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.

Three types of unsaturated polyester matrix, ortho phthalic, iso phthalic, and vinyl ester, reinforced with glass fiber laminated composite waste have been subjected to investigate thermal decomposition behavior and kinetic parameters using non-isothermal thermogravimetric analysis from an ambient to temperature 900°C under nitrogen atmosphere at the passing flow rate of 20 ml/min. The results showed that the major decomposition range of the unsaturated polyester matrix was from 260 to 445°C, depending on a heating rate and the different types of polyester matrix. Regarding their chemical structure, ortho phthalic polyester started to degrade at lower temperature (260-280°C) than iso phthalic and vinyl ester (300-350°C). The remaining solid residual contained glass fiber which could not degrade under experimental conditions. The maximum rate of weight loss was increased with increasing heating rate. The activation energy for decomposition of ortho, iso phthalic, and vinyl ester composites was 168, 172, and 176 KJ/mol, respectively.

Currently solid wastes generated from manufacturing process of thermosetting composite have caused environmental problems because they are non biodegradable product and cannot be recycled or remolded due to chemically crosslinked. Thus, the aim of this research is to convert glass fiber reinforced epoxy composite waste to fuel gases by gasification process. The composite waste was first grounded and its thermal decomposition behavior was then investigated using isothermal thermogravimetric analysis (TGA) from an ambient to 900°C at heating rate of 10°C/min under nitrogen atmosphere. The results showed that major decomposition temperatures of the epoxy matrix were ranging from 300 to 450°C. The composite sample was then mixed with two different catalysts, olivine (LiFePO4) or 10%NiAl2O3in order to study the effect of catalyst on gas conversion efficiency before it was gasified in a fixed bed reactor at final temperature of 500, 600, 700, and 800°C under nitrogen mixed with air at total flow rate of 200 mL/min. Gasification process indicated that solid residues were mainly brittle black containing residual glass fiber. The significant increasing of carbon monoxide and carbon dioxide conversion was achieved from sample mixed with olivine catalyst at gasification temperature of 700°C, when compared with result without catalyst at baseline conversion of 500°C as. Therefore, it can be expected that gasification process is a promising method to deal with epoxy composite for producing renewable energy.