Comparison of microwave and thermal cure of epoxy–anhydride resins: Mechanical properties and dynamic characteristics

Abstract

ABSTRACT:The objective of this work was to compare the mechanical properties of epoxy resins cured by thermal heating and microwave heating. Epoxy-anhydride (100:80) resins were cured in a domestic microwave oven and in a thermal oven. The hardening agents included methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride. Three types of accelerators were employed. Thermal curing was performed at 150°C for 20 and 14 min for resins containing 1 and 4% accelerator, respectively. Microwave curing was carried out at a low power (207 or 276 W) for 10, 14, and 20 min. All cured resins were investigated with respect to their tensile properties, notched Izod impact resistance, and flexural properties (three-point bending) according to ASTM standards. The tan ␦ and activation energy values were investigated with dynamic mechanical thermal analysis, and the extent of conversion was determined with differential scanning calorimetry. The differences in the mechanical properties of the thermally cured and microwavecured samples depended on the resin formulation and properties. Equivalent or better mechanical properties were obtained by microwave curing, in comparison with those obtained by thermal curing. Microwave curing also provided a shorter cure time and an equivalent degree of conversion. The glass-transition temperatures (tan ␦) of the thermally and microwave-cured resins were comparable, and their activation energies were in the range of 327-521 kJ/mol.

Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study

“…Since microwaves are of long wavelength, the energy penetrates deeper than ultraviolet or electron-beam irradiation [19]. Further it has many remarkable advantages over conventional heating such as, enhanced reaction rate, higher chemical yield, uniform processing, short reaction time, economically very cheap and clean.…”

Comparison of microwave absorption properties between BaTiO3/Epoxy and NiFe2O4/Epoxy composites

“…However, epoxy resins are one of the most important candidate thermoset due to having excellent electrical insulators, surface coatings, adhesives, and fiber‐reinforced composites. There have been key interests in the area of electromagnetic interference shielding and microwave absorption for epoxy resins, including epoxy–amine systems and epoxy–anhydride systems . L. A. Ramajo et al has reported that, epoxy resins are excellent insulator and protect component from short circuiting.…”

Processing and Characterization of Composites Curing by Microwave Irradiation

“…Especially in the case of composites employing thermosetting resins such as epoxy resin, insofar as the curing reaction occurs, the absorption capacity of the microwave, and its conversion into heat, decays considerably. [1] The microwaves are emitted and, as a reflection of the same in the furnace are formed several resonance modes with different points of maxima and minima, resulting in several hot spots, as the intensity of emitted energy. In this work, the heating profiles of these hot and cold spots were studied by infrared thermal images of composites based on glass fiber and epoxy.…”