Curing and pyrolysis of epoxy resins containing 2-(6-oxido-6H-dibenz(c,e)(1,2)oxaphosphorin-6-yl)-1,4-naphthalenediol or bisphenol S (original) (raw)
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Preparation, curing kinetics, and thermal properties of bisphenol fluorene epoxy resin
Journal of Applied Polymer Science, 2007
Diglycidyl ether of 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) was synthesized to introduce more aromatic structures into an epoxy resin system. The structure of DGEBF was characterized with Fourier transform infrared and 1 H-NMR. 4,4 0 -Diaminodiphenylmethane (DDM) was used as the curing agent for DGEBF, and differential scanning calorimetry was applied to study the curing kinetics. The glass-transition temperature of the cured DGEBF/DDM, determined by dynamic mechanical analysis, was 2608C, which was about 1008C higher than that of widely used diglycidyl ether of bisphenol A (DGEBA). Thermogravimetric analysis was used to study the thermal degradation behavior of the cured DGEBF/ DDM system: its onset degradation temperature was 3708C, and at 7008C, its char yield was about 27%, whereas that of cured DGEBA/DDM was only 14%.
Curing and thermal behavior of epoxy resins of hexafluoro - bisphenol –A and bisphenol-A
Polímeros, 2016
This paper describes the synthesis and characterization of epoxy resins based on (hexafluoroisopropylidene)diphenol (EFN) and p,p'-isopropylidenebisphenol (EBN), respectively and 4, 4'-(hexafluoroisopropylidene)dipthalic-imideamine (IMAM), a curing agent. The synthesized epoxy resins and IMAM curing agent were characterized by Fourier Transform Infrared (FTIR) and 1 H Nuclear Magnetic Resonance (NMR) spectroscopy. 13 C NMR technique was also used to characterize IMAM. Study of curing behavior of EFN and EBN with stoichiometric amount of aromatic 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylsulfone (DDS) and IMAM by using Differential Scanning Calorimetery (DSC) indicated that IMAM was least reactive curing agent towards both epoxy resins as compared to DDS and DDM. The investigation of thermal decomposition of the cured compounds by thermogravimetric analyzer (TGA) indicated the higher thermal stability of EFN and EBN resins initially with DDS and at elevated temperatures with IMAM. It was also observed that EFN resins were thermally more stable than EBN resins cured with corresponding curing agents.
Effect of structure on thermal behaviour of epoxy resins
European Polymer Journal, 2003
The paper deals with the curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) using three novel multifunctional aromatic amines having phosphine oxide and amide-acid linkages. The amines were prepared by reacting tris(3-aminophenyl)phosphine oxide (TAP) with 1,2,4,5-benzenetetracarboxylic acid anhydride (P)/4,4 0-(hexafluoroisopropylidene)diphthalic acid anhydride (F)/3,3 0 ,4,4 0-benzophenonetetracarboxylic acid dianhydride (B). Amide-acid linkage in these amines is converted to thermally stable imide linkage during curing reaction. Curing temperatures of DGEBA were higher with phosphorylated amines than the conventional amine 4,4 0-diamino diphenyl sulphone (D). A decrease in initial decomposition temperature and higher char yields were observed when phosphorus containing amide-acid amines were used as curing agents for DGEBA.
Iran Polym J, 2008
A sulphone-nitrogen containing heterocyclic ring, tetraphenylthiophene diamine (TPTDA) was prepared and used as curing agent together with triphenylphosphine (PPh 3) to cure diglycidyl ether of a bisphenol A-based epoxy resin (DGEBA). Activation energies (E a) for curing DGEBA/TPTDA and DGEBA/ TPTDA/PPh 3 systems by using DSC data and Kissinger equation are 66.6 kJ/mol and 76.6 kJ/mol, respectively. The increase in E a can be due to polymerization of DGEBA by PPh 3 and formation of larger molecules with reduced mobility before curing with TPTDA to start. E a of thermal degradation of cured DGEBA/TPTDA and DGEBA/TPTDA/PPh 3 systems by using TGA data and Horowitz-Metzger equation are 56.0 kJ/mol and 128.0 kJ/mol, respectively. The onset decomposition temperature and the char yield have increased from 230ºC to 320ºC and from 21.4% to 32.5% for the above systems, respectively. The addition of PPh 3 to the curing mixture enhanced char formation and improved thermal stability of the resin.
