The Experts below are selected from a list of 8619 Experts worldwide ranked by ideXlab platform
He Pingsheng - One of the best experts on this subject based on the ideXlab platform.
-
Cure Behavior of epoxy resin e51 melamine phosphate mp methpa 2 4 emi halogen free fire retardant composite by the dynamic torsional vibration method
Journal of Composite Materials, 2006Co-Authors: Cheng Yiyun, He PingshengAbstract:The Cure Behavior of epoxy resin E51–melamine phosphate (MP)–methyltetrahydrophthalic anhydride (MeTHPA)–2-ethyl-4-methyl-imidazole (2,4-EMI) halogen-free fire retardant composite at varying temperatures and MP loading is investigated by the dynamic torsional vibration method (DTVM). The dynamic parameters, such as gelation time tg, apparent activation energy Ea, and curing rate k are estimated as well. The theoretical prediction is in good agreement with the experimental results obtained by the DTVM. The results show that the rate of Cure reactions depends distinctly on the Cure temperature. At low MP loadings, the tg for the systems does not change obviously, while at higher MP loadings, it has a remarkable increase. Furthermore, the Flory's gelation theory and the Avrami equation are used to describe the Cure Behavior of the halogen-free fire retardant composite system.
-
Cure Behavior of epoxy resin/CdS/2,4-EMI nanocomposites investigated by dynamic torsional vibration method (DTVM)
Polymer Bulletin, 2006Co-Authors: Yao Yuan, Chen Dazhu, He Pingsheng, Yang HaiyangAbstract:Epoxy resin/CdS nanocomposite was prepared by a novel method and its Cure Behavior was investigated by the HLX-II Resin Curemeter based on the dynamic torsional vibration method (DTVM). The non-equilibrium thermodynamic fluctuation theory, the Avrami equation and the Flory’s gelation theory have been used to analysis the Cure Behavior of the composite systems with different CdS and Cure agent loadings at various temperatures. The results show that the addition of CdS nanoparticles reduces the gel time tg, but has little effect on the mechanism of the Cure reaction. The theoretical prediction is in good agreement with the experimental results. The Avrami exponent of n decreases a little when the temperature increases.
-
Cure Behavior of epoxy resin cds 2 4 emi nanocomposites investigated by dynamic torsional vibration method dtvm
Polymer Bulletin, 2006Co-Authors: Yao Yuan, Chen Dazhu, He Pingsheng, Yang HaiyangAbstract:Epoxy resin/CdS nanocomposite was prepared by a novel method and its Cure Behavior was investigated by the HLX-II Resin Curemeter based on the dynamic torsional vibration method (DTVM). The non-equilibrium thermodynamic fluctuation theory, the Avrami equation and the Flory’s gelation theory have been used to analysis the Cure Behavior of the composite systems with different CdS and Cure agent loadings at various temperatures. The results show that the addition of CdS nanoparticles reduces the gel time tg, but has little effect on the mechanism of the Cure reaction. The theoretical prediction is in good agreement with the experimental results. The Avrami exponent of n decreases a little when the temperature increases.
-
Behavior of polyamidoamine dendrimers as curing agents in bis‐phenol A epoxy resin systems
Polymer International, 2005Co-Authors: Cheng Yiyun, Chen Dazhu, Fu Rongqiang, He PingshengAbstract:Polyamidoamine (PAMAM) dendrimers with different generations (0–5) were investigated as curing agents in epoxy resin systems. Flory's gelation theory and the Avrami equation were used to predict the Cure Behavior of epoxy resin/PAMAM/imidazole at various temperatures and PAMAM concentrations. The theoretical prediction is in good agreement with the experimental results obtained from the dynamic torsional vibration method. Copyright © 2004 Society of Chemical Industry
-
Cure Behavior of epoxy resin montmorillonite 2 ethyl 4 methylimidazole nanocomposite
Journal of Composite Materials, 2003Co-Authors: Chen Dazhu, He PingshengAbstract:Understanding of the mechanism and kinetics of Cure for polymer-layered silicate nanocomposites is now the interest of research. The objective of this investigation is to determine the effects of polymer-layered silicate on the Cure kinetics of an epoxy resin. The Cure process of epoxy resin-organo-montmorillonite (Org-MMT)-2-ethyl-4-methylimidazole (2,4-EMI) nanocomposite with different Org-MMT loadings was in situ monitored with a technique of dynamic torsional vibration method (DTVM) in the isothermal mode. The gel time tg and the completed Cure time tc can be read directly from the isothermal Cure curve, and the results show that the addition of Org-MMT reduces the tg and increases the rate of curing reaction. The apparent activation energy Ea of Cure reaction was estimated by the nonequilibrium thermodynamic fluctuation theory as well. With increasing of Cure temperature, the tg decreased and correspondingly, the Cure rate was accelerated. In addition, the theoretical prediction was in good agreement...
