Preparation and Study of Charge Transfer Complexes of N.N.N.N-Tetra-Methyl-Para-Phenylene-Diamine (TMPD) with NG, Tetryl, RDX and HMX

Charge transfer complexes of NG tetryl, RDX and HMX as electron acceptors with tetra-methyl-para-phenylene-diamine (TMPD) as electron donor were prepared and studied. When the solution of nitro-explosives in an inert solvent were added to a solution of TMPD, an intense violet colour was produced. This colour is due to the formation of TMPD cation known as Wurster radical formed from TMPD through the loss of an electron. It has been shown that one mole of each of NG, tetryl, RDX and HMX is needed to form oneTMPD cation. These complexes have also been studied by ultra-violet and infrared spectroscopy

Restructuring of colloidal aggregates in shear flow: Coupling interparticle contact models with Stokesian dynamics

A method to couple interparticle contact models with Stokesian dynamics (SD) is introduced to simulate colloidal aggregates under flow conditions. The contact model mimics both the elastic and plastic behavior of the cohesive connections between particles within clusters. Owing to this, clusters can maintain their structures under low stress while restructuring or even breakage may occur under sufficiently high stress conditions. SD is an efficient method to deal with the long-ranged and many-body nature of hydrodynamic interactions for low Reynolds number flows. By using such a coupled model, the restructuring of colloidal aggregates under stepwise increasing shear flows was studied. Irreversible compaction occurs due to the increase of hydrodynamic stress on clusters. Results show that the greater part of the fractal clusters are compacted to rod-shaped packed structures, while the others show isotropic compaction.Comment: A simulation movie be found at http://www-levich.engr.ccny.cuny.edu/~seto/sites/colloidal_aggregates_shearflow.htm