Basic Research On Thermoforming And 3D Printing Of Composite Solid Propellant

Composite solid propellant is a high-energy elastomer composite.The existing propellant binder is generally a thermosetting curing system,which has a series of shortcomings,such as: long curing cycle,non-recyclable and large amount of mixing.Moreover,with the rapid development of aerospace,designers have put forward higher and higher requirements for rocket engine charging,for example,the complexity of the combustion surface.The limitations of traditional casting process and screw pressing process for complex burning surface charging are as follows: high cost of complex mold design and development,and difficulties in demoulding after propellant curing.In view of the above problems,this thesis intends to design thermoplastic elastomer adhesives and UV curing adhesives for synthetic propellants separately.The former is suitable for rapid hot pressing of propellants,and the latter is suitable for 3D printing of propellants.The main work carried out in this thesis is as follows:In the second chapter,plasticizers were used to plasticize poly-(styrene-butadiene-styrene)(SBS)to obtain materials with desirable mechanical properties(??6.5MPa,??490%)and processing temperature(?130°C).The mathematical model of the modified SBS viscous flow temperature is obtained by MATLAB fitting,and its extended application is explored.The propellant counterfeit sample prepared by mixing with the propellant powder substitute at a mass ratio of40:60 has excellent performance(??1.3MPa,??120%).The ?65mm drug pseudo-column forming experiment was carried out by self-designed steel mold.The process temperature of hot pressing process was ?130°C,and the duration was?4.0h.After being exposed to room temperature for 90 days,the shape of the drug column was good and there was no cold flow phenomenon.In the third chapter,the polyol PBA,IPDI,BDO,HEA and other raw materials were used to synthesize UV-cured PUA.The propellant substitute slurry was prepared by mixing the PUA resin with the substitute at a mass ratio of 25:75.The effects of various factors on the properties of PUA resin and substitute slurry were explored.The results show that the viscosity of the resin obtained by the optimized formula is4200mPa·s,so it can be used for 3D printing;The cured resin film(??3.5MPa,??230%)and the solidified slurry of the substitute slurry(??0.53 MPa,??85%)have excellent mechanical properties;The curing speeds of the two were 10 s and 30 s,respectively;the shrinkage rates were 3.35% and 5.12%,respectively.The 3D printing and curing of the substitute slurry with a solid content of 75% was initially achieved.