Research Of Solid Propellant With IPN Type Lining

The interface composed of propellant/liner/thermal barrier in the solid rocket engine is called Ⅱ interface, Ⅱ interface bonding impacts the successful working of the engine. The main factors leading to the invalidation of Ⅱ interface bonding are poor lining body performance, the single chemical reaction of Ⅱ interface and the migration of small molecules at Ⅱ interface, etc. Researchers often solved these problems by increasing the solid packing and introducing the bonding agent, but it is difficult to solve Ⅱ interface bonding problem systematically. By introducing the second network system with butyl hydroxy polyurethane lining to form interpenetrating polymer network (IPN), the performance of polyurethane lining can be improved at the molecular level, and this can be seen as a means of chemical polymer physical blending technology. In this paper,we use hydroxyl-terminated polybutadiene (HTPB), isophorone diisocyanate (IPDI), methyl methacrylate (MMA), ethyl acrylate (EA), epoxy resin (EP) as raw material, and take the interpenetrating method to fabricated Polyurethane/polyacrylate (PU/P(MMA-EA)) and Polyurethane/epoxy resin (PU/EP) IPN type solid rocket motor liner.By adopting the four factors and three levels orthogonal experiment method we established the basic parameters of the interpenetrating polymer network lining. The four factors are:curing parameters, crosslinking parameters, hard segment mass fraction and the ratio of IPN Ⅰ and Ⅱ. Orthogonal experiment results show that when the curing parameter is 1.35, the crosslinking parameter is 0.25, the hard segment content is 30% and the ratio of system is 90/10 the PU/P (MMA-EA) IPN lining has good mechanical properties.The curing reaction kinetics of the forming process of IPN lining network structure was studied using differential scanning calorimetry (DSC) of, and by using Kissnger extremum and Crane method, the curing reaction kinetics parameters of the modified resin system were determined. Fourier infrared spectroscopy (FTIR) was used to study influence factors of the reaction rate constant and the curing reaction rate of IPN lining. Rheometer was used to study the influence factors of viscosity growth rate of the PU/P (MMA-EA) IPN lining. The results show that with the ratio of PU and P (MMA-EA) system become closer,the curing reaction apparent activation energy of IPN lining decrease gradually, and the reaction rate is accelerated, the reaction series is 1.065. Reaction temperature and the content of acrylate affect the consumption of -NCO greatly; Reaction temperature, curing parameters, crosslinking parameters and hard segment content have greater impact on viscosity growth rate.By adjusting the catalyst content, curing parameters, hard segment content, crosslinking parameters, initiator content and the ratio of IPN systems, a series of parameter changes on the IPN lining ontology layer and propellant/liner/thermal barrier interfacial bonding performance are studied. The results show that as the curing parameters, hard segment content, P (MMA-EA) content and EP content increased, tensile strength of IPN lining first increased and then decreased. With the increase of catalyst content and initiator content the tensile strength of IPN lining first increased then decreased, and with the increase of crosslinking parameter tensile strength of IPN lining decreased continuously. With the increase of catalyst content and crosslinking parameters, the ductility of IPN lining decreases continuously. Along with the increasing of hard segment content, the ductility of IPN lining increased, and with the increase of the initiator content, P (MMA-EA) content and EP content, the ductility of IPN first increased and then decreased, while the curing parameters impact little on the ductility of IPN lining. The effects of each parameter changes on interfacial bonding performance of propellant/liner/thermal barrier are close to mechanical performance.The positron annihilation parameters of PU/P (MMA-EA) IPN was tested by using positron annihilation lifetime spectrometer (PALS), and the average free volume radius was calculated to be-0.385 nm by using the quantum theory model. Solvent extraction method was taken to measure the gel content of different ratio system of PU/P (MMA-EA) IPN, and the crosslinking density of was calculated to be～5.41×10-6mol·cm-3。Thermal decomposition of PU/P (MMA-EA) IPN was tested by differential thermal analyzer, the result showed that the thermal decomposition of PU/P (MMA-EA) IPN included two stages, the first phase of decomposition was the hard segment and the second phase was the pyrolysis of soft long chain polymer and the decomposition of polyolefin network. The dynamic thermal and mechanical properties of the PU/P (MMA-EA) IPN were tested by DMA. The relationship of loss factor, energy storage modulus and loss modulus with temperature of different ratio system lining were also studied.