Characterization, Prediction And Optimization Of The Interfacial Adhesion Of Composite Solid Propellant

Composite solid propellant is an energetic composite material ,which has a variety of interfaces. The surface nature of each group and the inter-group bonding situation have seriously affected the mechanical properties of the propellant, thus the study of the surface properties of the propellant components and the interfacial adhesion properties of composite solid propellant are important links for research work.The main topic of the subject is high-energy four groups(AP/RDX/Al/HTPB)hydroxyl- terminated propellant.Based on composite solid propellant's formulation composition and mixed curing technological, we analysised that the main influence factors related to the interfacial adhesion properties between the filler and polymer matrix's in propellant grain include interfacial bonding, interfacial wetting function and interfacial acid-base function. We have established the contact angle measurement and inverse gas chromatography method, at the same time we calculated out the work of interfacial adhesion and enthalpy of interfacial acid-base function among main components,and combining with the way of groups'bonding formation.Then the conditions of interfacial adhesion have been estimated in different components.Firstly, according to contact angle measurement, the contact angle of AP,RDX and AP,RDX treated with kinds of different BA,NPBA has been detected. The surface tension, polar force parameter of the surface tension, dispolar force parameter of the surface tension and polar fraction has been calculated. From the parameters, the interfacial tension, work of interfacial adhesion between fillers and hydroxyl-terminated polyurethane matrix has been calculated. The interfacial adhesion properties have been estimated by means of these parameters. The result showed that the solid filler AP and RDX treated by bonding agents such as BA-1, BA-10 and NPBA-28 have better interfacial properties.Secondly, By means of Equation of Drago.R.S,the surface acid-base property parameter of the main components which in four groups( AP/RDX/Al/HTPB)hydroxyl-terminated propellant characterized by inverse gas chromatography(IGC).Then we calculated out the enthalpy of interfacial acid-base function(â–³HAB)of the main components.The conclusion showed that the bonding agent can be preferential adsorbed on the solid filler's surface, and because of the enthalpy between the bonding agent and the AP or RDX is hingher than PU matrix and the AP or RDX, also hingher than the bonding agent and PU matrix. At last, reaction mechanism of AP, RDX with kinds of different BA, NPBA has been analyzed, which is useful to explain action of the bonding agent and affection to interfacial adhesive properties. The solubility parameter of RDX, bonding agents and matrix has been estimated. According to interfacial diffusion theory, we have predicted the interfacial compatibility between the modified filler and matrix will be better.The conclusion showed that the bonding agent can be adsorbed on the solid filler surface, and because of their high degree of functionality to create high crosslinking density of high modulus interlayer, and the transition layer and the AP, RDX higher wetting work and the enthalpy of acid-base function, but also a chemical bond with the substrate and physical entanglements crosslinking. By comprehensive consideration of interfacial wetting function, interfacial acid-base function, interfacial bonding function and interfacial compatibility in the study, we prediction that the bonding agents such as NPBA-28, BA-8 and BA-1 can improve the interfacial bonding situation and enhance mechanical properties of composite solid propellant. The formed ideas and methods can also be used for other types of propellants.