Michel Delmotte

Microwave effects in solvent-free esters aminolysis

Solvent-free ester aminolysis was studied under microwave or conventional heating either in the absence of base or induced by KOtBu with or without a phase transfer agent. The specific microwave effects were shown to be dependent on the conditions and discussed in terms of relative polarities of ground and transition states.

Kinetics modeling of a modified epoxy-amine formulation cured by thermal and microwave energy

The reaction kinetics of a rubber-modified epoxy formulation cured by microwave or thermal energy were investigated. Two phenomenological models were developed to predict the time and temperature dependence of the conversion for the neat and the modified systems. Good agreement was observed between the kinetic models and experimental results generated by chromatographic and calorimetric techniques. The same kinetic behavior was observed whatever the curing process (conventional or microwave heating).

Dielectric and geometric dependence of electric field and power distribution in a waveguide heterogeneously filled with lossy dielectrics

In microwave processing of dielectric materials which completely fill a waveguide, the distribution of the electric field within the material needs to be known. This paper presents the theoretical conditions for the microwave cure of large pieces, the size of which is more than the wavelength. The mathematical description of heterogeneously multilayer-filled waveguides presents certain difficulties because of the involved transcendental equations. A computer treatment to determine the electric-field spatial distribution is developed. The influence of the dielectric constants and the thickness of the dielectric materials on the spatial distribution of the electric field and power flow in each layer is studied. In particular, the field strength is enhanced in the dielectric with the highest permittivity. A numerical resolution of the transcendental equations defining the cutoff frequencies of propagation modes allows one to enumerate the modes, which can successively appear in a dielectric-loaded waveguide as functions of dielectric and geometric parameters. The attenuation constant and the microwave power dissipated in each material are determined. A balance sheet of energy is established.

Control of Attenuation in Microwaves Processing to Obtain Uniform Treatment of Epoxy Glass

Abstract This work deals with thermal aspect of the microwaves processing by applying the dielectric effect of attenuation inversion of electromagnetic wave as a solution for uniform treatment. Interest is devoted to the description of electromagnetic and chemical thermal contributions present during microwave heating of a thermosat material. An analytic methods was complemented with experimental data obtained by DSC. The chemical heat contribution is modeled by two methods: analytical and an experimental. The composite was characterized in terms of the reaction progress. The coupled electromagnetic, chemical and thermal model show results that can be evaluated from the temperature evolution. There is an strong rise in the temperature in one point, which is due to the non uniformity of the heat-storage capacity along the composite to be treated. The region of validation of the model is also shown.