Research On The Influence Of Binder System On The Combustion Characteristics Of Gas Generating Agents

In order to study the different test phenomenon of gas generating propellant grain containing different binder systems in field of the engineering application,binders including polybutadiene(CTPB,HTPB)polyether(PET)and azido polyether(PBT,GAP)have been choosed as the research object to study the combustion characteristics of different binder systems.The effect of the binder systems on the combustion characteristics of gas generating propellant and its grain has been invested,and the effect of the curing agent in the binder system on the combustion performance of the gas generating propellant also has been researched systematically.The impact of the binder system on the combustion characteristics of gas generator was investigated.A physical combustion model for the effect of the binder system on the combustion characteristics of gas generator was constructed.The results of the article could provide theoretical guidance for the research and application of gas generator and its grain in different binder systems.The morphologic characteristics of melting film with different binder systems was investigated by the muffle furnace experiment.The results showed that in the process of heating(from 25? to 400?),the phenomenon of melting of polybutadiene(CTPB and HTPB)was not obvious.Polyether(PET)could form a well fluidity "molten liquid"(from 25? to 400?),and the azido polyether(GAP and PBT)decomposited sharply without "melting" process in the same situation.The thermal decomposition characteristics of different binder systems/AP were studied by DSC-TG ect.The results showed that when the temperature reached the low temperature of AP decomposition,CTPB and HTPB system decoposited slightly which could still guarantee the integrity of the structure and had no effect on the decomposition of AP.The structure of PET was destroyed before AP was decomposed.The formation of good fluidity oligomers could cover the surface of AP and hindered the decomposition of AP.The severe thermal decomposition reaction of GAP and PBT occurred at 250?,which produced a large amount of heat to further promote the decomposition of AP.The effect of the binder system on the combustion characteristics of gas generator has been studied by static burning rate test.The effect of the curing agent in the binder system on the combustion performance of gas generator also have been studied by static burning rate test.The surface morphology and surface element distribution of the flameout surface were observed by SEM-EDS.The results showed that the flameout surface of the "refractory" CTPB and HTPB were not smooth,and there was a lot of residual carbon residue in the surface.The burning rate of CTPB and HTPB was higher than that of PET system.When the pressure changed(from low to high),the pressure index of CTPB and HTPB increaseed greatly.Comparing with the flameout surface of CTPB and HTPB,The flameout surface of "fusible" binder PET was more smooth.When the pressure changed(from low to high),the burning rate of PET rises slightly,and the extent of rise of the burning rate pressure index is lower than that of polybutadiene.The burning rate of PBT and GAP system gas generator was higher than that of PET system.Comparing with the burning rate pressure index of the PET system,the generators of PBT and GAP system had higher burning rate pressure index in low pressure range.The type of curing agent had little effect on the combustion performance of HTPB and PET type gas generator except for DDI system.The introduction of DDI in HTPB and PET can reduce the pressure index of gas generator.Combined the combustion characteristics of gas generating propellant of different binders with the combustion characteristics of gas generating propellent grain,it could draw a conclusion that the difference of binder systems was one of the factors leading to the difference of combustion performance of grains.On account of different pressure index and cone angle effect,gas generating propellent grains of different binder systems present different combustion characteristics.