Cure kinetics of biphenyl epoxy resin system using latent catalysts

Abstract

ABSTRACT:The investigation of the cure kinetics of a biphenyl epoxy-phenol resin system with different kinds of latent catalysts was performed by differential scanning calorimetry using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order, activation energy, and rate constant were calculated and reported. The results indicated that the curing reaction of the biphenyl epoxy resin system in this experiment proceeded through an autocatalytic kinetic mechanism, irrespective of the kind of catalyst. The epoxy resin system with acid/diazabicycloundecene (DBU) salt as the latent catalyst showed a second overall reaction order; however, a third reaction order was represented for microencapsulated triphenylphosphine (TPP). The storage stability tests for these systems were performed, and a good shelf life was observed in the epoxy resin system with pyromellitic acid/DBU salt, trimellitic acid/DBU salt, and microencapsulated TPP as the latent catalyst.

Improvement of the thermal latency for epoxy-phenolic resins by novel amphiphatic imidazole catalysts

“…For DGEBA treated with carboxylic acid 4 and amphiphatic compound 5-9, however, Scheme II. Proposed mechanism of adduct formation for the cure diglycidylether of bisphenol A, (DGEBA, NPEK-114M) with the organic Lewis acid-base hybrid catalysts (4)(5)(6)(7)(8)(9). the viscosity of DGEBA retained almost constant at ~2,000 cp.…”

“…Commercial available starting materials were used as purchased. Diglycidylether of bisphenol A (DGEBA, NPEK-114M) was purchased form Nan Ya Plastics Co. 3-(2-Ethyl-4-methyl-imidazol-1-yl)-propionitrile (2E4MZ-CN, 2) and 2-ethyl-4-methylimidazole (2E4MZ, 1) were purchased form Shikoku Chemical Co. Histamine (3), 3-phenylpropanoic acid (4), and imidazole-4-acrylic acid (6) were purchased from Acoros Chemical Co. 2-Amino-3-phenylpropanoic acid (5) and 2-amino-3-(imidazole-4-yl)-propionic acid (8) were purchased from Novabiochem Co. 3-(Imidazole-4-yl)-propionic acid (7) and N-tert-butoxycarbonylhistidine (9) were prepared by reported procedure. 21,22 Synthesis of 3-(imidazol-4-yl)propionic Acid (7).…”

“…Thermal 11 and cationic latent 12 catalysts are two classes of catalysts developed to promote the pot-life of epoxy resin systems. Many cationic latent catalysts were published in recent year and their reactivity were enhanced by the couterions including BF 4 -, PF 6 -, AsF 6 -and SbF 6 ever, the acidic species (HBF 4 , HPF 6 , HAsF 6 and HSbF 6 ) would be released to damage the electronic products. Many pure thermal latent catalysts 14 were developed and reported as epoxy curing agents in the recent research because they can provide polymers of better heat resistance, lower tensile elongation, a higher modulus and a wider range of cure temperature than amine-cured system.…”

“…To improve the pot life at room temperature, latent catalysts are thus developed. 6 Catalysts are used in most molding compound formulations to reduce the in-mold time and extremely important for adhesives, paints, coating, molding resins, insulation materials, and matrices for composite materials. However, un-modified catalysts are less stable and the curing process occurs fast at room temperature.…”

“…Their excellent insulating characteristics, good adhesive properties, outstanding chemical resistance, retention of properties under severe operating conditions, low moisture adsorption, and absence of by-products causing void formation or acting as plasticizers attract attentions in the fields of industry and research. [1][2][3][4][5][6][7] As an epoxy resin, high molecular weight biphenyl type epoxy resins are highly reliable electronic molding compounds (EMC) with good adhesion and high toughness, and can be used as high filter loadings. [8][9][10] Nevertheless, the biphenyl type epoxy resins of low molecular weight show low storage stability at room temperature.…”