Chen Dazhu - One of the best experts on this subject based on the ideXlab platform.
-
Cure Behavior of epoxy resin/CdS/2,4-EMI nanocomposites investigated by dynamic torsional vibration method (DTVM)
Polymer Bulletin, 2006Co-Authors: Yao Yuan, Chen Dazhu, He Pingsheng, Yang HaiyangAbstract:Epoxy resin/CdS nanocomposite was prepared by a novel method and its Cure Behavior was investigated by the HLX-II Resin Curemeter based on the dynamic torsional vibration method (DTVM). The non-equilibrium thermodynamic fluctuation theory, the Avrami equation and the Flory’s gelation theory have been used to analysis the Cure Behavior of the composite systems with different CdS and Cure agent loadings at various temperatures. The results show that the addition of CdS nanoparticles reduces the gel time tg, but has little effect on the mechanism of the Cure reaction. The theoretical prediction is in good agreement with the experimental results. The Avrami exponent of n decreases a little when the temperature increases.
-
Cure Behavior of epoxy resin cds 2 4 emi nanocomposites investigated by dynamic torsional vibration method dtvm
Polymer Bulletin, 2006Co-Authors: Yao Yuan, Chen Dazhu, He Pingsheng, Yang HaiyangAbstract:Epoxy resin/CdS nanocomposite was prepared by a novel method and its Cure Behavior was investigated by the HLX-II Resin Curemeter based on the dynamic torsional vibration method (DTVM). The non-equilibrium thermodynamic fluctuation theory, the Avrami equation and the Flory’s gelation theory have been used to analysis the Cure Behavior of the composite systems with different CdS and Cure agent loadings at various temperatures. The results show that the addition of CdS nanoparticles reduces the gel time tg, but has little effect on the mechanism of the Cure reaction. The theoretical prediction is in good agreement with the experimental results. The Avrami exponent of n decreases a little when the temperature increases.
-
Behavior of polyamidoamine dendrimers as curing agents in bis‐phenol A epoxy resin systems
Polymer International, 2005Co-Authors: Cheng Yiyun, Chen Dazhu, Fu Rongqiang, He PingshengAbstract:Polyamidoamine (PAMAM) dendrimers with different generations (0–5) were investigated as curing agents in epoxy resin systems. Flory's gelation theory and the Avrami equation were used to predict the Cure Behavior of epoxy resin/PAMAM/imidazole at various temperatures and PAMAM concentrations. The theoretical prediction is in good agreement with the experimental results obtained from the dynamic torsional vibration method. Copyright © 2004 Society of Chemical Industry
-
Cure Behavior of epoxy resin montmorillonite 2 ethyl 4 methylimidazole nanocomposite
Journal of Composite Materials, 2003Co-Authors: Chen Dazhu, He PingshengAbstract:Understanding of the mechanism and kinetics of Cure for polymer-layered silicate nanocomposites is now the interest of research. The objective of this investigation is to determine the effects of polymer-layered silicate on the Cure kinetics of an epoxy resin. The Cure process of epoxy resin-organo-montmorillonite (Org-MMT)-2-ethyl-4-methylimidazole (2,4-EMI) nanocomposite with different Org-MMT loadings was in situ monitored with a technique of dynamic torsional vibration method (DTVM) in the isothermal mode. The gel time tg and the completed Cure time tc can be read directly from the isothermal Cure curve, and the results show that the addition of Org-MMT reduces the tg and increases the rate of curing reaction. The apparent activation energy Ea of Cure reaction was estimated by the nonequilibrium thermodynamic fluctuation theory as well. With increasing of Cure temperature, the tg decreased and correspondingly, the Cure rate was accelerated. In addition, the theoretical prediction was in good agreement...
