Addition of H3PO4 to diglycidyl ethers of bisphenol A: Kinetics and product structure (original) (raw)
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We have investigated the reactions of glycidyl ether, glycidyl ester and other oxirane functional resins with carboxyl or anhydride functional compounds and polymers in the presence of a wide range of amine, phosphonium and metal catalysts. We confirmed that both amine and phosphonium compounds can catalyze the reaction of epoxy groups with carboxyl and anhydride groups. There are certain deficiencies with these catalysts, such as a tendency to yellow and a reduction in stability at ambient or elevated temperatures. We also observed that many of the known amine catalysts contribute to poorer humidity resistance and exterior durability. Several metal salts were found to be effective catalysts, but they also contributed to a reduction in chemical resistance or they led to paint instability.
Epoxy Resins Chemical Modification by Dibasic Acids
Chemistry & Chemical Technology, 2014
Kinetic regularities of epoxy resins chemical modification by aliphatic and aromatic dibasic acids have been studied. The commercial dianic resins ED-20 and ED-24 were used as epoxy resins. Oxalic, malonic, succinic, sebacic, maleic, terephthalic and isophthalic acids were used as dibasic carboxylic acids. The effective rate constants and activation energies of the reactions between epoxy resin and acids by different nature have been calculated. The synthesis method for oligomers with epoxy and carboxy groups has been suggested. The structure of synthesized oligomers was confirmed by chemical analyses and IR-spectroscopy.
JCC 2017 38 1093 epoxy-acid.pdf
A comprehensive picture on the mechanism of the epoxycarboxylic acid curing reactions is presented using the density functional theory B3LYP/6-31G(d,p) and simplified physical molecular models to examine all possible reaction pathways. Carboxylic acid can act as its own promoter by using the OH group of an additional acid molecule to stabilize the transition states, and thus lower the rate-limiting barriers by 45 kJ/mol. For comparison, in the uncatalyzed reaction, an epoxy ring is opened by a phenol with an apparent barrier of about 107 kJ/ mol. In catalyzed reaction, catalysts facilitate the epoxy ring opening prior to curing that lowers the apparent barriers by 35 kJ/mol. However, this can be competed in highly basic catalysts such as amine-based catalysts, where catalysts can enhance the nucleophilicity of the acid by forming hydrogenbonded complex with it. Our theoretical results predict the activation energy in the range of 71 to 94 kJ/mol, which agrees well with the reported experimental range for catalyzed reactions.
Colloid and Polymer Science, 2003
This work examines the curing kinetics, thermal properties, and decomposition kinetics of diglycidyl ether of bisphenol A (DGEBA) epoxies with three different curing agents, 2-(6-oxido-6H-dibenz(c,e)(1,2)oxaphosphorin-6-yl)-1,4-naphthalenediol (ODOPN), bisphenol A (BPA), and bisphenol S (BPS). The differential scanning calorimetry curing study reveals that the curing kinetics of the DGEBA/ODOPN epoxy is first order, independent of the scan rate. The ODOPN-containing epoxy, unlike the conventional BPA one, includes a phosphorus-containing bulky pendant aromatic group and results in an increase in the glasstransition temperature of 83 K, the char yield increases by a factor of 3, and the limiting oxygen index values increase from 23 to 27. For the BPS system, the glass-transition temper
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.
Reaction kinetics of epoxy resin modified with reactive and nonreactive thermoplastic copolymers
Journal of Applied Polymer Science, 2009
An epoxy resin system based on a triglycidyl p-amino phenol (MY0510) was crosslinked using stoichiometric amounts of 4,4 0 -diaminodiphenyl sulfone. The epoxy was modified with random copolymers, polyethersulfone-poly(ether-ethersulfone) (PES:PEES), with either amine or chlorine end groups, at 10 and 20 wt %. The reaction kinetics for both unmodified and modified epoxy systems were studied using differential scanning calorimetry in isothermal and dynamic conditions. The results show that the degree of conversion in thermoplastic-modified epoxies at any reaction time is smaller compared with the unmodified resin. Gel point (GP) determination was done from rheological measurements. The modified system containing 20% of the PES:PEES additive showed considerable increase in the GP. The reaction rate shows the characteristic of an autocatalytic reaction where the product acts as catalyst. The activation energy, E a calculated from the isothermal reaction depends on the extent of conversion and increases with increasing PES:PEES content. For unmodified epoxy system, the average E a is 67.8 AE 4.1 kJ mol À1 but for systems modified with 20 wt % of amine and chlorine PES:PEES, the value increased to 74.1 AE 3.3 and 77.9 AE 4.4 kJ mol À1 , respectively. V
Cure mechanisms of diglycidyl ether of bisphenol A (DGEBA) epoxy with diethanolamine
Polymer, 2016
When diethanolamine (DEA) is used as a curative for a DGEBA epoxy, a rapid "adduct-forming" reaction of epoxide with the secondary amine of DEA is followed by a slow "gelation" reaction of epoxide with hydroxyl and with other epoxide. Through an extensive review of previous investigations of simpler, but chemically similar, reactions, it is deduced that at low temperature the DGEBA/DEA gelation reaction is "activated" (shows a pronounced induction time, similar to autocatalytic behavior) by the tertiary amine in the adduct. At high temperature, the activated nature of the reaction disappears. The impact of this mechanism change on the kinetics of the gelation reaction, as resolved with differential scanning calorimetry, infrared spectroscopy, and isothermal microcalorimetry, is presented. It is shown that the kinetic characteristics of the gelationreaction of the DGEBA/DEA system are similar to other tertiary-amine activated epoxy reactions and consistent with the anionic polymerization model previously proposed for this class of materials. Principle results are the time-temperature-transformation diagram, the effective activation energy, and the upper stability temperature of the zwitterion