In this paper, polyether-grafted-epoxide polysiloxane (FEPMS) was synthesized via hydrosilylation among poly(methylhydrosiloxane) (PMHS), allyl polyoxyethylene polyoxypropylene ether (F6) and allyl glycidyl ether to modify Diglycidyl Ether of Bisphenol A (DGEBA). The morphology, thermal properties, and toughness of all cured samples were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and impact testing. Results indicated that grafted polysiloxane can be well dispersed in epoxy matrix, and the epoxy resin modified with FEPMS at relatively low addition levels exhibited higher thermal properties and improved toughness than the neat epoxy resin. 相似文献
A new curing agent based on palmitoleic acid methyl ester modified amine (PAMEA) for epoxy resin was synthesized and characterized. Diglycidyl ether of bisphenol A (DGEBA) epoxy resins cured with different content of PAMEA along with diethylenetriamine (DETA) were prepared. The mechanical properties, dynamic mechanical properties, thermal properties, and morphology were investigated. The results indicated that the PAMEA curing agent can improve the impact strength of the cured epoxy resins considerably in comparison with the DETA curing agent, while the modulus and strength of the cured resin can also be improved slightly. When the PAMEA/epoxy resin weight ratio is 30/100, the comprehensive mechanical properties of the cured epoxy resin are optimal; at the same time, the crosslinking density and glass transition temperature of the cured epoxy resin are maximal. 相似文献
Amine terminated poly(ether sulfone imide) (PESI) with various imide and ethersulfone contents but similar polymer molecular weights were blended with diglycidyletherbisphenol-A (DGEBA) and cured with diaminodiphenylsulfone (DDS). The imide group, a tertiary amine, is a catalyst of the curing reaction of DGEBA with DDS, but it is poorly compatible with uncured epoxy resin. The ethersulfone group is not a catalyst of the curing reaction of DGEBA with DDS, but it has a similar chemical structure as DDS and is compatible with epoxy resin while it is at a low degree of curing. Since PESIs used in this study had similar molecular weights, increasing imide content of PESI would reduce ethersulfone content. The influence of imide and ethersulfone contents of PESI on the phase separation and curing reaction of DGEBA/DDS/PESI blend was investigated using differential scanning calorimetry (DSC), time-resolved light scattering (TRLS), and polarized optical microscopy (POM). Though the imide group has a catalysis effect on the curing reaction of DGEBA with DDS, however, its poor compatibility with epoxy resin retards the curing reaction. Our experimental results revealed the morphology of the cured blends and the curing behavior was a compromise result of catalysis and compatibility of PESI with epoxy resin. 相似文献
The cure kinetics and morphology of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified with a poly (ether ether ketone) based on tertiary butyl hydroquinone (PEEK-T) cured with diamino diphenyl sulphone (DDS) were investigated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical thermal analysis (DMTA). The results obtained from DSC were applied to autocatalytic and diffusion controlled kinetic models. The reaction mechanism broadly showed autocatalytic behaviour regardless of the presence of PEEK-T. At higher PEEK-T concentration, more diffusion controlled mechanism was observed. The rate of curing reaction decreased with increase in thermoplastic content and also with the lowering of curing temperature. The activation energies of the blends are higher than that of the neat resin. The blends showed a phase separated morphology. The dispersed phase showed a homogeneous particle size distribution. The Tg of the neat resin decreased with the decrease in cure temperature. Two Tg's corresponding to the epoxy rich and thermoplastic rich phases were observed in the dynamic mechanical spectrum. The storage modulus of 10 and 20 phr PEEK-T blends are found to be greater than the neat resin. 相似文献
Summary: The epoxy copolymers containing sulfone groups, diglycidyl ether of bisphenol‐A – Bisphenol‐S (DGEBA‐S) were synthesized by a hot‐melt method. The thermal properties of the epoxy systems initiated by two cationic latent catalysts, i.e., N‐benzylpyrazinium hexafluoroantimonate (BPH) and N‐benzylquinoxalinium hexafluoroantimonate (BQH), were investigated by using a dynamic DSC, DMA, and TGA. The mechanical properties were measured by single‐edge‐notched (SEN) beam fracture toughness tests. As a result, the thermal stability and mechanical interfacial properties of the DGEBA‐S/catalyst system were found to be higher than those of the DGEBA/catalyst. This was probably due to the fact that the introduction of sulfone groups with a polar nature to the main chain of the epoxy resins led to an improvement of thermal stability and toughness of the cured epoxy copolymers.