-
Cure Behavior of epoxy resin montmorillonite imidazole nanocomposite by dynamic torsional vibration method
European Polymer Journal, 2003Co-Authors: Xu Weibing, He Pingsheng, Chen DazhuAbstract:Flory’s gelation theory, the non-equilibrium thermodynamic fluctuation theory and the Avrami equation have been used to predict the Cure Behavior of epoxy resin/organo-montmorillonite (Org-MMT)/imidazole intercalated nanocomposites at various temperatures and Org-MMT loadings. The theoretical prediction is in good agreement with the experimental results obtained by a dynamic torsional vibration method. The results show that the addition of Org-MMT reduces the gelation time tg and increases the rate of the curing reaction, the value of the kinetic constant k. The half-time t1/2 of Cure after the gel point decreases with increasing of Cure temperature, and the value of n is around 3 at lower temperature (<90 °C) and decreases to ∼2 as the temperature increases. The addition of Org-MMT has no obvious effect on the apparent activation energy of the Cure reaction. There is no special curing process required for the formation of an epoxy resin/Org-MMT/imidazole intercalated nanocomposite.
Joonwon Bae - One of the best experts on this subject based on the ideXlab platform.
-
thiol ene hyperbranched polymer hybrid thin films Cure Behavior and gas barrier properties
Journal of Non-crystalline Solids, 2011Co-Authors: Joonwon Bae, Yooseong YangAbstract:Abstract In this work, novel thiol-ene (TE)/hyperbranched polymer(HBP) hybrid thin films have been prepared by a simple photopolymerization method and the TE/HBP system was also investigated in terms of thermocuring Behavior and gas barrier properties. The effect of added HBP on thermal curing (cross-linking) of TE polymer was examined with dynamic and isothermal differential scanning calorimeter (DSC) and compared with photocuring reaction of identical system. The structure of prepared TE/HBP hybrid thin film was analyzed by X-ray diffraction (XRD). Themomechanical analysis (TMA) provided extensive data on the coefficient of linear thermal expansion (CTE), dimensional change upon heating, and isothermal profile of TE/HBP hybrid thin films. Light transmittance as well as water/oxygen permeability of the resulting TE/HBP hybrid thin film was also measured depending on the HBP content.
-
Thiol-ene/hyperbranched polymer hybrid thin films: Cure Behavior and gas barrier properties
Journal of Non-crystalline Solids, 2011Co-Authors: Joonwon Bae, Yooseong YangAbstract:Abstract In this work, novel thiol-ene (TE)/hyperbranched polymer(HBP) hybrid thin films have been prepared by a simple photopolymerization method and the TE/HBP system was also investigated in terms of thermocuring Behavior and gas barrier properties. The effect of added HBP on thermal curing (cross-linking) of TE polymer was examined with dynamic and isothermal differential scanning calorimeter (DSC) and compared with photocuring reaction of identical system. The structure of prepared TE/HBP hybrid thin film was analyzed by X-ray diffraction (XRD). Themomechanical analysis (TMA) provided extensive data on the coefficient of linear thermal expansion (CTE), dimensional change upon heating, and isothermal profile of TE/HBP hybrid thin films. Light transmittance as well as water/oxygen permeability of the resulting TE/HBP hybrid thin film was also measured depending on the HBP content.
-
Cure Behavior of the liquid crystalline epoxy carbon nanotube system and the effect of surface treatment of carbon fillers on Cure reaction
Macromolecular Chemistry and Physics, 2002Co-Authors: Joonwon Bae, Jyongsik Jang, Seong Ho YoonAbstract:The FT-IR spectra of carbon nanotubes (CN) and oxidated carbon nanotubes were obtained using diffuse reflection Fourier-transform infrared (DRIFT) spectroscopy. The Cure Behavior of the liquid-crystalline epoxy (LCE)/CN and the LCE/carbon black (CB) systems were investigated. The effect of surface treatment of the carbon nanotube on the Cure Behavior in the LCE/CN system was investigated with differential scanning calorimetry (DSC), and was compared with those of the CB. The heat of Cure in the LCE/CN system was higher than that in the LCE/CB system. The activation energy was dependent on the concentration of the curing agent. The activation energies for the Cure reaction were decreased as a result of surface treatment of carbon materials. It was possible to promote the curing reaction by the surface treatment of the carbon nanotube without decreasing the heat of Cure. The isothermal kinetic parameters were obtained from the Kamal equation. TEM images of carbon nanotube: carbon nanotube bundle.
Kai Yang - One of the best experts on this subject based on the ideXlab platform.
