Micro- and nanostructural characterization of melamine-formaldehyde microcapsule shells using electron microscopy

RAMACHANDRAN DHANYA; RIVERO GUADALUPE; EGOAVIL, RICARDO; CAKIR SEDA; HAUFFMAN, TOM; CRABBÉ, AMANDINE; SCHRYVERS DOMINIQUE; HEIDARI, HAMED; DU PREZ FILIP E.; IDRISSI, HOSNI; KURTTEPELI, MERT; TERRYN, HERMAN

Lyon

Congreso; European Microscopy Congress; 2016

A systematic study has been carried out to compare the surface morphology, shell thickness, mechanicalproperties and binding behavior of melamine formaldehyde microcapsules of 5 to 30 μm diameter size withvarious amounts of core content by using scanning and transmission electron microscopy including electrontomography, in-situ nanomechanical tensile testing and electron energy-loss spectroscopy. It is found thatporosities are present at the outside surface of the capsule shell but not at the inner surface of the shell.Nano-mechanical tensile tests on the capsule shells reveal that the Young?s modulus of the shell material ishigher than that of bulk melamine formaldehyde and that the shells exhibit a larger fracture strain compared tothe bulk. Core-loss elemental analysis of microcapsules embedded in epoxy indicates that during the curingprocess, the microcapsule-matrix interface remains uniform and the epoxy matrix penetrates into the surfacemicroporosities of the capsule shells.