. The physical...
A hybrid monomer of 4-(N-maleimidophenyl)glycidylether (MPGE), which possesses both oxirane ring and maleimide curable groups, was first synthesized from N-(4-hydroxyphenyl)maleimide and epichlorohydrin by using benzyltrimethylammonium chloride as a catalyst. MPGE was then cured with amine compounds (DDM and DICY) and diethylphosphite (DEP) to result in crosslinking networks. The curing kinetics and...
Epoxy-silica nanocomposites were obtained from directly blending diglycidylether of bisphenol-A and nanoscale colloidal silica and then curing with 4,4-diaminodiphenylmethane. The epoxy-silica nanocompoites showed good transparency and miscibility observed with AFM, SEM, and TEM. The thermal stability of the epoxy resins was improved with the incorporation of the colloidal silica. However, a depression...
Polybutylene terephthalate (PBT), a versatile engineering thermoplastic, has been processed using epoxy resin as a reactive solvent. Following processing of this blend, the epoxy was cured using a bi-functional amine curing agent, resulting in phase separation and phase inversion thus producing a different morphology. Change in crystallization kinetics of PBT in the presence of the epoxy monomer and...
The effect of physical aging and side group on the free volume has been studied by positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimeter (DSC) for a series of epoxy resins cured separately with novolac resin and esterified novolac resins, that is, the hydroxyl group of phenol novolac resin was placed by a CH 3 COO-group, a CH 3 CH 2 CH ...
In certain applications of fiber reinforced polymer composites flexibility is required. The aim of this study was to improve flexibility of short glass fiber reinforced epoxy composites by using a liquid elastomer. For this purpose, diglycidyl ether of bisphenol-A (DGEBA) based epoxy matrix was modified with hydroxyl terminated polybutadiene (HTPB). A silane coupling agent (SCA) was also used to improve...
Previous published work has shown that hydroxyl terminated perfluoroether oligomers can be suitably modified and functionalised to make them miscible with epoxy resins in the uncured state. The reaction conditions can adjusted to induce phase separation either through spinodal decomposition to produce an IPN type morphology, or by nucleation and growth if a dispersed-particle microstructure is required...
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