-
fabrication morphology and Cure Behavior of triethylenetetramine grafted multiwalled carbon nanotube epoxy nanocomposites
Polymer Journal, 2009Co-Authors: Kai YangAbstract:Multiwalled carbon nanotubes (MWCNTs) were first treated by a 3:1 (v/v) mixture of concentrated H2SO4/HNO3, and then triethylenetetramine (TETA) grafting was carried out. X-Ray photoelectron spectroscopy and Raman spectroscopy analyses proved the effectiveness of this kind of chemical functionalization method. The TETA thin layer was formed on the MWCNT surface, which contributes to good dispersion of MWCNTs in epoxy matrix. Cure Behaviors of MWCNT/epoxy systems were studied with non-isothermal differential scanning calorimetry. MWCNTs have the retarding effect on the Cure reaction owing to their steric hindrance, while TETA functional groups on the MWCNT surface can accelerate the primary amine-epoxide reaction and weaken the inhibition effect on the process of Cure. A qualitative analysis of the degree of vitrification in different epoxy systems was performed. The activation energy of the Cure reactions was obtained by the Flynn-Wall-Ozawa method.
-
Cure Behavior and thermal stability analysis of multiwalled carbon nanotube epoxy resin nanocomposites
Journal of Applied Polymer Science, 2008Co-Authors: Kai Yang, Yanping JinAbstract:As-received multiwalled carbon nanotubes (MWCNTs) were first treated by a 3 : 1 (v/v) mixture of concentrated H2SO4/HNO3 and further functionalized by ethylenediamine/dicyclohexylcarbodiimide/tetrahydrofuran solution. MWCNT/epoxy nanocomposites were prepared. Their Cure Behaviors were investigated by dynamic differential scanning calorimetry. Quantitative analysis of the activation energy as a function of the degree of curing was carried out by the Flynn-Wall-Ozawa method. The fitted multiple regression equations for values of the activation energy of different systems were obtained. MWCNTs have the retardation effect on the Cure reaction of epoxy resin, while the functional groups on the surface of amine-modified MWCNTs could accelerate the Cure reactions. Thermal stability was studied by thermogravimetric analysis. The filling of amine-modified MWCNTs is beneficial to lower the Cure activation energy and improve thermal stability of the nanocomposite. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
-
influence of surface treated multi walled carbon nanotubes on Cure Behavior of epoxy nanocomposites
Composites Part A-applied Science and Manufacturing, 2008Co-Authors: Kai Yang, Yanping Jin, Xifeng PanAbstract:The influence of surface treated multiwalled carbon nanotubes (MWCNTs) on the Cure Behavior of a bisphenol-A glycidol ether epoxy resin/2-ethyl-4-methylimidazole system was investigated with non-isothermal differential scanning calorimetry. With the increase of the MWCNT content, the initial curing temperature, exothermic peak temperature and Cure reaction activation energy first increase and subsequently decrease. The addition of MWCNTs results in a continuous increase in the degree of vitrification in the epoxy system, so that the Cure reaction is likely to be diffusion controlled at lower heating rate and larger conversion fractions.
Demin Jia - One of the best experts on this subject based on the ideXlab platform.
-
Cure Behavior of unsaturated polyester modified montmorillonite nanocomposites
Polymer International, 2007Co-Authors: Yan Zhou, Xiaoyun Yang, Demin JiaAbstract:Dynamic rheology, differential scanning calorimetry and in situ Fourier transform infrared spectroscopy were used to study the Cure Behavior of unsaturated polyester/modified montmorillonite nanocomposites. The results showed that their gel times increased markedly at the same Cure temperature, and that the activation energy of the nanocomposites was higher than that of the pure unsaturated polyester. Their peak temperatures of enthalpy increased as well. The total exotherm of the Cure reaction declined and the Cure rate decreased. In the curing process of pure unsaturated polyesters, the conversion of styrene was higher than that of the double bonds on unsaturated polyester macromolecular chains. The Cure mechanism of the unsaturated polyester/modified montmorillonite changed because of the presence of double bonds in the layers of modified montmorillonite. However, the conversion of styrene in the nanocomposites was lower than that of double bonds on unsaturated polyester chains during Cure at room temperature, and the conversion of styrene was increased after post-curing and was higher than that of the double bonds on unsaturated polyester chains at the end of the Cure reaction. Moreover, the degree of reaction of double bonds on unsaturated polyester chains of the nanocomposites was higher than that of unsaturated polyesters. Copyright © 2006 Society of Chemical Industry