Journal of Thermal Analysis and Calorimetry, 2010
A new homologous series of curing agents (LCECAn) containing 4,4 0-biphenyl and n-methylene units (n = 2, 4, 6) were successfully synthesized. The curing behaviors of a commercial diglycidyl ether of bisphenol-A epoxy (E-51) and 4,4 0-bis(2,3-epoxypropoxy)biphenyl (LCE) by using LCECAn as the curing agent have been investigated by differential scanning calorimetry (DSC), respectively. The Ozawa equation was applied to the curing kinetics based upon the dynamic DSC data, and the isothermal DSC data were fitted using an autocatalytic curing model. The glass transition temperatures (T g) of the cured epoxy systems were determined by DSC upon the second heating, and the thermal decomposition temperatures (T d) were obtained by thermogravimetric (TG) analyses. The results show that the number of methylene units in LCECAn has little influence on the curing temperatures of E-51/LCECAn and LCE/LCECAn systems. In addition, the activation energies obtained by the dynamic method proved to be larger than those by the isothermal method. Furthermore, both the T g and T d of the cured E-51/LCECAn systems and LCE/LCECAn systems decreased with the increase in the number of methylene units in LCECAn.
Journal of Applied Polymer Science, 2009
This article describe the influence of phenolphthalein poly (ether ketone) (PEK-C) on the cure behaviors and thermal properties of the diglycidyl ether of bisphenol A (DGEBA) epoxy resin with cyanate ester as curing agent. The curing kinetics and reaction pathways were monitored using dynamic differential scanning calorimeter and Fourier transform infrared spectroscopy. The dependence of activation energy on the conversion degree for all the studied systems was calculated in the light of Ozawa-Flynn-Wall method. Furthermore, the thermomechanical properties and the thermal stability of the cured resins were also evaluated by dynamic mechanical analysis and thermogravimetric analysis, respectively. Conclusions can be drawn as follows: the main reaction pathways did not vary with the inclusion of PEK-C, but the reaction rate of the blend was found to be higher than that of the neat epoxy. The glass transition temperature of the blend was not changed by the addition of PEK-C, while the initial decomposition temperature slightly decreased with increase in PEK-C content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polymer Journal, 2007
Three bisphenol-A based novolac epoxy resins with different bridging groups: methylene, methinephenyl and methine-naphthyl, respectively, between bisphenol-A phenyl rings were prepared to study the effect of structure of bridging group on curing and properties of the epoxy resins. The structures of the obtained epoxy resins were characterized using FT-IR and 1 H NMR spectra, the molecular weight and polydispersity index were determined using GPC. The effect of bridging groups on the curing kinetics, thermal mechanical properties, thermal stability, and moisture resistance of the synthesized epoxy resins cured with 4,4 0 -diaminodiphenyl sulphone (DDS) were investigated by dynamic differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, X-ray diffraction and moisture absorption measurement. It was concluded that the methylene-bridged epoxy resin possessed the highest curing reaction reactivity toward DDS and the methine-naphthyl-bridged epoxy network possessed the highest storage modulus, glass transition temperatures, thermal stability, and moisture resistance.