Conversion of the epoxy/catalyst systems as a function of curing temperature. 相似文献
Various amounts of dicyandiamide (Dicy), two grades of epoxy resins, i.e. Epiran 06 and Epikote 828, and three different accelerators including benzyl dimethyl amine (BDMA), 3-(4-chlorophenyl)-1,1-dimethyl urea (Monuron) and 2-methyl imidazole (Im) were used in curing of Dicy/epoxy resin system. Both of the used epoxy resins were based on diglycidyl ether of bisphenol A (DGEBA). The effects of type and concentration of accelerators on curing behavior were studied by differential scanning calorimetry (DSC) method in dynamic or non-isothermal mode. The optimum concentration of Dicy for curing of epoxy resins was obtained based on the glass transition temperature of the cured epoxy/Dicy formulations. The maximum glass transition temperature of 139 °C was obtained at the stoichiometric ratio of Dicy to epoxy of 0.65. The results showed that BDMA has a broader curing peak in DSC and starts the cure reaction earlier than the others. However, Monuron has a narrow curing reaction peak with good cure latency. The tensile properties of Dicy-cured Epiran 06 and Epikote 828 epoxy resins reinforced with chopped strand mat showed that these two epoxy resins have similar mechanical properties. For composites based on the Epiran 06 and Epikote 828 reinforced with 40 wt % glass chopped strand mat, tensile strength and modulus were 156 and 153.4 MPa and 11.6 and 12.4 GPa, respectively. 相似文献
Diglycidyl ether of bisphenol fluorene (DGEBF), 9,9-bis-(4-aminophenyl)-fluorene (BPF) and 9,9-bis-(3-methyl-4-aminophenyl)-fluorene (BMAPF) were synthesized to introduce more aromatic structures into the epoxy systems, and their chemical structures were characterized with FTIR, NMR and MS analyses. The curing kinetics of fluorenyl diamines with different epoxy resins including DGEBF, cycloaliphatic epoxy resin (TDE-85) and diglycidyl ether of bisphenol A (DGEBA) was investigated using non-isothermal differential scanning calorimetry (DSC), and determined by Kissinger, Ozawa and Crane methods. The thermal properties of obtained polymers were evaluated with dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results show that the values of activation energy (Ea) are strongly dependent on the structures of epoxy resin and curing agent. The curing reactivity of epoxy system is restrained by the introduction of rigid fluorene into chain backbone and flexible methyl into side groups. The cured DGEBF/fluorenyl diamine systems exhibit remarkably higher glass transition temperature, better thermal stability and lower moisture absorption compared to those of DGEBA/fluorenyl diamine systems, and display approximate heat resistance and much better moisture resistance relative to those of TDE-85/fluorenyl diamine systems. 相似文献
DGEBA (diglycidyl ether of bisphenol A)–ATBN (amine terminated butadiene acrylonitrile copolymer) blends exhibited upper critical solution temperature (UCST) behavior. Triethylene tetramine (TETA) was introduced as an amine curing agent of epoxy. The real-time phase separation behavior of ATBN-added epoxy system during cure was investigated using laser light scattering. SEM (scanning electron microscopy) and optical microscopy were also employed to observe the morphology of the epoxy blends. Since the DGEBA–ATBN blends showed UCST behavior, the degree of phase separation when cured at low temperature was higher than that when cured at high temperature. The domain correlation length increased as the curing temperature was lowered. Dynamic mechanical analysis (DMA) results indicated that the phase inversion occurred above 20 wt% of ATBN composition. 相似文献
New curing agents 2,5-diamino-1,3,4-thiadiazole (DATD) and N-(4-hydroxybenzal) N'(4′-hydroxyphenyl) thiourea (HHPT) were synthesised and characterized using FT-IR, 1H-NMR and 13C-NMR analysis. The curing reactions were studied for the epoxy resin diglycidyl ether of bisphenol-A (DGEBA) using new curing agents along with the conventional aromatic diamine 4,4′-diamino diphenyl methane (DDM) for comparison purpose. The curing profiles of DDM, DATD and DATD/HHPT towards DGEBA were examined by Differential Scanning Calorimetry (DSC). Elastic modulus and thermal stability of the cured resins were evaluated using DMA and TGA analysis. When compared with DDM and DATD, the DATD/HHPT curing system accelerated the curing rate due to the presence of phenol molecules in the HHPT. Furthermore, the DATD/HHPT-cured epoxy resin demonstrated higher elastic modulus along with better thermal stability. 相似文献
Epoxy matrices are successfully used for structural strengthening in civil engineering applications by means of carbon fiber reinforced polymers (CFRPs). In the context of sustainable development, the aim of this study is to develop biobased epoxy matrices as an alternative to the traditional petroleum‐based epoxy matrices used in CFRPs. This study focuses on two biobased epoxy monomers: a diglycidyl ether of bisphenol A (DGEBA) and a sorbitol polyglycidyl ether (SPGE). These monomers are reacted with a biobased curing agent, a phenalkamine (PhA), derived from cardanol. After in‐depth characterization of the chemical structures of the three monomers, the reactivity of both systems, DGEBA‐PhA and SPGE‐PhA, is studied using differential scanning calorimetry and rheology. The properties of the networks are characterized via dynamic mechanical analysis and water uptake measurements for polymers with partial or full conversion of epoxy groups, which are obtained by crosslinking at room temperature or at high temperature, respectively. The results reveal that the two systems are good candidates for the preparation of green composite materials as they meet the requirements necessary for manufacturing composites in civil engineering applications. 相似文献
Macroporous epoxy monolith was prepared via chemically induced phase separation using diglycidyl ether of bisphenol A (DGEBA) as a monomer, 4,4′-diaminodiphenylmethane (DDM) as a curing agent, and epoxy soybean oil (ESO) as a solvent. The morphology of the cured systems after removal of ESO was examined using scanning electron microscopy, and the composition of epoxy precursors/solvent for phase inversion was determined. The phase-separation mechanism was deduced from the optic microscopic images to be spinodal decomposition. The pore structure of the cured monolith was controlled by a competition between the rates of curing and phase separation. The ESO concentration, content of curing agent, and the curing temperature constituted the influencing factors on the porous morphology. The average pore size increased with increasing ESO concentration, increasing curing temperature, and decreasing the content of curing agent. 相似文献