Jocelyne Galy

Synthesis of cross-linked epoxy microparticles: Effect of the synthesis parameters

Epoxy crosslinked microparticles were synthesized from the reaction between diglycidyl ether of bisphenol A and a diamino hardener, through precipitation polymerization in a polypropylene glycol solvent. The influence of the monomer concentration, the amine/epoxy stoichiometric ratio, the reaction temperature and the structure of the diamine (aromatic or cycloaliphatic) were investigated, since these parameters may affect the structure and properties of the particles. Morphological analysis revealed that, in all cases, spherical particles were obtained with diameters ranging from 1 to 6 μm. The glass transition temperatures of the particles was found to vary between 130 and 160 °C using the aromatic diamine and between 116 and 141 °C using the cycloaliphatic diamine. It was also found that the effective stoichiometry of the particles was different from the initial stoichiometry in the feed solution.

Improving Adhesion Strength Analysis by the Combination of Ultrasonic and Mechanical Tests on Single-Lap Joints

The aim of this paper is to improve knowledge about adhesion strength in single-lap joints by the comparison of data from both nondestructive testing (NDT) and standard mechanical tests. This study presents a high-frequency ultrasonic imaging of aluminum–epoxy–aluminum joints that were carefully chemically prepared using two different surface treatments of the aluminum substrate: silanization and chromic–sulfuric etching. The surface energy of the treated substrate was measured. A complete set of ultrasonic data were obtained using high-frequency focused transducers. After ultrasonic inspection, single-lap shear tests were performed, and the mechanical strength of each joint was determined. The good correlations among the surface measurements, the mechanical tests, and the ultrasonic results are presented and discussed. The demonstration of a close correlation between the ultrasonic images obtained at high frequency and the fracture surface is promising.