Research On The Impact Resistance And Toughening Mechanism Of RP5 Nitroamine Gun Propellant

In order to improve the impact resistance of nitramine gun propellant, aiming to a nitramine gun propellant(RP5), samples were prepared by adding concentration range of 1%,2%,3%(w%) macromolecule toughening agent that is a glycidyl azide polymer(GAP) of low polymerization degree or a thermoplastic polyurethanes(TPU) of high polymerization degree respectively by half-solvent method. The process of drying the samples could be standardized. Axial impact strength and radial impact strength of the samples were tested by using drop impact testing machine and pendulum impact testing machine. The submicrostructure of fracture suface tested at the low-temperature was observed by a microscope. Different contents of hexogen(RDX) was added to substrate that is nitramine gun propellant(RP5) samples with the preferred amount of one toughening contents. The samples' impact strength was tested by pendulum impact system and studied toughening mechanism by percolation theory. The main results of this paper are as follows:(1) Because nitramine gun propellant should be molded by extrusion, nitrocellulose macromolecular chains will form partially oriention structure and it would make the difference between radial and axial impact resistance in the same samples.(2) For the RP5 nitroamine gun propellant, the radial and axail impact resistance of propellant samples can be improved 23.1% and 6.6% by adding preferably 1%(w%) GAP. Performance of samples will adversely affect when adding excessive amount of GAP.(3) For the RP5 nitroamine gun propellant, the radial impact resistance of propellant samples can be improved 22.8% by adding preferably 3%(w%) TPU. Samples have preferred axail impact resistance by adding 2%(w%) TPU, and it can withstand heavier hammer and faster speed impact than samples containing GAP or no toughening agent.(4) The graph of samples radial impact strength which adding the preferred amount of GAP or TPU versus the theoretical particle spacing of RDX based on percolation theory. The graph shows that the point of brittle-ductile transition is w(RDX)=32.6% or w(RDX)=33.0%.