A. K. Srivastava

KINETICS AND MECHANISM OF ESTERIFICATION OF MONOEPOXIES

ABSTRACT The esterification of monoepoxy diluents (phenyl, cresyl, and butyl glycidyl ethers) and acrylic acid in presence of triphenylphosphine as catalyst was performed at 70 ○, 75 ○, 80 ○, 85 ○, and 90 ○C, and it followed first-order kinetics. The reactivity of aromatic monoepoxies was found to be higher than aliphatic, due to the inductive effect of phenyl and butyl groups. The activation energy of the esterification of the monoepoxy increases as Pv < Cv < Bv and varies from 67 to 82 KJ/mole. The specific rate constants were found to obey the Arrhenius expression. The kinetic and thermodynamic parameters viz., activation energy, frequency factor, entropy, enthalpy, and free energy revealed that the reaction was spontaneous and irreversible, resulting in a highly ordered, activated complex. A suitable mechanism is proposed and discussed.

Synthesis of Vinyl Ester Resins in the Presence of Monoepoxies: A Kinetic Study

The synthesis of vinyl ester resins V1, V2, and V3 was carried out using bisphenol-A–based epoxy resin and acrylic acid in presence of phenyl, cresyl, butyl, and glycidyl ethers, respectively, as reactive diluent and triphenylphosphine as catalyst. The reaction was performed at 70°, 75°, 80°, 85°, and 90°C and it followed the first-order kinetics. The specific rate constants, calculated by the regression analysis, were found to obey Arrhenius expression. The kinetic and thermodynamic parameters activation energy, frequency factor, entropy, enthalpy, and free energy revealed that the reaction was spontaneous and irreversible with highly ordered activated complex. The activation energy of the esterification of epoxy resin in presence of monoepoxy diluents increases in this order: V1<V2<V3. The experimental results were explained by proposing a reaction mechanism and deriving the rate equation.

Synthesis and characterization of epoxy resins containing bismuth

The synthesis of epoxy resins in the presence of Bi as bismuth acrylate (BiA3) showed that the properties such as epoxide equivalent weight (eq/100 g), molecular weight, and viscosity (ηsp) increased; whereas hydrolyzable chlorine content, hydroxyl content, and refractive index decreased in the presence of BiA3. The metal forms a complex with ether linkage of epoxy resins, as evidenced from infrared spectroscopy. The presence of Bi in epoxy resins has been confirmed by scanning electron microscopy (SEM) and qualitative analysis. The glass transition temperature (Tg) of epoxy resins containing 1.18 × 10−5 and 2.8 × 10−5 molar equivalent of BiA3 is 131.58 and 190°C, respectively, and is greater than that of blank (130°C). The heat of reactions for epoxy resins containing 1.18 × 10−5 molar equivalent of BiA3, calculated by differential scanning calorimetry, is 4.75 J g.

Synthesis, Reactions, and Properties of Modified Epoxy Resins

Abstract The chemistry of epoxy resins is at the present time one of the most vigorously developing branches of polymer chemistry. The rapid rate of its development can be accounted for by the fact that approximately 90 research articles have appeared in polymer journals during the last 10 years. Epoxy resins in one form or another comprise a significant fraction of the literature on step growth polymerization. The synthesis of new epoxy resins and the detailed investigation of the mechanisms and their characteristics have been directed toward the production of improved products of this type.

Effect of Incomplete d Orbital on the Epoxy Resins Properties: Synthesis and Characterization

Abstract The theoretical generalization of the experimental results, to investigate the effect of incomplete d orbital, using nickel acrylate (NiA2) on the epoxy resins properties is repoted. The value(s) of epoxide equivalent, hydroxyl content, hydrolyzable chlorine content, specific gravity, refractive index of epoxy resins have been evaluated. DSC data have been used to determine the order of reaction, heat of reaction, activation energy & glass transition temperature (Tg). The epoxy resins, cured with pyridinium dicyano methylide (PDMY), as a new curing agent, showed improved chemical resistance, flexibility and electrical conductivity.