Curing and pyrolysis of cresol novolac epoxy resins containing BABODOPN
Polymer Engineering & Science, 2005
This work investigates the curing kinetics, thermal stability, flammability, and decomposition kinetics of cresol novolac epoxy (CNE) cured with two curing agents, [1,4bis(3-aminobenzoyloxy)-2-(6-oxido-6h-dibenz(c,e)(1,2) oxaphosphorin-6-yl)-naphthalene] (BABODOPN) and diamino diphenyl methane (DDM). The DSC curing study shows that the activation energy (E a) can be estimated by Kissinger's method and the E a of CNE/DDM, 54.3 KJ/mole, is one-half that of CNE/BABODOPN, 112.6 KJ/ mole; also, the glass transition temperature (T g) of the latter, 479.5 K, is substantially higher than that, 383 K, of the former. Both increases are attributed to the incorporation of phosphorus-containing a bulky pendant aromatic group into the BABODOPN molecule, which inhibits its mobility. In comparison with the conventional DDM system, the phosphorus-nitrogen synergistic effect of BABODOPN improves the limiting oxygen index (LOI) from 26 to 47, and increases the char yield from 30.4% to 38.3%. Moreover, the CNE/BABODOPN system even exhibits better flame retardancy than the excellent CNE/ODOPN system, developed by the authors previously, because of the synergistic effect. Finally, the investigation of thermal gravimetric analysis (TGA) decomposition in N 2 by Ozawa's method demonstrates that the mean E a declines as the phosphorus content increases, because the ease of decomposition of the phosphorus in the initiation stage facilitates the formation of an insulating layer.
Journal of Applied Polymer Science, 2017
A novolac epoxy resin based on 4,4 0-dihydroxybenzophenone (BZPNE) was synthesized via epoxidation of 4,4 0-dihydroxybenzophenone novolac resin (BZPN). BZPN was obtained by strong mineral acid catalyzed reaction of 4,4 0-dihydroxybenzophenone (BZP) and paraformaldehyde. The formation of BZPNE and BZPN was confirmed by Fourier transform infrared spectroscopy, proton and carbon nuclear magnetic resonance spectroscopy, gel permeation chromatography, and epoxy equivalent weight. Different blends of BZPNE with diglycidyl ether of bisphenol-A (DGEBA; EEW $180) were cured using dicyandiamide were characterized by thermogravimetric analysis, thermomechanical analysis, dynamic mechanical analysis, and interfacial property between aluminum adherends at ambient and elevated temperature. Thermal properties were found to improve on increasing quantity of BZPNE in DGEBA as it is evidenced from glass transition temperature (T g). Likewise, no deterioration in interfacial properties was observed with the highest quantity of BZPNE (30%) in DGEBA blend, when tested at 150 8C. Cure kinetics of compositions were studied by nonisothermal differential scanning calorimetry and Kissinger method was used to compute the kinetic parameters such as frequency factor (A), activation energy (E a) followed by the dependency of rate constant (k) on temperature of different blends. V
Phosphorus-containing epoxy resins: Thermal characterization
Journal of Applied Polymer Science, 2002
Three novel aromatic phosphorylated diamines, i.e., bis N, methyl phosphinoyl] phenyl} pyromellitamic acid (AP), 4,4Ј-oxo bis N, methyl phosphinoyl] phenyl}phthalamic acid (AB) and 4,4Ј-hexafluoroisopropylidene-bis N, methyl phosphinoyl] phenyl}phthalamic acid (AF) were synthesized and characterized. These amines were prepared by solution condensation reaction of bis(3-aminophenyl)methyl phosphine oxide (BAP) with 1,2,4,5-benzenetetracarboxylic acid anhydride (P)/3,3Ј,4,4Ј-benzophenonetetracarboxylic acid dianhydride (B)/4,4Ј-(hexafluoroisopropylidene)diphthalic acid anhydride (F), respectively. The structural characterization of amines was done by elemental analysis, DSC, TGA, 1 H-NMR, 13 C-NMR and FTIR. Amine equivalent weight was determined by the acetylation method. Curing of DGEBA in the presence of phosphorylated amines was studied by DSC and curing exotherm was in the temperature range of 195-267°C, whereas with conventional amine 4,4Ј-diamino diphenyl sulphone (D) a broad exotherm in temperature range of 180 -310°C was observed. Curing of DGEBA with a mixture of phosphorylated amines and D, resulted in a decrease in characteristic curing temperatures. The effect of phosphorus content on the char residue and thermal stability of epoxy resin cured isothermally in the presence of these amines was evaluated in nitrogen atmosphere. Char residue increased significantly with an increase in the phosphorus content of epoxy network.