Study On Preparation Technology Of Spherical Propellant With Microporous/Hollow Core Structure

Based on the preparation of spherical propellant by the inner dissolution method,the preparation of a microporous spherical propellant with a network-like microporous structure was designed by using the water-holding and water-retaining properties of the polymer emulsifier sodium carboxymethyl cellulose craft.At the same time,combined with the double emulsification method for preparing monodisperse W/O/W double layers structure emulsion,a process for preparing hollow structure spherical medicine was invented.The controlled variable method is adopted to prepare a series of porous and hollow spherical propellants by changing one single variable.The morphology and structure of the microporous spherical propellants and hollow-core spherical propellants are observed and recorded by a three-dimensional microscope with ultra-depth of field,and the diametes of spherical propellants are counted.The particle size of the spherical propellant is measured by the bulk density method;the hygroscopicity of the microporous spherical propellant is measured by Dynamic Vapour Sorption Intrinsic.Draw the following conclusions:Microporous structure spherical propellant is spherical or nearly spherical structure,and a large number of microporous structures can be observed in the profile direction.Most of the particle size is above 1.0mm,and the bulk density is between 0.2-0.35g/cm~3.Active calcium phosphate is used in the preparation.If concentration of active calcium phosphate is greater than 0.010g/m L,a spherical propellant with a higher roundness of microporous structure can be obtained,and as the concentration of active calcium phosphate increasees,the particle size decreases;the microporous spherical propellant prepared by using nitrocellulose with higher nitrogen content.As the particle size increases,the bulk density decreases;in the stage of emulsification into balls,with the stirring speed or the concentration of emulsifier sodium carboxymethyl cellulose increases,the particle size of the microporous spherical propellant sample decreases,and the bulk density increases.The moisture absorption time of the microporous structure spherical medicine is basically balanced when it is more than 2 hours,and the moisture absorption rate is between4%-6%.The net-like microporous structure of the microporous spherical propellant has a positive effect on the hygroscopicity.But the stirring speed,concentration of emulsifier and the nitrogen content of the nitrocellulose have unconspicuous effect on the hygroscopicity of the microporous spherical propellant.The appearance of the hollow spherical propellant is similar to that of the microporous spherical propellant.A large cavity structure can be observed on the profile direction,with a particle size higher than 0.7mm and a bulk density of 0.1-0.2g/cm~3.As the stirring speed decreases,the particle size of the spherical propellant increases,and its bulk density also decreases with the particle diameter increases;the cavity structure inside the hollow structure spherical propellant is result of the combined action of active calcium phosphate and sodium carboxymethyl cellulose.The concentration and adding order of the two emulsifiers have a great influence on the structure of the hollow spherical propellant.When the concentration of active calcium phosphate increases,the inner cavity diameter of the hollow spherical medicine decreases,and when the content of sodium carboxymethyl cellulose increases,the particle size of the spherical propellant shell decreases.The ratio of addition of sodium carboxymethyl cellulose and active calcium phosphate should be 1?1.25:1,and the ratio of active calcium phosphate to nitrocellulose content should be 0.16?0.24:1.