| A wealth of attention has been paid to Nitrate Ester Plasticized Polyether (NEPE) propellants, due to their high energy, good technology characteristics, good safety characteristics and long life. They are publicly reported to be the highest energy solid propellants in applications. NEPE propellants are comprised of oxidants, adhesives, plasticizer, burning agents and functional additives. The mass percents of the oxidants are around 57～71.wt % of the propellants. For the rheological properties, mechanical properties, combustion characteristics of NEPE propellants, the influence of oxidants is the largest. The propellants can easily arise "dewetting" in the process of use and the mechanical properties will become worse, because nitramine can be dissolved in nitrate ester plasticizer, and a fragile soft layer can form around the nitramine. Neutral Polymeric Bonding Agents (NPBA) have solved the "dewetting" very effectively and improved the mechanical properties. But As most of the research work focuse on solving practical engineering problems in both China and other countries. A quantitative investigation has not been reported which are about plasticizer dissolving nitramine and NPBA adsorption on the surface of RDX. The present article will discuss such problems in order to provide technical and theoretical basis for the further development of propellants.On the study of military RDX, self-made nitroglycerin(NG) and NPBA, it was studied that hygroscopicity charactericstic of RDX in different humidity environment, solubility of RDX in NG and adsorption capacity of RDX for NPBA in temperature conditions of 50℃.The results showed that RDX would not adsorb water in environment. The mass of RDX dissolved in NG increased by the increasing of time in the first 6 hours, then it increased slowlier, and got up to a balanced solution after 11 hours. The solubility of RDX in NG was 1.01 wt.%. The adsorption capacity of RDX for NPBA, Qe increased by the increaseing of Ce(percentage of quality of NPBA in NG when the adsorption keeps balance) at first, when Ce was 0.275%, a flat line showed, and it extended to 0.837%, then the adsorption capacity increased slowly by the increase of Ce. On the description of adsorption isotherm by the BET multimolecular adsorption model, correlation coefficient R was high, date correlation was good, and the BET multimolecular adsorption model was suitable for analyzing the adsorption of RDX for NPBA. The adsorption process could be considerd that NPBA molecules gradually occupied the surface of RDX by the increase of w2%(the concentration of NPBA in NG), and formed a monolayer adsorption when the value of w2% was small. After the single-strorey adsorption reached saturation, when w2% was in a certain ambit, Qe changed little. when w2% continued to increase, NPBA molecules could form hydrogen bonds, even appeared intertwist between NPBA molecules, and then the adsorption turned to multilayer adsorption. |
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