Curing under continuous microwaves (2 450 MHz) of thermosetting epoxy prepolymers: final statement

Alazard, Patrick; Palumbo, Michel; Gourdenne, Albert

doi:10.1002/masy.200350906

Cited by 6 publications

(3 citation statements)

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“…The reaction rate, cure time, and T g of microwave-cured epoxy have been reported to be dependent on the resin system (hardener/curing agents). 4,20,21 No microwave effect on the kinetics of epoxy curing and the three-dimensional structure has been proposed, 15,28 but some researchers have proposed rate enhancement by microwave curing. 9,18,27 Small changes in the mechanical properties of microwave-cured epoxy have been reported, 7,11 whereas increases and decreases in the tensile properties have been observed.…”

Section: Introductionmentioning

confidence: 99%

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

Tanrattanakul

Saetiaw

2005

J of Applied Polymer Sci

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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.

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Section: Introductionmentioning

confidence: 99%

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

Tanrattanakul

Saetiaw

2005

J of Applied Polymer Sci

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“…When the resin became too viscous in the early state of crosslinking process, flowability or diffusion of epoxy and hardener were lowered, which caused locally inhomogeneous structure. The viscosity effect, associated with the progress of the reaction, hindered more and more the Brownian motion and lowered the kinetics of curing 20. Viscosity of resins cured in the thermal oven and microwave oven at a certain period were measured.…”

Section: Resultsmentioning

confidence: 99%

Comparison between microwave and thermal curing of glass fiber–epoxy composites: Effect of microwave‐heating cycle on mechanical properties

Tanrattanakul

Jaroendee

2006

J of Applied Polymer Sci

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ABSTRACT:The objective of this study was to compare the mechanical properties between epoxy composites cured by thermal heating and microwave heating. Epoxy-anhydride resins reinforced with glass fiber were cured in a domestic microwave oven and in a thermal oven. Hardening agents included methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride. Microwave curing was carried out at various conditions, including 1-, 2-, and 3-step heating cycle, whereby each cycle employed different power level and time. Mechanical properties were tested according to ASTM standards. It is found that the microwave-cured composites produced mechanical properties as good as the thermally cured composites. The 2-and 3-step heating cycle used in the microwave curing process produced better mechanical properties higher than those obtained from the microwaved 1-step and thermally curing process. This is attributed to the slow increase in temperature during the beginning of the microwave curing process whereby the very low power level was applied in the first cycle of the multistep heating process. This affected the slower rate of viscosity increment, resulting in better wettability of the glass fiber with enhanced interfacial adhesion between the fibers and the resins. The viscosity of resins affected the homogeneity of the crosslinked structure.

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“…The suitability of microwave curing on polymers [6][7][8] and different composite systems 5,[9][10][11][12][13][14][15][16][17][18] was extensively studied. Besides the reduction in curing time, several studies reported increased mechanical properties of the microwave cured composites explained by a more homogeneous hardening and/or an increased interfacial strength.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of microwave cured glass fibre epoxy composites prepared by resin transfer moulding

Maenz

Mühlstädt

Bossert

2014

Journal of Composite Materials

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The aim of this study was to significantly reduce the curing time for glass fibre epoxy composites in industrial relevant dimensions without worsening of the mechanical properties. With the combination of microwave heating and resin transfer moulding (RTM), the time between filling the mould and demoulding the samples was reduced to only 1 h and 15 min compared to at least 6 h for conventional curing of the same material. Based on the different dielectric losses of cured and uncured resin a pulsed microwave process was developed. In this way homogenously cured samples were obtained. Tensile strength, flexural strength, flexural modulus of elasticity and Charpy impact strength of microwave cured samples were compared to conventionally cured samples. No statistically significant differences were found. Thus, microwave curing shows a high potential to improve the efficiency of fibre composite production while maintaining the mechanical properties.

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Curing under continuous microwaves (2 450 MHz) of thermosetting epoxy prepolymers: final statement

Cited by 6 publications

References 0 publications

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

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

Comparison between microwave and thermal curing of glass fiber–epoxy composites: Effect of microwave‐heating cycle on mechanical properties

Mechanical properties of microwave cured glass fibre epoxy composites prepared by resin transfer moulding

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