Hierarchical Multi-stomatal Spherical Drug Preparation, Characterization And Performance Study

A new type of layered spherical propellant grain with a dense shell and a porous core(LPBP) was designed on the basis of interior ballistics and combustion theories in order to improve the performance in domestic ammunition of small arms. Both the shell and the core of LPBP were made out of the same component. Two different processes(two-step-method and one-step-method) of preparing LPBP were put forward, which were developed from traditional ball propellant process combining micro-capsule and macromolecule solution theories. Effects of solvent quantity, dehydrating agent strength and other technical condition on LPBP physical parameters such as shell thickness and density were studied. Photomicrography and other methods were invested to determine the shell thickness and other parameters which are relevant to the progressive burning combustion of LPBP. The combustion characteristics of LPBP with different shell thickness and different bulk density were tested by closed-vessel experiment. Results show that LPBP with different shell and core density and different shell thickness can be prepared through two-step-method or one-step-method by change the technical condition. More solvent and salt and longer time at two-step-method would lead to a thicker shell which resulting into large bulk density. The smaller the bulk density was, the faster the LPBP burned. LPBP exhibits distinct progressive burning combustion, which result from the high shell density and the low core density. The gas generating and increasing rate of LPBP can be control by adjusting the thickness ratio of the shell.