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

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

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.