Combustion Characteristics of Polymer-coated Nitramine Composite Propellants

The promotion of the technology polymer coating nitroamine-based composite propellant burning characteristics bookmark0 and difficult to promote the use. In order to increase the specific impulse and burning rate, it is necessary to develop a propellant with a high nitramine content. The method of coating poly(vinyl acetate or ethyl cellulose) on the surface of nitramine particles was studied. The use of polymer-coated nitroamines can improve the wettability and miscibility of nitramine and hydroxyl-terminated polydiene (HTPB). While increasing the amount of nitrosamines in the propellant, metal-fuel boron is added and the nitramine/hydroxyl-terminated Polybutadiene propellants increase the burning rate and the possibility of specific impulses. The following issues were clarified: 1) The use of polymer-coated nitroamines can increase the content of nitrosamines in propellants by 2%. Following this. For comparison, uncoated ANs are also shown together in the figure. According to this figure, the shear stress of the uncoated AN and HTPB blends increases as the AN content increases, reaching a maximum at about 83 Wt% AN. When the coating AN is used, it can be roughly represented by a curve irrespective of the addition amount of the coating agent. Even with various coating agents, the shear stress reaches a maximum at an AN content of about 93 Wt%. It was proved that the AN particle surface coated with polyvinyl acetate or ethyl cellulose, the maximum shear stress AN content was added from 83Wt% to 93Wt%. AN limit content can be considered in the maximum shear stress AN content Take the 0.920.98 range. As described above, a propellant having an AN content of 86 Wt% and 91 Wt% can be produced when a polyvinyl acetate or ethyl cellulose coating AN is used.

The addition of a surfactant to the AN/HTPB mixture can increase the AN content of the mixture at its maximum shear stress. Therefore, it can be considered that the addition of a surfactant to the mixture of the coating AN and HTPB further improves the mixing of AN and HTPB and further increases the limit content of AN. Laurylamine has been reported to be most effective for improving the mixing of AN and HTPB, so laurylamine was added to the coating AN and HTPB mixture and its shear stress was measured. Their relationship between AN content and shear stress is roughly the same. This shows that the wettability of the coating AN and HTPB cannot be further improved even if the surfactant is added.

2.2 AN limit content of the coated AN propellant In the previous section, it was assumed that the AN limit of the coating AN was in the range of 86 Wt% and 91 Wt%. Propellants having an AN content of 86 Wt% or more were produced using P-0.1AN and E-0.1AN listed in Table 1, and their burning rates were measured. The results are shown. From this figure, it can be seen that as the AN content increases, the burning rate increases. When using various kinds of coating AN, the relation between pressure and burning rate can be represented by a straight line when the AN content is less than 91 Wt%, and the error of the relationship when the AN content is 92 Wt% cannot be represented by a straight line. This is because when the AN content is 92 Wt%, voids are generated in the propellant and an error occurs in the burning rate. From this, it can be judged that the propellant limit AN content using P-0.1AN or E-0.1AN was 91 Wt%. The same was done with other ANs listed in Table 1. From this figure, it can be seen that when various coating agents are used, the less the amount of coating agent added, the higher the burning rate, and the burning rate is substantially the same when the amount of the coating agent added is 0.05 g or less. If the addition amount of the coating agent is reduced, the thickness of the coating agent on the AN particle surface decreases. The relationship between the burning rate and the thickness of the coating agent at a pressure of 7 MPa is shown. When the thickness of the coating is 5.9 nm or more when the AN is coated with polyvinyl acetate, and the thickness of the coating is 6.6 nm or more when the AN is coated with ethyl cellulose, the thickness of the coating agent affects the burning rate, and the coating speed As the thickness increases, the burning rate decreases. The propellant burning rate produced in the following components is as shown. From this figure, it can be seen that the burning speed of the boron-containing propellant is higher than that of the AN content of 91 Wt%. Even if the AN content is reduced, the burning rate increases if the boron content is increased.

In the scope of this experiment, use AN/B/H! The propellant theory of PB=72.9n4.3n2.8 has a propellant specific impulse ratio of 2460Ns/kg and the propellant specific impulse of AN content 91Wt% increases 260N,/kg. Table 2 The mass content of AN/B/HTPB propellant Mass content 3 Conclusion In this experiment, the use of polyvinyl acetate or ethyl cellulose coating AN to improve the infiltration of AN and HTPB, thereby increasing its mixing, in addition to increasing the AN content in the propellant upper limit, while adding boron to explore the AN /HTPB propellant burn rate and specific impulse increase. The results are as follows: 1) The AN content of the propellant can be increased by 10Wt% using the polymer coating AN; 2) The coating agent used in this experiment will reduce the propellant burning rate and the burning rate The amount is related to the thickness of the coating agent on the surface of the AN particle; 3) In order to increase the burning rate and specific impulse, when the boron is added with the metal fuel, the propellant manufactured using the ratio of AN/B/HTPB=72.9 å…«4.3 å…« 2.8 has a burning rate of 7 MPa. The following is 5.2mm/s, the theoretical ratio is 2 Wang Yongshou