Morphology and thermal properties of organic–inorganic hybrid material involving monofunctional-anhydride POSS and epoxy resin
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Diglycidyl ether
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Abstract Variation of the epoxy/curing agent ratio by as much as ±10 wt% from the stoichiometric ratio for a system containing a diglycidyl ether of bisphenol‐A (DGEBA) and a mixed aromatic amine was found to have a significant effect on the cure kinetics as determined by dynamic mechanical measurements. A sample preparation technique was developed for monitoring the cure of glass reinforced epoxy in flexure. Shear measurements were also made on the neat resin. From gel time flexural data, the activation energy of cure passed through a maximum at the stoichiometric ratio of epoxy/amine for a glass cloth composite. In shear for the neat resin, a minimum was observed. By considering the curing of the mixed system to follow third‐order kinetics, overall reaction rate constants were estimated after the gel point.
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The epoxy resin diglycidyl ether of bisphenol F (DGEBF) was cured by the aliphatic amine curing agent Epicure 3371 in a stoichiometric ratio both frontally and in a batch-cure schedule. Glass transition temperatures (Tg) were determined using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). DMA also was used for studying the storage modulus (E′) and tan delta (tan δ) of the cured samples. Tensile properties of epoxy samples were tested according to ASTM D638M-93. The properties of the frontally cured epoxy resin were found to be very close to that of batch-cured epoxy resin. Velocity of cure-front propagation was measured for both neat and filled epoxy. Rubber particles (ground tires) were used as a filler. The maximum percentage of filler in the epoxy resin allowing propagation was 30%. Because of convection, only descending fronts would propagate. Advantages and disadvantages of frontal curing of epoxy resins are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1209–1216, 1997
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We have prepared epoxy/polyhedral oligomeric silsesquioxane (POSS) nanocomposites by photopolymerization from octakis(glycidylsiloxy)octasilsesquioxane (OG) and diglycidyl ether of bisphenol A. We used nuclear magnetic resonance, Raman, and Fourier transform infrared spectroscopies to characterize the chemical structure of the synthetic OG. Differential scanning calorimetry and dynamic mechanical analysis (DMA) revealed that the nanocomposites possessed higher glass transition temperatures than that of the pristine epoxy resin. Furthermore, DMA indicated that all of the nanocomposites exhibited enhanced storage moduli in the rubbery state, a phenomenon that we ascribe to both the nano-reinforcement effect of the POSS cages and the additional degree of crosslinking that resulted from the reactions between the epoxy and OG units. Thermogravimetric analysis revealed that the thermal stability of the nanocomposites was better than that of the pristine epoxy.
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Diglycidyl ether
Thermogravimetric analysis
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Abstract 0.5–3 wt% nanosilica was added to an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) and cured at 25, 40 or 60 °C using isophoronediamine (IPDA) as hardener. Aggregates of nanosilica were properly dispersed into the DGEBA‐IPDA resin and agglomerates formation was avoided. Addition of nanosilica increased the storage modulus E′ and the area and height of the tan δ curve of DGEBA‐IPDA resin cured at 25 °C, but no significant differences were found by curing at higher temperature. Gel time measurements and the results obtained by applying the Kamal model to isotherm DSC curing of DGEBA‐IPDA‐nanosilica revealed that nanosilica catalysed the curing reaction between DGEBA and IPDA, in less extent by increasing the curing temperature.
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The epoxy resin diglycidyl ether of bisphenol F (DGEBF) was cured by the aliphatic amine curing agent Epicure 3371 in a stoichiometric ratio both frontally and in a batch-cure schedule. Glass transition temperatures (Tg) were determined using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). DMA also was used for studying the storage modulus (E′) and tan delta (tan δ) of the cured samples. Tensile properties of epoxy samples were tested according to ASTM D638M-93. The properties of the frontally cured epoxy resin were found to be very close to that of batch-cured epoxy resin. Velocity of cure-front propagation was measured for both neat and filled epoxy. Rubber particles (ground tires) were used as a filler. The maximum percentage of filler in the epoxy resin allowing propagation was 30%. Because of convection, only descending fronts would propagate. Advantages and disadvantages of frontal curing of epoxy resins are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1209–1216, 1997
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Diglycidyl ether
Thermogravimetric analysis
Silsesquioxane
Degradation
Thermal Stability
Thermomechanical analysis
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The title nonionic waterborne low temperature epoxy curing agent was prepared with polyglycol diglycidyl ether,bisphenol A epoxy resin,aliphatic or aromatic amine.The effect of valieties of amine and the content of polyglycol diglycidyl ether low on the appearance,stability and curing properties of the curing agent was investigated.The film formation process waterborne epoxy system and its pot life,the effect of ratio(hydroxyl group/ epoxy group) on film properties was discussed.
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By means of fourier transform infrared(FTIR), the curing kinetics of bisphenol-S epoxy resin/DDS and tetrabromo-bisphenol-A epoxy resin/DDS at constant temperature were studied, and the apparent activation energy was obtained. The reaction mechanism of bisphenol-S epoxy resin/DDS and tetrabromo-bisphenol-A epoxy resin/DDS system were also investigated.
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Octa(aminpropyl)silsesquioxane (NH 2 CH 2 CH 2 CH 2 ) 8 Si 8 O 12 (POSS-NH 2 ), containing eight amine groups on the vertexes, was first used as the curing agent for epoxy resin diglycidyl ether of bisphenol A(DGEBA) in order to improve the overall performance of epoxy resins, such as mechanical properties, thermal resistance and dielectric properties. The disappearance of epoxy groups on the FT-IR spectra at the end of the curing process indicated that epoxy groups reacted with POSS to form a three-dimensional crosslinking network, and the epoxy resin was completely cured. Properties of the cured DGEBA/POSS nanocomposite containing 30wt% of POSS-NH 2 were studied. SEM images of the flexural fractures of epoxy/POSS system indicated that the inorganic-organic materials possessed excellent toughness. TGA analysis revealed that the cured network showed enhanced thermal stability with respect to the cured DGEBA/DDS system.
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Diglycidyl ether
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This paper introduces flame-retardant organic–inorganic hybrid epoxy composites possessing excellent comprehensive performance, which results from the phosphorus–silicon synergistic flame retardant effect of the glycidyl POSS and DOPO derivative.
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